Klaviyo (KVYO) 10-K 29 Feb 24 2023 FY Annual report Financial data

Cover

Cover - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2023	Feb. 23, 2024	Dec. 29, 2023
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-41806
Entity Registrant Name	Klaviyo, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-0989964
Entity Address, Address Line One	125 Summer Street
Entity Address, Address Line Two	6th Floor
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02110
City Area Code	617
Local Phone Number	213-1788
Title of 12(b) Security	Series A common stock, par value $0.001 per share
Trading Symbol	KVYO
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 2.6
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement relating to its 2024 Annual Meeting of Stockholders are incorporated by reference in Part III of this Annual Report on Form 10-K where indicated. Such Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Amendment Flag	false
Entity Central Index Key	0001835830
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2023
Series A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		64,329,482
Series B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		196,905,047

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	Deloitte & Touche LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	34

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 738,562	$ 385,820
Restricted cash	409	409
Accounts receivable, net of allowance for doubtful accounts	23,076	10,723
Deferred contract acquisition costs, current	15,198	11,215
Prepaid expenses and other current assets	26,244	19,336
Total current assets	803,489	427,503
Property and equipment, net	43,450	45,837
Right-of-use assets, net	36,987	45,695
Deferred contract acquisition costs, non-current	23,177	15,983
Restricted cash, non-current	686	687
Prepaid marketing expense	173,844	84,415
Other non-current assets	7,417	8,959
Total assets	1,089,050	629,079
Current liabilities:
Accounts payable	13,597	8,890
Accrued expenses	62,838	36,126
Lease liabilities, current	14,081	14,864
Deferred revenue	40,100	25,109
Total current liabilities	130,616	84,989
Lease liabilities, non-current	37,498	47,544
Other non-current liabilities	6,159	876
Total liabilities	174,273	133,409
Redeemable Common Stock (Note 11)
Redeemable common stock, $0.001 par value, 0 and 64,046,223 shares issued and outstanding at December 31, 2023 and 2022, respectively.	0	1,531,853
Stockholders’ Equity (Deficit)
Preferred stock: $0.001 par value; 100,000,000 and 0 shares authorized; 0 and 0 shares issued; 0 and 0 shares outstanding at December 31, 2023 and 2022, respectively.	0	0
Additional paid-in capital	1,713,560	1,249,065
Accumulated deficit	(799,043)	(2,285,419)
Total stockholders’ equity (deficit)	914,777	(1,036,183)
Total liabilities, redeemable common stock, and stockholders’ equity (deficit)	1,089,050	629,079
Redeemable Common Stock
Redeemable Common Stock (Note 11)
Redeemable common stock, $0.001 par value, 0 and 64,046,223 shares issued and outstanding at December 31, 2023 and 2022, respectively.	0	1,531,853
Series A Common Stock
Stockholders’ Equity (Deficit)
Common stock	41	0
Series B Common Stock
Stockholders’ Equity (Deficit)
Common stock	$ 219	$ 171

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Redeemable common stock, shares outstanding (in shares)	0	64,046,223
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	100,000,000	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Redeemable Common Stock
Redeemable common stock, par value (in dollars per shares)	$ 0.001	$ 0.001
Redeemable common stock, shares issued (in shares)	0	64,046,223
Redeemable common stock, shares outstanding (in shares)	0	64,046,223
Series A Common Stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	3,000,000,000	0
Common stock, shares issued (in shares)	40,841,834	0
Common stock, outstanding (in shares)	40,841,834	0
Series B Common Stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	350,000,000	316,000,000
Common stock, shares issued (in shares)	218,524,009	170,882,108
Common stock, outstanding (in shares)	218,524,009	170,855,313

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenue	$ 698,099	$ 472,748	$ 290,640
Cost of revenue	177,888	128,025	84,696
Gross profit	520,211	344,723	205,944
Operating expenses:
Selling and marketing	394,369	213,848	156,342
Research and development	262,177	104,077	65,599
General and administrative	194,287	81,834	63,236
Total operating expenses	850,833	399,759	285,177
Operating loss	(330,622)	(55,036)	(79,233)
Other income (expense):
Other (expense) income	(470)	388	28
Interest income	24,051	5,538	139
Interest expense	0	0	(8)
Total other income	23,581	5,926	159
Loss before income taxes	(307,041)	(49,110)	(79,074)
Provision for income taxes	1,192	83	319
Net loss	(308,233)	(49,193)	(79,393)
Comprehensive loss	$ (308,233)	$ (49,193)	$ (79,393)
Net loss per share attributable to Series A and Series B common Stockholders, basic (in dollars per share)	$ (1.27)	$ (0.21)	$ (0.36)
Net loss per share attributable to Series A and Series B common Stockholders, diluted (in dollars per share)	$ (1.27)	$ (0.21)	$ (0.36)
Weighted average common shares outstanding, basic (in shares)	242,889,272	229,857,206	220,865,179
Weighted average common shares outstanding, diluted (in shares)	242,889,272	229,857,206	220,865,179

Consolidated Statements of Chan

Consolidated Statements of Changes in Redeemable Common Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series A Common Stock	Series B Common Stock	Conversion of Redeemable Common Stock	Conversion of Common Stock Upon Shareholder Election and Vesting of Certain Equity Awards	Conversion of Common Stock Upon Exercise of Greenshoe Option	Common Stock Series A Common Stock	Common Stock Series B Common Stock	Common Stock Conversion of Redeemable Common Stock Series B Common Stock	Common Stock Conversion of Common Stock Upon Shareholder Election and Vesting of Certain Equity Awards Series A Common Stock	Common Stock Conversion of Common Stock Upon Shareholder Election and Vesting of Certain Equity Awards Series B Common Stock	Common Stock Conversion of Common Stock Upon Exercise of Greenshoe Option Series A Common Stock	Common Stock Conversion of Common Stock Upon Exercise of Greenshoe Option Series B Common Stock	Additional Paid-In Capital	Additional Paid-In Capital Conversion of Redeemable Common Stock	Accumulated Deficit	Accumulated Deficit Conversion of Redeemable Common Stock
Beginning balance (in shares) at Dec. 31, 2020	61,020,598
Beginning balance at Dec. 31, 2020	$ 922,883
Redeemable Common Stock
Redeemable common stock issued (in shares)	3,025,625
Issuance of redeemable common stock, net of issuance costs of $79	$ 100,921
Accretion of redeemable common stock to redemption value	$ 1,542,528
Ending balance (in shares) at Dec. 31, 2021	64,046,223
Ending balance at Dec. 31, 2021	$ 2,566,332
Beginning balance (in shares) at Dec. 31, 2020							0	151,048,048
Beginning balance at Dec. 31, 2020	(759,737)						$ 0	$ 151						$ 0		$ (759,888)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of common stock options (in shares)								8,267,207
Issuance of common stock upon exercise of common stock options	5,853							$ 8						5,845
Accretion of redeemable common stock to redemption value	(1,542,527)													(145,582)		(1,396,945)
Issuance of common stock, net of issuance costs (in shares)								7,339,392
Issuance of common stock, net of issuance costs	244,805							$ 8						244,797
Repurchase and retirement of common stock (in shares)			(4,967,420)
Repurchase and retirement of common stock	(140,413)		$ (5)											(140,408)
Stock-based compensation expense	35,248													35,248
Vesting of restricted stock common stock (in shares)								35,727
Vesting of restricted common stock	100													100
Vesting of restricted stock units (in shares)								33,333
Vesting of restricted stock units	0
Net loss	(79,393)															(79,393)
Ending balance (in shares) at Dec. 31, 2021							0	161,756,287
Ending balance at Dec. 31, 2021	(2,236,064)						$ 0	$ 162						0		(2,236,226)
Redeemable Common Stock
Accretion of redeemable common stock to redemption value	$ 1,034,479
Ending balance (in shares) at Dec. 31, 2022	64,046,223
Ending balance at Dec. 31, 2022	$ 1,531,853
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of common stock options (in shares)								1,551,963
Issuance of common stock upon exercise of common stock options	1,634							$ 2						1,632
Accretion of redeemable common stock to redemption value	1,034,479													1,034,479
Issuance of common stock, net of issuance costs (in shares)								2,951,846
Issuance of common stock, net of issuance costs	69,120							$ 3						69,117
Issuance of investment option, net of issuance costs of $135	30,438													30,438
Vested warrants related to collaboration agreement	106,455													106,455
Issuance of common stock upon exercise of collaboration agreement warrants (in shares)								4,526,157
Issuance of common stock upon exercise of collaboration agreement warrants	45							$ 4						41
Stock-based compensation expense	6,802													6,802
Vesting of restricted stock common stock (in shares)								35,727
Vesting of restricted common stock	101													101
Vesting of restricted stock units (in shares)								33,333
Vesting of restricted stock units	0
Net loss	(49,193)															(49,193)
Ending balance (in shares) at Dec. 31, 2022		0	170,855,313				0	170,855,313
Ending balance at Dec. 31, 2022	(1,036,183)						$ 0	$ 171						1,249,065		(2,285,419)
Redeemable Common Stock
Accretion of redeemable common stock to redemption value	$ 399,685
Reclassification of redeemable common stock to Series B common stock (in shares)	(64,046,223)
Reclassification of redeemable common stock to Series B common stock	$ (1,931,538)
Ending balance (in shares) at Dec. 31, 2023	0
Ending balance at Dec. 31, 2023	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of common stock options (in shares)	2,419,308							2,419,308
Issuance of common stock upon exercise of common stock options	$ 4,144							$ 3						4,141
Accretion of redeemable common stock to redemption value	(399,685)													(399,685)
Issuance of common stock, net of issuance costs (in shares)							11,507,693
Issuance of common stock, net of issuance costs	320,096						$ 12							320,084
Issuance of common stock upon vesting of restricted stock units (in shares)							27,250	7,179,136
Issuance of common stock upon vesting of restricted stock units	0							$ 7						(7)
Vested warrants related to collaboration agreement	142,326													142,326
Issuance of common stock upon exercise of collaboration agreement warrants (in shares)								6,051,285
Issuance of common stock upon exercise of collaboration agreement warrants	62							$ 6						56
Stock-based compensation expense	342,148													342,148
Vesting of restricted stock common stock (in shares)								26,795
Vesting of restricted common stock	75													75
Shares withheld for tax withholding upon vesting of restricted stock units (in shares)		(11,874)	(2,735,286)
Shares withheld for tax withholding upon vesting of restricted stock units	(81,511)						$ (1)	$ (2)						(81,508)
Conversion of common stock (in shares)									64,046,223	27,548,447	(27,548,447)	1,770,318	(1,770,318)
Conversion of common stock				$ 1,931,538	$ 0	$ 0			$ 64	$ 28	$ (28)	$ 2	$ (2)		$ 136,865		$ 1,794,609
Net loss	(308,233)															(308,233)
Ending balance (in shares) at Dec. 31, 2023		40,841,834	218,524,009				40,841,834	218,524,009
Ending balance at Dec. 31, 2023	$ 914,777						$ 41	$ 219						$ 1,713,560		$ (799,043)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Redeemable Common Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Statement of Stockholders' Equity [Abstract]
Payments of stock issuance costs, temporary equity		$ 79
Payments of stock issuance costs	$ 307	$ 270
Payments of investment option issuance costs	$ 135

Consolidated Statements of Cash

Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (308,233)	$ (49,193)	$ (79,393)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	13,651	9,040	5,269
Non-cash operating lease costs	12,997	11,831	9,120
Amortization of deferred contract acquisition costs	15,764	10,613	3,358
Amortization of prepaid marketing expense	52,897	22,040	0
Loss on disposal of property and equipment	6	0	5
Bad debt expense	524	734	1,819
Stock-based compensation expense	340,799	6,802	35,248
Deferred income tax	(3,229)	0	0
Other	118	75	42
Changes in operating assets and liabilities:
Accounts receivable	(12,877)	(5,164)	(5,086)
Deferred contract acquisition costs	(26,941)	(20,195)	(11,277)
Prepaid expenses, prepaid taxes, and other assets	(2,375)	(5,180)	(14,124)
Accounts payable	4,505	(21,115)	23,900
Accrued expenses	26,666	15,377	13,047
Deferred revenue	14,991	10,017	6,426
Operating lease liabilities	(15,197)	(9,272)	(10,138)
Other non-current liabilities	5,305	38	(954)
Net cash provided by (used in) operating activities	119,371	(23,552)	(22,738)
Investing activities
Acquisition of property and equipment	(3,653)	(15,821)	(13,023)
Capitalization of software development costs	(5,705)	(2,424)	(987)
Purchase of indefinite-lived intangible assets	0	0	(222)
Acquisition of business	0	(500)	0
Net cash used in investing activities	(9,358)	(18,745)	(14,232)
Financing activities
Proceeds from exercise of common stock options	4,216	1,718	5,965
Cash paid for finance leases	(21)	(21)	(16)
Cash paid to repurchase shares of common stock	0	0	(140,413)
Proceeds from exercise of warrants	62	45	0
Proceeds from issuance of common stock, net of issuance costs	0	99,558	345,726
Proceeds from issuance of common stock in initial public offering, net of issuance costs	320,096	0	0
Employee taxes paid related to net share settlement of stock-based awards	(81,625)	0	0
Net cash provided by financing activities	242,728	101,300	211,262
Net increase in cash, cash equivalents, and restricted cash	352,741	59,003	174,292
Cash, cash equivalents, and restricted cash, beginning of period	386,916	327,913	153,621
Cash, cash equivalents, and restricted cash, end of period	739,657	386,916	327,913
Supplemental disclosures of cash flow information:
Cash paid for income taxes	283	204	70
Cash paid for interest	0	0	8
Cash paid for operating lease liabilities, net of tenant incentives received	15,197	9,272	10,824
Non-cash investing and financing activities
Recognition of prepaid marketing asset	142,326	106,455	0
Vesting of restricted common stock	75	101	100
Accretion of common stock subject to redemption	(399,685)	1,034,479	(1,542,527)
Unpaid purchases of property and equipment	472	44	1,985
Reclassification of redeemable common stock to Series B common stock	1,931,538	0	0
Capitalization of stock-based compensation expense related to internal-use software	$ 1,349	$ 0	$ 2

Organization and Business Descr

Organization and Business Description	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business Description	1. Organization and Business Description Klaviyo, Inc. (the “Company”) is a technology company that provides a software-as-a-service (“SaaS”) platform to enable its customers to send the right messages at the right time across email, short message service (“SMS”) and push notifications, more accurately measure and predict performance, and deploy specific actions and campaigns. Our reviews add-on allows for the collection of product reviews within our platform and our Customer Data Platform (“CDP”) offering gives user-friendly ways to track, transform, and cleanse data as well as run more advanced reporting and predictive analysis to drive revenue growth. The platform combines proprietary data and application layers into one solution with machine learning and artificial intelligence capabilities. The Company focused on marketing automation within eCommerce as its first application use case. The Company generates revenue through the sale of subscriptions to its customers for the use of its platform. Subscription plans are tiered based on the number of consumer profiles stored on the Company’s platform and the number of emails and SMS messages sent. The Company is headquartered in Boston, Massachusetts and was incorporated in the state of Delaware on September 14, 2012. The Company has three wholly-owned subsidiaries located in the United Kingdom, Australia, and the United States. Initial Public Offering On September 22, 2023, the Company completed its initial public offering of 19,200,000 shares of our Series A common stock at a price to the public of $30.00 per share. The Company sold 11,507,693 of such shares and certain existing stockholders sold an aggregate of 7,692,307 of such shares. We received net proceeds from the IPO of approximately $320.1 million, after deducting approximately $17.7 million in underwriting discounts and commissions, and $7.4 million in offering-related expenses. In connection with the IPO, all shares of the Company’s redeemable common stock automatically converted into 64,046,223 shares of Series B common stock. In connection with and immediately subsequent to the IPO, 21,233,074 shares of Series B common stock were converted to shares of Series A common stock. On October 19, 2023, the underwriters for the IPO exercised their option to purchase additional shares granted in connection with the IPO, with respect to 2,764,066 shares of Series A common stock of a possible 2,880,000 shares. The Company received no proceeds from this transaction, as the option was an option to purchase additional shares of Series A common stock from certain existing stockholders. All restricted stock units (“RSUs”) granted to employees prior to the IPO vested upon the satisfaction of both a service condition and a liquidity event condition. These RSUs with both a service condition and liquidity event condition are collectively referred to as “Double-Trigger Awards” and are described in more detail within Note 12. Stock-Based Compensation. Upon the IPO, the vesting of certain warrants issued under the Shopify Collaboration Agreement accelerated. Specifically, the vesting associated with 3,935,793 of the outstanding warrants was accelerated resulting in an increase to Prepaid Marketing Expense of $92.6 million. See Note 2. Summary of Significant Accounting Policies for additional detail on the warrants issued in connection with the Shopify Collaboration Agreement.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these consolidated financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates. The Company expects to use the extended transition period for any other new or revised accounting standards during the period in which it remains an emerging growth company. Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions are eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant items subject to such estimates and assumptions include, but are not limited to, the allowance for doubtful accounts, determination of revenue recognition under ASC 606, estimated benefit period of deferred contract acquisition costs, estimated life of prepaid marketing expense, and historical valuation of common stock and stock-based compensation, including fair value of the investment option and warrants. The Company evaluates estimates based on historical and anticipated results, trends, and various other assumptions. The Company assesses these estimates on a regular basis; however, actual results could differ from these estimates. Segment Information Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined that it operates in one operating segment and one reportable segment as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. Revenue Recognition The Company provides a SaaS solution for personalized email and SMS marketing services through a cloud-based analytics platform. The core functionalities of the software are segmentation of users’ customer lists to facilitate targeted messaging via email and SMS and the use of data science and analytics to evaluate historical sales and predict consumer activity. Revenues are derived primarily from subscription revenues, which are comprised of subscription fees from customers accessing its hosted platform services for targeted messaging. Contractual subscriptions for customers generally auto-renew on either a monthly, quarterly, or annual basis, and customers may elect not to renew by providing at least five days’ advance notice for contracts on a monthly billing cycle and thirty days’ advance notice for contracts with any other billing cycle. The customer does not have the right to take possession of the Company’s software. Subscription pricing is determined based on a customer’s profile and messaging count and monthly messaging quantities and is considered fixed, based on a tiered pricing structure. Variable consideration in the Company’s contracts is not material but represents the overage charges incurred by customers who exceed their allotments. The Company recognizes revenue under the core principle to depict the transfer of control to the Company’s customers in an amount reflecting the consideration to which the Company expects to be entitled. In order to achieve that core principle, the Company evaluates its revenue arrangements under the five-step model as follows: (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when or as the Company satisfies a performance obligation. Typically, the SaaS subscription contracts consist of a single performance obligation, and revenue is recognized over time as the performance obligation is satisfied. The performance obligation is deemed to be satisfied ratably as the customer simultaneously receives and consumes the services that the Company performs and typically have the same term. Due to the term of a majority of the Company’s contracts being less than one year, the Company has determined a significant financing component does not exist. The Company accounts for individual performance obligations separately if they have been determined to be distinct (i.e., the services are separate if identifiable from other items in the arrangement and the customer can benefit from them on their own or with other resources that are readily available to the customer). The transaction price is allocated to the distinct performance obligations on a relative stand-alone selling price basis. Stand-alone selling prices are determined based on the prices at which the Company separately sells subscriptions. Sales taxes collected from customers and remitted to government authorities are excluded from revenue. The Company incurs fees based on transaction volume and dollars processed through its credit card processor which are classified as general and administrative expense. Through the Company’s credit card processor, all receivables related to credit cards are collected within three business days. Cost of Revenue Cost of revenue consists of costs related to supporting and hosting the Company’s software platform and channel offering for paying customers. These costs primarily include cloud-based infrastructure costs, outbound communication sending costs, employee-related costs including payroll, benefits, bonuses, and stock-based compensation expense related to the customer support team, amortization of capitalized internal-use software development costs, and allocated overhead costs, including rent, facilities, depreciation, and costs related to information technology. Deferred Revenue Deferred revenue primarily consists of billings in advance of revenue recognition from subscription services and is recognized as the revenue recognition criteria is met. The Company generally bills its subscription customers monthly on the first day of the subscription term. Deferred revenue that is expected to be recognized during the succeeding 12-month period is recorded as deferred revenue. Deferred Contract Acquisition Costs Deferred contract acquisition costs are incremental costs incurred in connection with acquiring a customer contract and consists primarily of sales commissions and the associated payroll taxes. The Company expects to benefit from those costs for more than one year as the Company primarily pays sales commissions on the initial contract, and there are no commensurate commissions paid on contract renewals. Deferred contract acquisition costs are amortized on a basis consistent with the transfer of the services to which the asset relates. This results in capitalized costs being recognized on a ratable basis over the estimated period of future benefit ranging from 18 months to 60 months. The Company estimates the future period of benefit considering the size of the customer, the current contract term, the impact of estimated customer renewal terms, and the estimated life of the technology solution underlying the contracts. The Company periodically reviews the carrying amount of capitalized costs to determine whether events or changes in circumstances have occurred that could impact the period of benefit. As of December 31, 2023 and 2022, deferred contract acquisition costs expected to be recognized within one year were $15.2 million and $11.2 million, respectively, and deferred contract acquisition costs expected to be recognized beyond one year were $23.2 million and $16.0 million, respectively. Shopify Collaboration Agreement On July 28, 2022, the Company entered into a collaboration agreement with Shopify Inc. and certain of its affiliates (collectively, “Shopify”) to form a strategic relationship for the purposes of creating greater interoperability between the Klaviyo and Shopify platforms and forming a strategic product, distribution, and marketing relationship. Shopify became a related party upon execution of this agreement. The collaboration agreement has a term of 7 years and automatically renews for successive one-year periods unless the Company or Shopify provides written notice of non-renewal. In connection with the collaboration agreement, the Company entered into 3 separate agreements including a revenue sharing agreement, common stock warrant agreement, and stock purchase agreement. Under the revenue sharing agreement, the Company will make payments to Shopify in exchange for marketing services received under the collaboration agreement, which are comprised of payments for the Shopify Core Revenue Share and payments for the Shopify Plus Integration Fee. These payments are calculated as follows: • Shopify Core Revenue Share: For all revenue generated through the use of the Company’s email and SMS marketing applications by Shopify merchants designated as “Shopify Core Merchants” in respect of leads attributed to Shopify, the Company is obligated to pay Shopify a percentage of such revenues or the amounts owed to Shopify under the terms of Shopify’s standard partnership agreements applicable to all Shopify partners, which is 15% of any revenues exceeding a $1 million threshold. • Shopify Plus Integration Fee : On a monthly basis, the Company is required to pay Shopify a fee (“Shopify Plus Integration Fee” or “Integration Fee”), subject to an annual increase at Shopify’s election (up to a maximum increase of not more than a percentage calculated through a formula provided in the revenue sharing agreement), with respect to each Shopify Plus Merchant where all of the following circumstances apply: (a) the Shopify Plus Merchant was on Shopify’s Plus program at the end of the relevant month; (b) one or more of the Shopify Plus Merchant’s covered stores has the Company’s application installed at both the beginning and at the end of the relevant month; and (c) the Company’s application received a webhook request and/or made any Application Programming Interface calls against one or more of the Shopify Plus Merchant’s covered stores in the relevant month (i.e., the Company’s application is integrated with the Shopify platform and data is flowing between them). The Company determined that Shopify is a vendor and not a customer, as the collaboration agreement is a services contract under which the Company is receiving marketing services from Shopify in exchange for payments under the revenue sharing agreement. The revenue sharing agreement is a mechanism for Shopify to be compensated for the customer acquisition and marketing services Shopify is providing to the Company. Shopify is not a reseller or distributor of the Company’s Platform, nor does Shopify provide any services on the Company’s behalf. During the year ended December 31, 2023, the Company incur red $21.9 million related to fees paid under the revenue sharing agreement. During the year ended December 31, 2022, the Company incurred an aggregate of $16.2 million fees paid to Shopify pursuant to revenue sharing arrangements, inclusive of $7.7 million paid to Shopify pursuant to the terms of the Shopify revenue sharing agreement and $8.5 million paid to Shopify pursuant to the terms of our prior agreement with Shopify that was in place prior to, and replaced by, the Shopify revenue sharing agreement. As of December 31, 2023 and 2022 , the Company had $4.5 million and $2.7 million, respectively, in accrued expenses owed to Shopify for fees payable under the revenue sharing agreement. As consideration for the collaboration agreement, the Company also issued warrants that allow Shopify to purchase up to 15,743,174 shares of common stock at a price of $0.01 per share, of whic h 25% of the warrants vested on the grant date on July 28, 2022, and the remaining 75% of the warrants vest quarterly over the remaining 5 year period. The aggregate grant date fair value of the warrants was $370.3 million and will be capitalized to prepaid marketing expense as the warrants vest. The prepaid marketing ex pense asset is amortized into selling and marketing expense on a straight-line basis over the expected benefit period, which is the 7 year term of the collaboration agreement . Pursuant to the common stock warrant agreement, upon the Company’s IPO, 25% of the total number of warrants were accelerated, and the remaining unvested portion vests quarterly over the remaining term. During the years ended December 31, 2023 and 2022, the Company capitalized prepaid marketing expense of $142.3 million and $106.5 million related to the vested warrants, respectively. For the years ended December 31, 2023 and 2022 , the Company recorded marketing expense o f $52.9 million and $22.0 million, respectively, in the Consolidated Statements of Operations and Comprehensive Loss as a component of selling and marketing expense related to the amortization of the prepaid marketing expense. As of December 31, 2023 and 2022, the Company’s prepaid marketing expense is $173.8 million and $84.4 million, respectively. As of December 31, 2023 , there is $295.4 million of unrecognized marketing expense related to the warrants that will be recognized over 5.6 years. Refer to Note 11. Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) for further discussion of the warrants. On June 24, 2022, the Company entered into a stock purchase agreement with Shopify. On the closing date of July 28, 2022, Shopify purchased 2,951,846 shares of common stock for $33.88 per share. The stock purchase agreement gives Shopify the right to purchase 15,743,174 additional shares of common stock for $88.93 per share (the “Investment Option”). The common stock and Investment Option were determined to be freestanding financial instruments purchased at fair value and were accounted for separately from the collaboration agreement, revenue sharing agreement, and common stock warrant. Refer to Note 11. Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) for further discussion of the common stock purchase and Investment Option. Research and Development Costs Research and development costs are expensed as incurred, unless they qualify as capitalized internal-use software development costs. Research and development costs consist primarily of personnel-related expenses associated with the Company’s research and development staff, including salaries, benefits, bonuses, and stock-based compensation. Advertising Costs Advertising costs are expensed as incurred. During the years ended December 31, 2023, 2022 and 2021, the Company incurred advertising expenses, which are included within selling and marketing expenses on the Consolidated Statements of Operations and Comprehensive Loss, in the amount of $41.6 million, $40.3 million, and $41.9 million, respectively. Stock-Based Compensation The Company recognizes stock-based compensation on awards granted under two stock compensation plans, which are described in more detail in Note 12. Stock-Based Compensation . The Company measures stock-based compensation awards, including stock options and RSUs, based on the estimated fair value of the awards on the date of grant. Stock-based compensation expense is recorded for awards issued to employees and non-employees at fair value with a corresponding increase in additional paid-in capital. For awards with service conditions only, the Company recognizes compensation expense on a straight-line basis over the requisite service period of the award. Forfeitures are recognized when they occur. RSUs granted under the Company’s 2015 Stock Incentive Plan are subject to both service-based and performance-based vesting conditions, whereby the performance condition is satisfied upon occurrence of a liquidity event. Compensation cost related to awards with liquidity-based vesting conditions has been recognized through December 31, 2023, as the Company’s registration statement on Form S-1 filed with the SEC in connection with the IPO became effective on September 19, 2023, which satisfied the liquidity-based vesting condition of the Double-Trigger RSUs. Compensation expense for these awards with both a service and performance condition are expensed under the accelerated attribution method which includes a cumulative catch up recorded upon the IPO for services that had been completed as of the IPO. The remaining expense for these awards is recognized using the accelerated attribution method over the remaining service period. The fair value of each RSU grant is calculated based on the estimated fair value of the Company’s common stock on the date of grant, or, if modified, the date of modification. RSUs granted under the Company’s 2023 Stock Option and Incentive Plan are for shares of Series A common stock and are currently subject to service-based vesting conditions only. Compensation costs related to these awards are recognized using the straight-line method over the service period of the award. The fair value of each RSU grant is calculated based on the fair value of the Company’s Series A common stock on the date of grant, or, if modified, the date of modification. Until our IPO, given the absence of an active market for the Company’s common stock, management and the Company’s Board of Directors (the “Board”) were required to estimate the fair value of the Company’s common stock at the time of each grant of a stock-based compensation award. The Company and the Board utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants’ Technical Practice Aid, Valuation of Privately Held Company Equity Securities Issued as Compensation to estimate the fair value of its common stock. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors in determining the value of the Company’s common stock at each grant date, including the following factors: • prices paid for the Company’s capital stock, which the Company has sold to outside investors in arm’s-length transactions, considering the rights and privileges of the securities sold relative to the common stock; • prices paid for shares of its common stock sold in secondary market transactions; • valuations performed by an independent valuation specialist; • the Company’s stage of development and revenue growth; • the market performance of comparable publicly traded companies; • adjustments necessary to recognize a lack of marketability for the common stock underlying the granted options and RSUs; • the likelihood of achieving a liquidity event for the common stock underlying the stock-based awards, such as an IPO or sale of the Company, given prevailing market conditions; and • the U.S. and global economic and capital market conditions and outlook. Following the Company’s IPO, there is an active market for its Series A common stock which is utilized to measure the fair value of the Company’s underlying shares. Redeemable Common Stock Redeemable common stock represents shares of the Company’s common stock that are redeemable at the option of the investor after a specified date. The initial carrying amount of redeemable common stock is equal to the respective issuance date fair value of the common stock subject to redemption, less issuance costs. The carrying amount is adjusted to equal the redemption value, which is equal to the fair value of a single share of common stock at the end of each reporting period. The carrying amount is subject to a floor equal to the initial carrying amount. The resulting changes in the redemption value are recorded with corresponding adjustments against retained earnings, if available, additional paid-in capital or accumulated deficit. Redeemable common stock is classified outside of permanent equity on the Consolidated Balance Sheets as the redemption option is outside of the Company’s control. As the redemption feature applicable to certain shares of the Company’s common stock was terminated upon the IPO, all shares of the Company’s redeemable common stock converted into 64,046,223 shares of Series B common stock upon the effectiveness of the Company’s registration statement on Form S-1 filed with the SEC on September 19, 2023. Refer to Note 11. Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) for further discussion. Non-Vested Restricted Common Stock The Company may grant non-vested restricted common stock to employees, directors, and consultants with or without cash consideration. These grants contain certain restrictions on the sale of the shares. Non-vested restricted common stock are considered issued, but not outstanding, for accounting purposes until they vest. Upon termination of the relationship with a holder of the non-vested restricted common stock, the Company has the right to repurchase the non-vested restricted common stock at the price paid by the holder or, if there was no consideration, a price per share as defined in the Company’s agreement with the holder of the restricted common stock. All restricted common stock was vested as of December 31, 2023. Income Taxes The Company accounts for income taxes in accordance with ASC 740, Income Taxes (“ASC 740”), which utilizes the asset and liability method for the financial accounting and reporting of income taxes. Under this method, deferred income taxes are recognized for the expected future tax consequences of differences between the tax bases of assets and liabilities and their reported amounts in the financial statements. The amount of any future tax benefit associated with deferred tax assets is reduced by a valuation allowance when there is uncertainty that those tax benefits will be realized. The Company accounts for uncertain tax positions using a more-likely-than-not recognition threshold in accordance with ASC 740. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity, and changes in facts or circumstances related to a tax position. Interest and penalties related to uncertain tax positions are included as a component of income tax expense. As of December 31, 2023 and 2022, the Company has no recorded liabilities for uncertain tax positions and has no accrued interest or penalties related to uncertain tax positions. Accounts Receivable Accounts receivable are shown net of an allowance for doubtful accounts of $1.5 million and $2.3 million as of December 31, 2023 and 2022, respectively. The allowance for doubtful accounts is established to represent the Company’s best estimate of the net realizable value of the outstanding amount of receivables that it will be unable to collect. The development of the Company’s allowance for doubtful accounts is based on a review of factors such as the customer’s payment history, historical loss patterns, the general economic climate, age, and past due status of invoices. If circumstances relating to specific customers change or unanticipated changes occur in the general business environment, the Company’s estimates of the recoverability of receivables could be further adjusted. The allowance for doubtful accounts consists of the following activity (in thousands): Year Ended December 31, 2023 2022 2021 Balance at beginning of the period $ 2,253 $ 1,917 $ 125 Provisions for uncollectible accounts, net of recoveries 28 1,224 1,792 Write offs (802) (888) — Balance at end of the period $ 1,479 $ 2,253 $ 1,917 Accounts receivable is shown inclusive of unbilled accounts receivable of $1.8 million and $0.5 million as of December 31, 2023 and 2022, respectively. The unbilled accounts receivable is made up entirely of overages incurred by customers who have exceeded their subscription allotment as of period end but are not yet due for their period end billing. Cash, Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with a remaining maturity of three months or less when purchased to be cash equivalents. As of December 31, 2023, the Company had cash equivalents of $314.5 million in money market funds. As of December 31, 2022, the Company did not have cash equivalents. As of December 31, 2023 and 2022, the Company had a current restricted cash balance of $0.4 million and $0.4 million, respectively. As of December 31, 2023 and 2022, the Company had a non-current restricted cash balance of $0.7 million and $0.7 million, respectively. Restricted cash at December 31, 2023 and 2022 related to the Company’s required collateral to fund payroll and credit card obligations in its Australian entity as well as collateral required to be held as a result of the Company’s office lease in Australia. Restricted cash is included in current assets for obligations that expire within one year and is included in non-current assets for assets that expire more than one year from the balance sheet date. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported in the Consolidated Balance Sheets to the total of the amounts reported in the Consolidated Statements of Cash Flow (in thousands): As of, December 31, 2023 December 31, 2022 Cash and cash equivalents $ 738,562 $ 385,820 Restricted cash - current 409 409 Restricted cash - non-current 686 687 Total cash, cash equivalents, and restricted cash $ 739,657 $ 386,916 Concentrations of Credit Risk, Significant Customers, and Vendors Financial instruments that potentially expose the Company to concentration of credit risk consist primarily of cash, restricted cash, and accounts receivable. The Company maintains its cash and restricted cash at accredited financial institutions. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000. As of December 31, 2023 and 2022, the Company’s primary operating accounts significantly exceeded federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Credit risk with respect to accounts receivable is dispersed due to the Company’s large number of customers. The Company routinely assesses the creditworthiness of its customers. The Company does not require collateral. The Company maintains an allowance for potentially uncollectible accounts receivable. Accounts receivable is stated at the amount management expects to collect from outstanding balances. Due to these factors, no additional credit risk beyond amounts provided for collection losses is believed by management to be probable in the Company’s accounts receivable. Significant concentrations of credit risk constitute customers that represent 10% or more of accounts receivable. As of December 31, 2023 and 2022, no individual customer accounted for more than 10% of accounts receivable. Additionally, there were no customers that represented 10% or more of the Company’s revenue for the fiscal years ended December 31, 2023, 2022, and 2021. The Company had certain vendors who individually represented 10% or more of the Company’s total vendor expenditures. For the year ended December 31, 2023, three vendors represented 19%, 14%, and 12% of total vendor expenditures, respectively. For the year ended December 31, 2022, two vendors represented 19% and 13% of total vendor expenditures, respectively. For the year ended December 31, 2021, one vendor represented 25% of total vendor expenditures, and no other vendors represented 10% or more of total expenditures for the year. Property and Equipment Property and equipment are recorded at cost and depreciated over the estimated useful lives of the related assets using the straight-line method. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation, are removed from the accounts, and any resulting gain or loss is included in the determination of net income or loss in the period of retirement. Expenditures for maintenance and repairs are charged to expense as incurred, whereas major improvements are capitalized as additions to property and equipment. The estimated useful lives of the Company’s property and equipment are as follows: Office equipment 5 years Computer equipment 3 years Furniture and fixtures 5 years Leasehold improvements Lesser of lease term or useful life Asset retirement cost Lesser of lease term or 5 years Asset Retirement Obligations (“ARO”) As part of the build out of the Company’s headquarters in Boston, Massachusetts, the Company built an internal staircase connecting multiple floors. This staircase required the removal of ground space to connect the floors. The lease agreement requires the Company to incur the costs required to restore the leased space to its original condition. During fiscal year 2020, on the lease commencement date, the Company established an ARO based on the present value of contractually required estimated future costs to retire long-lived assets at the termination or expiration of a lease and to return the space to its original condition. The asset associated with the ARO is amortized over the lease term or 5 years to operating expense, and the ARO is accreted to the end of lease obligation value over the same term. The ARO established by the Company is described in more detail in Note 5. Property and Equipment, Net. Capitalized Internal-Use Software The Company capitalizes qualifying costs incurred during the application development stage in connection with the development of internal-use software, which are included on the Consolidated Balance Sheets as a component of property and equipment, net. Costs related to preliminary project activities and post-implementation stages of software development are expensed as incurred. Costs capitalized as internal-use software development costs include eligible salaries, stock-based compensation, and other compensation-related costs of employees and costs incurred in developing new features and enhancements when the costs will result in additional functionality. Capitalized internal-use software development costs are amortized on a straight-line basis over their estimated useful life of 3 years. Computer software development costs that do not qualify for capitalization are expensed as incurred. Capitalization begins when the preliminary project stage is complete, management authorizes and commits to the funding of the software project with appropriate authority, it is probable the project will be completed, the software will be used to perform the functions intended, and certain functional and quality standards have been met. Leases The Company determines whether an arrangement contains a lease at inception. At the commencement date, the Company will perform the classification tests to de

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue Recognition	3. Revenue Recognition Disaggregation of Revenue Revenue by geographic area, based on the location of the Company’s customers, was as follows (in thousands): Year Ended December 31, 2023 2022 2021 Americas: United States $ 443,471 $ 307,222 $ 197,263 Other Americas (1) 38,180 26,790 15,758 APAC (1)(2) 72,797 47,905 27,574 EMEA (1)(3) 143,651 90,831 50,045 Total Revenue $ 698,099 $ 472,748 $ 290,640 (1) Other than the United States, no other individual country accounted for 10% or more of total revenue for any of the periods presented. (2) Asia-Pacific (3) Europe, the Middle East and Africa Deferred Revenue The change in deferred revenue reflects billings during the period for which the performance obligation was not satisfied prior to the end of the period, partially offset by revenues recognized during the period. The following table summarizes the changes in the balance of deferred revenue during the periods presented (in thousands): Year Ended December 31, 2023 2022 Balance at beginning of the period $ 25,109 $ 15,092 Plus: Billings during the period 713,090 482,765 Less: Revenue recognized during the period (698,099) (472,748) Balance at end of the period $ 40,100 $ 25,109 For the years ended December 31, 2023 and 2022, revenue recognized from amounts included in deferred revenue at the beginning of the period was $25.1 million and $15.1 million, respectively. Remaining Performance Obligations Remaining performance obligations represents the amount of contracted future revenue that has not yet been recognized, including deferred revenue. As of December 31, 2023, the Company’s remaining performance obligations are $83.3 million, of which $79.4 million is expected to be recognized within the next twelve months and $3.9 million is expected to be recognized during a period greater than twelve months.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis at the periods indicated below, by level within the fair value hierarchy (in thousands): As of December 31, 2023 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 314,511 $ — $ — $ 314,511 Total $ 314,511 $ — $ — $ 314,511 As of December 31, 2023, certain of the Company’s cash equivalents were held in money market funds. The Company’s investments in money market funds are classified within Level 1 of the fair value hierarchy as they are valued using quoted market prices in active markets. As of December 31, 2022, the Company did not have assets or liabilities carried at fair value.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment consist of the following (in thousands): As of, December 31, 2023 December 31, 2022 Capitalized internal-use software $ 11,682 $ 4,460 Office equipment 3,633 3,203 Computer equipment 2,939 639 Furniture and fixtures 7,242 6,683 Leasehold improvements 45,768 45,228 Construction-in-progress 78 82 Asset retirement cost 643 643 Total property and equipment 71,985 60,938 Less accumulated depreciation and amortization (28,535) (15,101) Total property and equipment, net $ 43,450 $ 45,837 In the years ended December 31, 2023, 2022 , and 2021 , d epreciation and amortization expense related to property and equipment was approximately $13.7 million, $8.9 million, and $5.3 million, respectively. During the years ended December 31, 2023 and 2022, the Company capitalized $7.0 million and $2.4 million of internal-use software development costs, respectively. Of the $7.0 million internal-use software development costs capitalized during the year ended December 31, 2023, $1.3 million is attributable to stock-based compensation expense. During the year ended December 31, 2022, the Company did not capitalize any stock-based compensation expense related to services performed on capitalized software development projects. The Company recorded amortization expense associated with its capitalized internal-use software development costs of $1.8 million, $0.7 million, and $0.4 million for the years ended December 31, 2023, 2022, and 2021. Amortization expense is included in cost of revenue in the Consolidated Statements of Operations and Comprehensive Loss. The asset retirement obligation is included in other non-current liabilities on the Consolidated Balance Sheets. Asset retirement obligation activity is as follows (in thousands): Year Ended December 31, 2023 2022 Beginning balance $ 722 $ 685 Additions — — Accretion 39 37 Ending balance $ 761 $ 722

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued Expenses	6. Accrued Expenses The following table presents components of accrued expenses (in thousands): As of, December 31, 2023 December 31, 2022 Accrued compensation and employee related costs $ 25,644 $ 16,926 Accrued sabbatical 3,394 — Accrued value added tax 7,530 4,937 Other accrued taxes 6,830 1,754 Accrued cost of revenue 6,656 7,923 Accrued professional services 3,605 2,297 Accrued marketing 6,374 980 Other accrued expenses 2,805 1,309 Total accrued expenses $ 62,838 $ 36,126

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Contractual Obligations and Commitments The Company has material long-term non-cancellable contractual obligations outstanding with marketing vendors and various service providers. Future minimum payments under the Company’s non-cancellable purchase commitments as of December 31, 2023, are presented in the table below (in thousands): Year Ending December 31, Contractual Commitments 2024 $ 117,668 2025 116,965 2026 70,761 2027 40,833 2028 — Total Contractual Commitments: $ 346,227 Legal Matters From time to time, the Company may become involved in legal proceedings or be subject to claims arising in the course of its business, including but not limited to claims brought by its customers in connection with commercial disputes and litigation arising from employee and ex-employee related matters. The Company is not presently subject to any pending or threatened litigation, individually or taken together, for which it is reasonably possible to have a material effect on its consolidated financial position or results of operations. Guarantees and Indemnification Obligations In the ordinary course of business, the Company enters into agreements with its customers that include commercial provisions with respect to licensing, infringement, indemnification, and other common provisions. The Company does not, in the ordinary course of business, agree to indemnification obligations for the Company under its contracts with customers except for intellectual property infringement claims related to the Company’s services. Based on historical experience and information known at December 31, 2023 and 2022, the Company has not incurred any costs for guarantees or indemnities.

Leases

Leases	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Leases	8. Leases The components of lease expense are as follows (in thousands): Year Ended December 31, 2023 2022 2021 Operating lease cost $ 12,618 $ 12,091 $ 10,517 Short-term lease cost 630 121 — Financing lease cost 21 21 16 Total lease cost $ 13,269 $ 12,233 $ 10,533 Supplemental balance sheet information related to the Company’s operating leases is as follows (in thousands): As of, December 31, 2023 December 31, 2022 Operating lease ROU assets $ 36,987 $ 45,695 Operating lease liabilities, current 14,081 14,864 Operating lease liabilities, non-current 37,498 47,544 Total lease liabilities $ 51,579 $ 62,408 Supplemental cash flow information and non-cash activity related to the Company’s leases are as follows (in thousands): Year Ended December 31, 2023 2022 2021 Cash paid for operating lease liabilities, net of tenant incentives received $ 15,197 $ 9,272 $ 10,824 ROU assets recognized for new leases and amendments (non-cash) $ 1,299 $ 3,452 $ 6,132 Other information related to leases is as follows: As of, December 31, 2023 December 31, 2022 Weighted average remaining lease term 4.1 years 5.0 years Weighted average discount rate 4.97 % 4.96 % Future undiscounted annual cash flows for the Company’s operating leases as of December 31, 2023 are as follows (in thousands): Year Ending December 31, Operating Leases 2024 $ 14,383 2025 13,237 2026 13,429 2027 12,692 2028 3,205 Thereafter — Total future undiscounted lease payments 56,946 Less imputed interest (5,367) Total lease liabilities $ 51,579 The table above does not include options to extend lease terms that are not reasonably certain of being exercised or leases signed but not yet commenced as of December 31, 2023.
Leases	8. Leases The components of lease expense are as follows (in thousands): Year Ended December 31, 2023 2022 2021 Operating lease cost $ 12,618 $ 12,091 $ 10,517 Short-term lease cost 630 121 — Financing lease cost 21 21 16 Total lease cost $ 13,269 $ 12,233 $ 10,533 Supplemental balance sheet information related to the Company’s operating leases is as follows (in thousands): As of, December 31, 2023 December 31, 2022 Operating lease ROU assets $ 36,987 $ 45,695 Operating lease liabilities, current 14,081 14,864 Operating lease liabilities, non-current 37,498 47,544 Total lease liabilities $ 51,579 $ 62,408 Supplemental cash flow information and non-cash activity related to the Company’s leases are as follows (in thousands): Year Ended December 31, 2023 2022 2021 Cash paid for operating lease liabilities, net of tenant incentives received $ 15,197 $ 9,272 $ 10,824 ROU assets recognized for new leases and amendments (non-cash) $ 1,299 $ 3,452 $ 6,132 Other information related to leases is as follows: As of, December 31, 2023 December 31, 2022 Weighted average remaining lease term 4.1 years 5.0 years Weighted average discount rate 4.97 % 4.96 % Future undiscounted annual cash flows for the Company’s operating leases as of December 31, 2023 are as follows (in thousands): Year Ending December 31, Operating Leases 2024 $ 14,383 2025 13,237 2026 13,429 2027 12,692 2028 3,205 Thereafter — Total future undiscounted lease payments 56,946 Less imputed interest (5,367) Total lease liabilities $ 51,579 The table above does not include options to extend lease terms that are not reasonably certain of being exercised or leases signed but not yet commenced as of December 31, 2023.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes The domestic and foreign components of loss before income taxes are as follows (in thousands): Year Ended December 31, 2023 2022 2021 United States $ (312,759) $ (51,729) $ (80,260) Foreign 5,718 2,619 1,186 Loss before income taxes $ (307,041) $ (49,110) $ (79,074) The provision (benefit) for income taxes contained the following components (in thousands): Year Ended December 31, 2023 2022 2021 Current: Federal $ — $ — $ — State (26) 99 45 Foreign 4,652 56 179 4,626 155 224 Deferred: Federal — (95) — State — (16) — Foreign (3,434) 39 95 (3,434) (72) 95 Provision for income taxes $ 1,192 $ 83 $ 319 The Company’s effective tax rates for the years ended December 31, 2023, 2022, and 2021 are less than the U.S. federal statutory income tax rate of 21.0% primarily due to the valuation allowance on the U.S. federal and state deferred tax assets and excess tax deductions related to stock-based compensation awards. Year Ended December 31, 2023 2022 2021 U.S. federal taxes at statutory rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 4.3 4.4 4.8 Federal research and development credits 3.8 10.3 7.9 State research and development credits 0.9 7.8 3.2 Permanent items (0.4) (1.0) (0.2) Stock-based compensation 1.6 5.6 5.0 Foreign rate differential — — — Non-deductible officers compensation (2.3) — — Prepaid marketing expense 3.6 — — Other — (0.8) 0.1 Change in valuation allowance (32.9) (47.5) (42.2) Total (0.4) % (0.2) % (0.4) % Deferred income taxes reflect the impact of carryforwards and temporary differences between the amounts of assets and liabilities for financial reporting purposes and such amounts as measured by tax laws. The carryforwards and temporary differences that give rise to a significant portion of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022, are as follows (in thousands): Year Ended December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 88,200 $ 49,093 Research and development credits 36,217 21,829 Stock-based compensation 32,204 1,218 Lease liability 12,933 17,225 Capitalized research and development 63,701 21,728 Other 5,553 2,864 Total deferred tax assets 238,808 113,957 Deferred tax liabilities: Depreciation (3,543) (5,481) Deferred commissions (7,657) (5,451) Amortization (2,049) (85) ROU asset (9,303) (13,202) Prepaid marketing expense (43,084) (20,666) Total deferred tax liabilities (65,636) (44,885) Valuation allowance (170,076) (69,205) Net deferred tax assets (liabilities) $ 3,096 $ (133) As of December 31, 2023 and 2022, the Company has federal net operating loss (“NOL”) carryforwards of $349.2 million and $199.2 million, respectively, which can be carried forward indefinitely, and state net operating loss carryforwards of $245.1 million and $118.6 million, respectively, which expire at various dates beginning in 2027. As of December 31, 2023 and 2022, the Company has federal credit carryforwards of $25.1 million and $13.6 million, respectively, and state credit carryforwards of $14.0 million and $10.4 million, respectively, which are available to reduce future tax liabilities. If not utilized, the federal research and development credit will begin to expire in 2037 and the state research and development credit will begin to expire in 2025. The Company is not subject to an annual limitation of its NOL and research and development credit attributes as of December 31, 2023, but subsequent ownership changes may affect the limitation in future years. The net changes in the total valuation allowance for the year ended December 31, 2023, was an increase of $100.9 million, primarily as a result of the generation of additional net operating losses and federal research and development credits. The net changes in the total valuation allowance for the year ended December 31, 2022 was an increase of $23.3 million, primarily as a result of the generation of additional net operating losses and federal research and development credits. The Company has not recognized any liabilities for uncertain tax positions or unrecognized benefits as of December 31, 2023 and 2022. The Company does not expect any material change in uncertain tax benefits within the next 12 months. As of December 31, 2023 and 2022, the Company had an immaterial amount of earnings from its wholly-owned non-U.S. subsidiaries indefinitely reinvested outside the U.S. The Company does not intend to repatriate these earnings or realize the outside basis differences in its foreign subsidiaries, and accordingly, the Company has not provided any taxes for those amounts, given the indefinite reinvestment and it is not practicable to estimate the amount of deferred tax liability that would be incurred.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans The Company maintains a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. The plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pretax basis, subject to legal limitations. Employees can designate the investment of their 401(k) accounts into several mutual funds. The Company does not allow investment in its common stock through the 401(k) plan. During the years ended December 31, 2023, 2022, and 2021 , the Company made contributions to the plan of $7.4 million, $6.6 million, and $3.8 million respectively. The Company contributes to defined contribution savings plans for its employees in the United Kingdom and Australia who satisfy certain eligibility requirements. The plans allow each participant from the United Kingdom and Australia to defer a percentage of their compensation and the Company contributes an additional 5% and 11% of all wages for those employees in the scheme on a monthly basis, respectively. The Company made contributions to the plans of $1.8 million, $0.8 million, and $0.3 million for the years ended December 31, 2023, 2022, and 2021 respectively.

Redeemable Common Stock, Common

Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit)	Redeemable Common Stock, Common Stock, and Stockholders’ Equity (Deficit) Redeemable Common Stock The Company issued 64,046,223 shares of common stock at various dates in 2019, 2020, and 2021 to select investors that were subject to redemption at fair value of common stock at the investor’s option after November 6, 2029. In accordance with the SEC and its staff’s guidance on redeemable equity instruments, which has been codified in ASC 480-10-S99, redemption provisions not solely within control of the Company require classification of the associated instrument outside of permanent equity. During the year ended December 31, 2021, the Company entered into the 2021 Stock Purchase agreement. The Company issued and sold 10,365,017 shares of common stock to investors at a price of $33.38 per share, for an aggregate purchase price and gross proceeds of $346.0 million. At the time of the sale, 3,025,625 of the total shares issued allowed investors to acquire additional substantive rights including financial information rights, restrictive covenants, secondary refusal rights, right of co-sale, and right of redemption after November 6, 2029, at fair value. These shares were classified outside of permanent equity. The remaining 7,339,392 shares were classified in permanent equity as they did not contain the right of redemption after November 6, 2029. As of December 31, 2022 and 2021, the Company determined that the redeemable shares were probable of becoming redeemable. In accordance with ASC 480-10-S99, the Company elected to recognize changes in redemption value immediately as they occur. The per-share redemption value is equal to the fair market value of a single share of the Company’s common stock subject to a floor of the initial carrying value. Immediately prior to the IPO, the redeemable common stock was accreted to the IPO issuance price of $30.00 per share. Upon the IPO, the redemption right of these shares was terminated and all shares of the Company’s redeemable common stock automatically converted into 64,046,223 shares of Series B common stock. This transaction resulted in a reclassification of $1,931.5 million in redeemable common stock to stockholder’s equity including an increase to additional paid-in capital of $136.9 million and Accumulated Deficit of $1,794.6 million to reverse accretion recorded to these accounts. Common Stock Immediately following the effectiveness of the registration statement relating to our IPO, we filed our Amended and Restated Certificate of Incorporation, which authorized a total of 3,000,000,000 shares of Series A common stock, 350,000,000 shares of Series B common stock, and 100,000,000 shares of undesignated preferred stock. All shares of common stock then outstanding were reclassified as Series B common stock. The rights of the holders of Series A common stock and Series B common stock are identical, except with respect to voting and conversion. Each share of Series A common stock is entitled to one vote per share and is not convertible into any other shares of the Company’s capital stock. Each share of Series B common stock is entitled to ten votes per share and is convertible into one share of Series A common stock at any time. Shares of the Company’s Series B common stock will also automatically convert into shares of Series A common stock upon certain transfers and other events. Upon the seventh Preferred Stock The Company has authorized 100,000,000 shares of preferred stock with a par value of $0.001 per share. As of December 31, 2023, there were no shares of preferred stock issued or outstanding. Common Stock Warrants On July 28, 2022, the Company granted warrants to purchase up to 15,743,174 shares of common stock in connection with the collaboration agreement and strategic partnership with Shopify as compensation for marketing services. 25% of the shares subject to the warrants vested on the grant date, and the remaining 75% of the shares subject to the warrants vest quarterly in equal amounts until July 28, 2027. On September 22, 2023, upon the Company’s IPO, the vesting of 25% of the total number of warrants was accelerated, and the remaining unvested portion vests quarterly over the remaining term. Vesting will cease, and any unvested portion of the warrants will be cancelled, in the event of a material breach or early termination of the collaboration agreement by Shopify. The exercise price is $0.01 per share, and the term of the warrants is 10 years. These common stock warrants are included as a component of additional paid-in capital within the Consolidated Balance Sheets upon vesting. The Company valued the warrants at the grant date using the Black-Scholes option pricing model with the following assumptions: fair value of common stock, a dividend yield of zero, contractual terms of 10 years, volatility of 55.00%, and a risk-free rate of 2.85%. The following table summarizes the warrants activity during the year ended December 31, 2023: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Life (years) Warrants outstanding at December 31, 2022 11,217,017 $ 0.01 9.57 Granted — — — Exercised (6,051,285) 0.01 8.95 Cancelled — — — Warrants outstanding at December 31, 2023 5,165,732 $ 0.01 8.58 During the years ended December 31, 2023 and 2022, 6,051,285 and 4,526,161 warrants vested, respectively. The Company has no vested but not exercised warrants outstanding as of December 31, 2023. Restricted Stock In 2019, the Company permitted the purchase of 142,908 shares of restricted stock prior to vesting by an employee of the Company. These shares are restricted and subject to repurchase by the Company until the conditions for vesting are met. Upon termination of employment of the restricted stockholder, the Company has the right to repurchase, at the original purchase price, any unvested restricted shares. Accordingly, the Company has recorded the proceeds from the issuance of restricted stock as a liability on the Consolidated Balance Sheets as a component of other current liabilities, given the implicit repurchase feature. As of December 31, 2022, the Company has recognized a restricted stock liability of approximately $0.1 million as a component of accrued expenses. The Company reclassified an immaterial amount of restricted stock liability to stockholders’ deficit upon vesting of restricted shares during the years ended December 31, 2023 and 2022, respectively. As of December 31, 2023, all restricted stock has been fully vested. The following is a summary of the non-vested restricted common stock activity during the year ended December 31, 2023: Number of Shares Weighted Average Grant Date Unvested and outstanding at December 31, 2022 26,795 $ 2.84 Granted — — Vested (26,795) $ 2.84 Unvested and outstanding at December 31, 2023 — $ — The aggregate fair value of restricted stock that vested was $0.7 million and $1.2 million during the years ended December 31, 2023 and 2022, respectively. Stock Purchase and Investment Option On July 28, 2022, the Company entered into a stock purchase agreement in connection with the collaboration agreement and strategic partnership with Shopify. Under the stock purchase agreement, the Company issued and sold 2,951,846 shares of common stock to Shopify at a price of $33.88 per share. The stock purchase agreement also granted Shopify an Investment Option, which allows Shopify to purchase an additional 15,743,174 shares of common stock at a purchase price of $88.93 per share. The Investment Option is exercisable at any time at Shopify’s option until July 28, 2030. As of December 31, 2023, the Investment Option has not been exercised. The Company determined that the $100.0 million purchase price represents the fair value of the common stock and Investment Option issued to Shopify since the transaction occurred at arm’s length and was not compensatory. The gross proceeds of $100.0 million were allocated to the common stock and Investment Option based on the relative fair value of each instrument, resulting in $69.4 million being allocated to the common stock and $30.6 million allocated to the Investment Option. The Company incurred $0.4 million of issuance costs which were allocated to the common stock and Investment Option based on their relative fair values. The proceeds allocated to the Investment Option, net of issuance costs, are included as a component of additional paid-in capital within the Consolidated Balance Sheets.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation Equity Incentive Plans On September 1, 2015, the Board adopted the 2015 Stock Incentive Plan (the “2015 Plan”). The Board or, at its sole discretion, a committee of the Board, is responsible for the administration of the 2015 Plan. All equity grants subsequent to the IPO will be made pursuant to the Company’s 2023 Stock Option and Incentive Plan (the “2023 Plan”), which was approved by the Board effective as of September 19, 2023. Subsequent to the IPO, generally 2015 Plan awards vest into shares of Series B common stock and are immediately reclassified to Series A common stock based upon the employee’s conversion election made at the time of the IPO. The Board or, at its sole discretion, a committee of the Board, is responsible for the administration of the 2023 Plan. As of December 31, 2023, the Company’s authorized common stock includes 44,981,488 shares of Series A common stock reserved for issuance of equity awards under the 2023 Plan, of which 40,775,315 shares are available for future grants. The 2015 Plan provides for the grant of various types of stock-based compensation awards including, but not limited to, RSUs, incentive stock options (“ISOs”), non-qualified stock options (“NSOs,” referred to collectively with ISOs as options) and restricted stock awards (“RSAs”) to directors, consultants, employees, and officers of the Company. ISOs may only be granted to employees, and the exercise price thereon cannot be less than the fair value of the Company’s common stock on the date of grant or less than 110% of the fair value in the case of employees holding 10% or more of the voting stock of the Company. The exercise price on NSOs must be at least equal to the fair value of the Company’s common stock on the date of grant. The Company has historically granted RSUs, ISOs, NSOs, and RSAs. The 2023 Plan provides for the grants of various types of stock-based compensation awards including, but not limited to, RSUs, ISOs, NSOs, and RSAs. During the years ended December 31, 2023, 2022 and 2021, the Company solely granted RSUs as further described below. Stock Options Stock Options (“Options”) generally vest over 4 years with the first 25% of the award vesting upon the 12-month anniversary of the vesting commencement date and the remaining 75% vesting monthly over the following 3 years. Grants of Options shall not be exercisable after expiration of 10 years from the date of grant or such shorter period specified in the associated award agreement. Options may not be transferable except by will or by the laws of descent and distribution and domestic relations orders. The 2015 Plan does not allow for the early exercise of Options. The Company did not grant any Options during the years ended December 31, 2023, 2022 and 2021. Option activity for the year ended December 31, 2023 is as follows (in thousands, except per share data): Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding at January 1, 2023 34,207,554 $ 0.61 3.74 $ 781,247 Exercised (2,419,308) 1.56 Forfeited and expired (53,521) 3.22 Outstanding at December 31, 2023 31,734,725 $ 0.54 2.65 $ 864,605 Exercisable at December 31, 2023 31,639,454 0.53 2.64 $ 862,297 Expected to vest at December 31, 2023 31,734,725 0.54 2.65 $ 864,605 The total intrinsic value of Options exercised during the years ended December 31, 2023, 2022 and 2021 amounted to $54.7 million, $53.2 million and $169.7 million, respectively. Restricted Stock Units During the years ended December 31, 2023, 2022 and 2021, the Company granted RSUs to employees under the 2015 Plan and 2023 Plan. In general, RSUs granted under the 2015 Plan vest upon the satisfaction of both a service condition and a liquidity condition (“Double-Trigger”). Generally, the service condition requires the grantee to remain an eligible participant, as that term is defined in the 2015 Plan, for a period of 4 years. Generally, RSUs vest quarterly over the entire 4-year period or vest 25% after 1 year, with the remainder vesting quarterly over the following 3 years. The liquidity condition was satisfied upon the occurrence of the IPO. In general, RSUs granted after the IPO under the 2023 Plan vest upon the satisfaction of a service condition only. These service conditions are consistent with those under the 2015 Plan detailed above. Restricted stock unit activity for the year ended December 31, 2023 is as follows (in thousands, except per share data): Number of Units Weighted Average Grant Date Unvested and outstanding at January 1, 2023 11,712,446 $ 30.24 Granted 11,896,929 26.23 Vested (7,206,386) 29.49 Forfeited (1,712,572) 29.51 Unvested and outstanding at December 31, 2023 14,690,417 $ 27.44 The fair value of the RSUs that vested during the years ended December 31, 2023, 2022 and 2021 was $214.7 million, $1.3 million and $0.5 million, respectively. Modifications During the year ended December 31, 2023, the Company extended the expiration dates of four employees’ options. The extension of the expiration date impacted 1,004,667 granted stock options, resulting in incremental stock-based compensation expense of $0.8 million during the year ended December 31, 2023. During the year ended December 31, 2023, the Company accelerated the vesting start dates of two employees’ RSUs. The modification impacted 167,500 previously granted RSUs that were Double-Trigger awards in which the liquidity-based vesting condition was not considered probable at the date of modification. As the liquidity-based vesting condition was met upon the IPO, the impact of the modified RSUs is included in the total stock-based compensation recognized during the year ended December 31, 2023. On April 10, 2023, the Company approved an amendment to the vesting schedule of 4,250,947 RSUs governed by the 2015 Plan. Specifically, the vesting schedule of these RSUs were amended to align with the Company’s standard four quarterly vesting dates that were established on a prospective basis in June of 2022. This modification impacted 657 grantees, and all RSUs that were modified were Double-Trigger awards in which the liquidity-based vesting condition was not considered probable at the date of modification. As the liquidity-based vesting condition was met upon the IPO, the impact of this modification is included in the total stock-based compensation recognized during the year ended December 31, 2023 and is based on the fair value of the award on the date of modification. On March 15, 2023, the Company announced a reduction in workforce that resulted in the termination of approximately 8% of the Company’s full-time workforce (130 employees). As part of the reduction in workforce, the Company modified 608,698 previously granted stock options and 64,301 previously granted RSUs. During the year ended December 31, 2023, the Company incurred an incremental stock-based compensation expense of $0.6 million related to the modification of the stock options modified. All RSUs that were modified were Double-Trigger awards in which the liquidity-based vesting condition was not considered probable at the date of modification. As the liquidity-based vesting condition was met upon the IPO, the impact of the modified RSUs is included in the total stock-based compensation recognized during the year ended December 31, 2023 and is based on the fair value of the award on the date of modification. During the year ended December 31, 2022, the Board approved the modification of an executive’s stock-based awards. At the modification date, the executive had 177,684 RSUs outstanding for which the service-based vesting condition was satisfied but the liquidity-based vesting condition was not. Pursuant to the modification agreement, the Company elected to cancel 63,775 of the unvested RSUs in exchange for $1.5 million, which the Company recorded stock-based compensation as general and administrative expense in the Consolidated Statements of Operations and Comprehensive Loss. Additionally, during the year ended December 31, 2022, the Company recorded incremental stock-based compensation expense of $0.1 million associated with 2,616 stock options granted and 154 RSUs granted to one employee that was terminated but continued to vest in previously issued awards for a limited period after provision of substantive services ceased. During the year ended December 31, 2022, the Company amended the terms of certain stock option awards issued to three employees to add a change of control provision. Such modification did not result in any incremental stock-based compensation expense. The Company also extended the post-termination exercise periods for two terminated employees holding 65,704 stock options. The Company determined the incremental stock-based compensation expense resulting from the modifications was not material. Additionally, the Company provided two terminated employees with accelerated vesting on the service-based vesting condition of 22,029 Double-Trigger RSUs held. Because satisfaction of the liquidity-based vesting condition was not probable, the Company did not record the incremental stock-based compensation expense resulting from the modifications. Such amounts will be recorded upon vesting (that is, upon occurrence of a qualifying liquidity event). During the year ended December 31, 2021, the Board approved a modification to three executives who were terminated during 2021. These modifications resulted in the accelerated vesting of tranches beyond the termination date as well as extension of the exercise window for these employees. The modification covered 1,326,461 options and resulted in incremental stock-based compensation of $9.9 million during the year. Additionally, during the year ended December 31, 2021, the Board approved a modification to a former executive’s stock-based compensation awards who was terminated during 2021. The Company prorated the expense for the years ended December 31, 2022 and 2021, which was $3.8 million and $1.1 million, respectively, as the modification impacted both years presented as services were provided by the employee in both years as part of the terms of the award modification. Secondary Transactions The Company’s employees historically participated in secondary market transactions whereby existing or third-party investors purchased shares owned by the employee associated with previously issued stock-based compensation awards. The Company’s involvement in such secondary market transactions was generally limited to waiving or assigning its right of first refusal over the respective shares. During the years ended December 31, 2023, 2022, and 2021 secondary investors purchased 912,187, 1,002,968, and 4,262,974 shares of common stock from certain employees, respectively. Stock-based compensation expense related to these transactions, representing amounts paid in excess of then current fair value, totaled $0.8 million and $21.5 million and during the year ended December 31, 2022 and 2021, respectively, and is recorded in operating expenses in the accompanying Consolidated Statements of Operations and Comprehensive Loss. No stock-based compensation expense was recorded during the year ended December 31, 2023 related to secondary transactions. Stock-Based Compensation Expense During the year ended December 31, 2023, the Company capitalized $1.3 million of stock compensation expense related to services performed on capitalized software development projects. During the year ended December 31, 2022, the Company did not capitalize any stock compensation expense related to services performed on capitalized software development projects, and during the year ended December 31, 2021 , the Company had an immaterial amount of capitalized stock compensation expense related to services performed on capitalized software development projects. Stock-based compensation included in the Consolidated Statements of Operations and Comprehensive Loss is as follows (in thousands): Year Ended December 31, 2023 2022 2021 Cost of revenue $ 24,973 $ 129 $ 960 Selling and marketing 107,954 985 29,713 Research and development 120,184 1,230 8,193 General and administrative 87,688 5,958 13,123 Stock-based compensation, net of amounts capitalized 340,799 8,302 51,989 Capitalized stock-based compensation expense 1,349 — 2 Total stock-based compensation expense $ 342,148 $ 8,302 $ 51,991 During the year ended December 31, 2022, stock-based compensation expense included $1.5 million paid in cash in exchange for the cancellation of an executive’s unvested RSUs outstanding for which the service-based vesting condition was satisfied but the liquidity-based vesting condition was not. This is included within general and administrative expense in the Company’s Consolidated Statements of Operations and Comprehensive Loss. During the year ended December 31, 2021, stock-based compensation expense included $16.7 million paid in cash for the repurchasing and retirement of common stock, of which $8.8 million is included within selling and marketing expense, $5.8 million within research and development expense, and $2.1 million within general and administrative expense in the Company’s Consolidated Statements of Operations and Comprehensive Loss. As of December 31, 2023, total unrecognized compensation cost related to unvested Options was $0.1 million, which will be recognized on a ratable basis over a weighted-average remaining period of 0.4 years. As of December 31, 2023, total unrecognized compensation cost related to unvested RSUs was $257.5 million, which will be recognized on a ratable basis over a weighted-average remaining period of 3.3 years.

Loss Per Share

Loss Per Share	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Loss Per Share	Loss Per Share Basic net loss per share attributable to Series A and Series B common stockholders is computed by dividing the net loss by the number of weighted-average outstanding common shares. Diluted net loss per share attributable to Series A and Series B common stockholders is determined by giving effect to all potential common equivalents during the reporting period, unless including them yields an antidilutive result, and is calculated using the treasury stock method. The Company considers its warrants, Investment Option, restricted stock units and stock options as potential common equivalents, but excluded them from the computation of diluted earnings per share attributable to common stockholders in the periods presented, as their effect was antidilutive during the years ended December 31, 2023, 2022 and 2021. The rights, including the liquidation and dividend rights, of the holders of Series A and Series B common stock are identical, except with respect to voting and conversion. As the liquidation and dividend rights are identical, the undistributed earnings are allocated on a proportionate basis to each series of common stock and the resulting basic and diluted net loss per share attributable to common stockholders are, therefore, the same for both Series A and Series B common stock on both individual and combined basis. The following table presents the calculation of basic and diluted net loss per share attributable to Series A and Series B common stockholders for the periods presented, (in thousands, except share and per share data): Year Ended December 31, 2023 2022 2021 Net loss per share attributable to Series A and Series B common stockholders, basic and diluted: Numerator: Net loss $ (308,233) $ (49,193) $ (79,393) Denominator: Weighted-average shares - basic and diluted 242,889,272 229,857,206 220,865,179 Net loss per share attributable to Series A and Series B common stockholders, basic and diluted $ (1.27) $ (0.21) $ (0.36) The following table summarizes the potential common shares excluded from the computation of diluted net income (loss) per share: Year Ended December 31, 2023 2022 2021 Warrants outstanding 5,165,732 11,217,017 — Investment Option 15,743,174 15,743,174 — RSUs outstanding 14,690,417 11,712,446 7,430,700 Options outstanding 31,734,725 34,207,554 36,858,706 Restricted stock outstanding — 26,795 62,522 Total 67,334,048 72,906,986 44,351,928

Restructuring Costs

Restructuring Costs	12 Months Ended
	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Restructuring Costs	Restructuring Costs On March 15, 2023, the Company announced a restructuring plan that resulted in a reduction of approximately 8% of the Company’s full time workforce. The Company’s restructuring actions were intended to improve operational efficiencies. Restructuring costs consist primarily of employee severance and related benefits as well as stock-based compensation from the modification of terminated employee stock options. See Note 12. Stock-Based Compensation for further detail on award modifications due to the restructuring. Restructuring costs included in the Consolidated Statements of Operations and Comprehensive Loss is as follows (in thousands): Year ended, December 31, 2023 Cost of revenue $ 1,138 Selling and marketing 1,832 Research and development 3,375 General and administrative 1,532 Total $ 7,877

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net loss	$ (308,233)	$ (49,193)	$ (79,393)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended	12 Months Ended
	Dec. 31, 2023 shares	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Amanda Whalen [Member]
Trading Arrangements, by Individual
Name	Amanda Whalen
Title	Chief Financial Officer
Adoption Date	November 16, 2023
Arrangement Duration	366 days
Aggregate Available	105,000	105,000
Landon Edmond [Member]
Trading Arrangements, by Individual
Name	Landon Edmond(1)
Title	Chief Legal Officer and General Counsel
Adoption Date	November 17, 2023
Arrangement Duration	366 days
Aggregate Available	258,668	258,668
Allen Chaves [Member]
Trading Arrangements, by Individual
Name	Allen Chaves
Title	Chief Technology Officer
Adoption Date	November 21, 2023
Arrangement Duration	367 days
Aggregate Available	780,000	780,000
Susan St. Ledger [Member]
Trading Arrangements, by Individual
Name	Susan St. Ledger
Title	Director
Adoption Date	December 11, 2023
Arrangement Duration	536 days
Aggregate Available	10,500	10,500
Jennifer Ceran [Member]
Trading Arrangements, by Individual
Name	Jennifer Ceran
Title	Director
Adoption Date	December 14, 2023
Arrangement Duration	368 days
Aggregate Available	13,000	13,000
Officer Trading Arrangement [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		During the three months ended December 31, 2023, the Company’s directors and officers (as defined in Rule 16a-1(f) under the Exchange Act) adopted written plans intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) of the Exchange Act for the sale of the Company’s securities as set forth in the table below. Name Position Adoption Date Total Shares Subject to Trading Arrangement Expiration Date Amanda Whalen Chief Financial Officer November 16, 2023 105,000 November 16, 2024 Landon Edmond (1) Chief Legal Officer and General Counsel November 17, 2023 258,668 November 17, 2024 Allen Chaves Chief Technology Officer November 21, 2023 780,000 November 22, 2024 Susan St. Ledger Director December 11, 2023 10,500 May 30, 2025 Jennifer Ceran Director December 14, 2023 13,000 December 16, 2024 ______________ (1) The actual number of shares of common stock sold pursuant to this plan will be less, after shares are withheld to satisfy tax withholding obligations in connection with the net settlement of equity awards.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions are eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Significant items subject to such estimates and assumptions include, but are not limited to, the allowance for doubtful accounts, determination of revenue recognition under ASC 606, estimated benefit period of deferred contract acquisition costs, estimated life of prepaid marketing expense, and historical valuation of common stock and stock-based compensation, including fair value of the investment option and warrants. The Company evaluates estimates based on historical and anticipated results, trends, and various other assumptions. The Company assesses these estimates on a regular basis; however, actual results could differ from these estimates.
Segment Information	Segment Information Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined that it operates in one operating segment and one reportable segment as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance.
Revenue Recognition, Deferred Revenue and Deferred Contract Acquisition Costs	Revenue Recognition The Company provides a SaaS solution for personalized email and SMS marketing services through a cloud-based analytics platform. The core functionalities of the software are segmentation of users’ customer lists to facilitate targeted messaging via email and SMS and the use of data science and analytics to evaluate historical sales and predict consumer activity. Revenues are derived primarily from subscription revenues, which are comprised of subscription fees from customers accessing its hosted platform services for targeted messaging. Contractual subscriptions for customers generally auto-renew on either a monthly, quarterly, or annual basis, and customers may elect not to renew by providing at least five days’ advance notice for contracts on a monthly billing cycle and thirty days’ advance notice for contracts with any other billing cycle. The customer does not have the right to take possession of the Company’s software. Subscription pricing is determined based on a customer’s profile and messaging count and monthly messaging quantities and is considered fixed, based on a tiered pricing structure. Variable consideration in the Company’s contracts is not material but represents the overage charges incurred by customers who exceed their allotments. The Company recognizes revenue under the core principle to depict the transfer of control to the Company’s customers in an amount reflecting the consideration to which the Company expects to be entitled. In order to achieve that core principle, the Company evaluates its revenue arrangements under the five-step model as follows: (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when or as the Company satisfies a performance obligation. Typically, the SaaS subscription contracts consist of a single performance obligation, and revenue is recognized over time as the performance obligation is satisfied. The performance obligation is deemed to be satisfied ratably as the customer simultaneously receives and consumes the services that the Company performs and typically have the same term. Due to the term of a majority of the Company’s contracts being less than one year, the Company has determined a significant financing component does not exist. The Company accounts for individual performance obligations separately if they have been determined to be distinct (i.e., the services are separate if identifiable from other items in the arrangement and the customer can benefit from them on their own or with other resources that are readily available to the customer). The transaction price is allocated to the distinct performance obligations on a relative stand-alone selling price basis. Stand-alone selling prices are determined based on the prices at which the Company separately sells subscriptions. Sales taxes collected from customers and remitted to government authorities are excluded from revenue. The Company incurs fees based on transaction volume and dollars processed through its credit card processor which are classified as general and administrative expense. Through the Company’s credit card processor, all receivables related to credit cards are collected within three business days. Deferred Revenue Deferred revenue primarily consists of billings in advance of revenue recognition from subscription services and is recognized as the revenue recognition criteria is met. The Company generally bills its subscription customers monthly on the first day of the subscription term. Deferred revenue that is expected to be recognized during the succeeding 12-month period is recorded as deferred revenue. Deferred Contract Acquisition Costs Deferred contract acquisition costs are incremental costs incurred in connection with acquiring a customer contract and consists primarily of sales commissions and the associated payroll taxes. The Company expects to benefit from those costs for more than one year as the Company primarily pays sales commissions on the initial contract, and there are no commensurate commissions paid on contract renewals.
Cost of Revenue	Cost of Revenue Cost of revenue consists of costs related to supporting and hosting the Company’s software platform and channel offering for paying customers. These costs primarily include cloud-based infrastructure costs, outbound communication sending costs, employee-related costs including payroll, benefits, bonuses, and stock-based compensation expense related to the customer support team, amortization of capitalized internal-use software development costs, and allocated overhead costs, including rent, facilities, depreciation, and costs related to information technology.
Shopify Collaboration Agreement	Shopify Collaboration Agreement On July 28, 2022, the Company entered into a collaboration agreement with Shopify Inc. and certain of its affiliates (collectively, “Shopify”) to form a strategic relationship for the purposes of creating greater interoperability between the Klaviyo and Shopify platforms and forming a strategic product, distribution, and marketing relationship. Shopify became a related party upon execution of this agreement. The collaboration agreement has a term of 7 years and automatically renews for successive one-year periods unless the Company or Shopify provides written notice of non-renewal. In connection with the collaboration agreement, the Company entered into 3 separate agreements including a revenue sharing agreement, common stock warrant agreement, and stock purchase agreement. Under the revenue sharing agreement, the Company will make payments to Shopify in exchange for marketing services received under the collaboration agreement, which are comprised of payments for the Shopify Core Revenue Share and payments for the Shopify Plus Integration Fee. These payments are calculated as follows: • Shopify Core Revenue Share: For all revenue generated through the use of the Company’s email and SMS marketing applications by Shopify merchants designated as “Shopify Core Merchants” in respect of leads attributed to Shopify, the Company is obligated to pay Shopify a percentage of such revenues or the amounts owed to Shopify under the terms of Shopify’s standard partnership agreements applicable to all Shopify partners, which is 15% of any revenues exceeding a $1 million threshold. • Shopify Plus Integration Fee : On a monthly basis, the Company is required to pay Shopify a fee (“Shopify Plus Integration Fee” or “Integration Fee”), subject to an annual increase at Shopify’s election (up to a maximum increase of not more than a percentage calculated through a formula provided in the revenue sharing agreement), with respect to each Shopify Plus Merchant where all of the following circumstances apply: (a) the Shopify Plus Merchant was on Shopify’s Plus program at the end of the relevant month; (b) one or more of the Shopify Plus Merchant’s covered stores has the Company’s application installed at both the beginning and at the end of the relevant month; and (c) the Company’s application received a webhook request and/or made any Application Programming Interface calls against one or more of the Shopify Plus Merchant’s covered stores in the relevant month (i.e., the Company’s application is integrated with the Shopify platform and data is flowing between them). The Company determined that Shopify is a vendor and not a customer, as the collaboration agreement is a services contract under which the Company is receiving marketing services from Shopify in exchange for payments under the revenue sharing agreement. The revenue sharing agreement is a mechanism for Shopify to be compensated for the customer acquisition and marketing services Shopify is providing to the Company. Shopify is not a reseller or distributor of the Company’s Platform, nor does Shopify provide any services on the Company’s behalf. During the year ended December 31, 2023, the Company incur red $21.9 million related to fees paid under the revenue sharing agreement. During the year ended December 31, 2022, the Company incurred an aggregate of $16.2 million fees paid to Shopify pursuant to revenue sharing arrangements, inclusive of $7.7 million paid to Shopify pursuant to the terms of the Shopify revenue sharing agreement and $8.5 million paid to Shopify pursuant to the terms of our prior agreement with Shopify that was in place prior to, and replaced by, the Shopify revenue sharing agreement. As of December 31, 2023 and 2022 , the Company had $4.5 million and $2.7 million, respectively, in accrued expenses owed to Shopify for fees payable under the revenue sharing agreement. As consideration for the collaboration agreement, the Company also issued warrants that allow Shopify to purchase up to 15,743,174 shares of common stock at a price of $0.01 per share, of whic h 25% of the warrants vested on the grant date on July 28, 2022, and the remaining 75% of the warrants vest quarterly over the remaining 5 year period. The aggregate grant date fair value of the warrants was $370.3 million and will be capitalized to prepaid marketing expense as the warrants vest. The prepaid marketing ex pense asset is amortized into selling and marketing expense on a straight-line basis over the expected benefit period, which is the 7 year term of the collaboration agreement . Pursuant to the common stock warrant agreement, upon the Company’s IPO, 25% of the total number of warrants were accelerated, and the remaining unvested portion vests quarterly over the remaining term. During the years ended December 31, 2023 and 2022, the Company capitalized prepaid marketing expense of $142.3 million and $106.5 million related to the vested warrants, respectively. For the years ended December 31, 2023 and 2022 , the Company recorded marketing expense o f $52.9 million and $22.0 million, respectively, in the Consolidated Statements of Operations and Comprehensive Loss as a component of selling and marketing expense related to the amortization of the prepaid marketing expense. As of December 31, 2023 and 2022, the Company’s prepaid marketing expense is $173.8 million and $84.4 million, respectively. As of December 31, 2023 , there is $295.4 million of unrecognized marketing expense related to the warrants that will be recognized over 5.6 years. Refer to Note 11. Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) for further discussion of the warrants. On June 24, 2022, the Company entered into a stock purchase agreement with Shopify. On the closing date of July 28, 2022, Shopify purchased 2,951,846 shares of common stock for $33.88 per share. The stock purchase agreement gives Shopify the right to purchase 15,743,174 additional shares of common stock for $88.93 per share (the “Investment Option”). The common stock and Investment Option were determined to be freestanding financial instruments purchased at fair value and were accounted for separately from the collaboration agreement, revenue sharing agreement, and common stock warrant. Refer to Note 11. Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) for further discussion of the common stock purchase and Investment Option.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred, unless they qualify as capitalized internal-use software development costs. Research and development costs consist primarily of personnel-related expenses associated with the Company’s research and development staff, including salaries, benefits, bonuses, and stock-based compensation.
Advertising Costs	Advertising Costs
Stock-Based Compensation and Non-Vested Restricted Common Stock	Stock-Based Compensation The Company recognizes stock-based compensation on awards granted under two stock compensation plans, which are described in more detail in Note 12. Stock-Based Compensation . The Company measures stock-based compensation awards, including stock options and RSUs, based on the estimated fair value of the awards on the date of grant. Stock-based compensation expense is recorded for awards issued to employees and non-employees at fair value with a corresponding increase in additional paid-in capital. For awards with service conditions only, the Company recognizes compensation expense on a straight-line basis over the requisite service period of the award. Forfeitures are recognized when they occur. RSUs granted under the Company’s 2015 Stock Incentive Plan are subject to both service-based and performance-based vesting conditions, whereby the performance condition is satisfied upon occurrence of a liquidity event. Compensation cost related to awards with liquidity-based vesting conditions has been recognized through December 31, 2023, as the Company’s registration statement on Form S-1 filed with the SEC in connection with the IPO became effective on September 19, 2023, which satisfied the liquidity-based vesting condition of the Double-Trigger RSUs. Compensation expense for these awards with both a service and performance condition are expensed under the accelerated attribution method which includes a cumulative catch up recorded upon the IPO for services that had been completed as of the IPO. The remaining expense for these awards is recognized using the accelerated attribution method over the remaining service period. The fair value of each RSU grant is calculated based on the estimated fair value of the Company’s common stock on the date of grant, or, if modified, the date of modification. RSUs granted under the Company’s 2023 Stock Option and Incentive Plan are for shares of Series A common stock and are currently subject to service-based vesting conditions only. Compensation costs related to these awards are recognized using the straight-line method over the service period of the award. The fair value of each RSU grant is calculated based on the fair value of the Company’s Series A common stock on the date of grant, or, if modified, the date of modification. Until our IPO, given the absence of an active market for the Company’s common stock, management and the Company’s Board of Directors (the “Board”) were required to estimate the fair value of the Company’s common stock at the time of each grant of a stock-based compensation award. The Company and the Board utilized various valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants’ Technical Practice Aid, Valuation of Privately Held Company Equity Securities Issued as Compensation to estimate the fair value of its common stock. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors in determining the value of the Company’s common stock at each grant date, including the following factors: • prices paid for the Company’s capital stock, which the Company has sold to outside investors in arm’s-length transactions, considering the rights and privileges of the securities sold relative to the common stock; • prices paid for shares of its common stock sold in secondary market transactions; • valuations performed by an independent valuation specialist; • the Company’s stage of development and revenue growth; • the market performance of comparable publicly traded companies; • adjustments necessary to recognize a lack of marketability for the common stock underlying the granted options and RSUs; • the likelihood of achieving a liquidity event for the common stock underlying the stock-based awards, such as an IPO or sale of the Company, given prevailing market conditions; and • the U.S. and global economic and capital market conditions and outlook. Following the Company’s IPO, there is an active market for its Series A common stock which is utilized to measure the fair value of the Company’s underlying shares. Non-Vested Restricted Common Stock The Company may grant non-vested restricted common stock to employees, directors, and consultants with or without cash consideration. These grants contain certain restrictions on the sale of the shares. Non-vested restricted common stock are considered issued, but not outstanding, for accounting purposes until they vest. Upon termination of the relationship with a holder of the non-vested restricted common stock, the Company has the right to repurchase the non-vested restricted common stock at the price paid by the holder or, if there was no consideration, a price per share as defined in the Company’s agreement with the holder of the restricted common stock. All restricted common stock was vested as of December 31, 2023.
Redeemable Common Stock	Redeemable Common Stock Redeemable common stock represents shares of the Company’s common stock that are redeemable at the option of the investor after a specified date. The initial carrying amount of redeemable common stock is equal to the respective issuance date fair value of the common stock subject to redemption, less issuance costs. The carrying amount is adjusted to equal the redemption value, which is equal to the fair value of a single share of common stock at the end of each reporting period. The carrying amount is subject to a floor equal to the initial carrying amount. The resulting changes in the redemption value are recorded with corresponding adjustments against retained earnings, if available, additional paid-in capital or accumulated deficit. Redeemable common stock is classified outside of permanent equity on the Consolidated Balance Sheets as the redemption option is outside of the Company’s control. As the redemption feature applicable to certain shares of the Company’s common stock was terminated upon the IPO, all shares of the Company’s redeemable common stock converted into 64,046,223 shares of Series B common stock upon the effectiveness of the Company’s registration statement on Form S-1 filed with the SEC on September 19, 2023. Refer to Note 11. Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) for further discussion.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with ASC 740, Income Taxes (“ASC 740”), which utilizes the asset and liability method for the financial accounting and reporting of income taxes. Under this method, deferred income taxes are recognized for the expected future tax consequences of differences between the tax bases of assets and liabilities and their reported amounts in the financial statements. The amount of any future tax benefit associated with deferred tax assets is reduced by a valuation allowance when there is uncertainty that those tax benefits will be realized. The Company accounts for uncertain tax positions using a more-likely-than-not recognition threshold in accordance with ASC 740. The evaluation of uncertain tax positions is based on factors including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken in tax returns, the effective settlement of matters subject to audit, new audit activity, and changes in facts or circumstances related to a tax position. Interest and penalties related to uncertain tax positions are included as a component of income tax expense.
Accounts Receivable	Accounts Receivable Accounts receivable are shown net of an allowance for doubtful accounts of $1.5 million and $2.3 million as of December 31, 2023 and 2022, respectively. The allowance for doubtful accounts is established to represent the Company’s best estimate of the net realizable value of the outstanding amount of receivables that it will be unable to collect. The development of the Company’s allowance for doubtful accounts is based on a review of factors such as the customer’s payment history, historical loss patterns, the general economic climate, age, and past due status of invoices. If circumstances relating to specific customers change or unanticipated changes occur in the general business environment, the Company’s estimates of the recoverability of receivables could be further adjusted. The allowance for doubtful accounts consists of the following activity (in thousands): Year Ended December 31, 2023 2022 2021 Balance at beginning of the period $ 2,253 $ 1,917 $ 125 Provisions for uncollectible accounts, net of recoveries 28 1,224 1,792 Write offs (802) (888) — Balance at end of the period $ 1,479 $ 2,253 $ 1,917
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with a remaining maturity of three months or less when purchased to be cash equivalents. As of December 31, 2023, the Company had cash equivalents of $314.5 million in money market funds. As of December 31, 2022, the Company did not have cash equivalents. As of December 31, 2023 and 2022, the Company had a current restricted cash balance of $0.4 million and $0.4 million, respectively. As of December 31, 2023 and 2022, the Company had a non-current restricted cash balance of $0.7 million and $0.7 million, respectively. Restricted cash at December 31, 2023 and 2022 related to the Company’s required collateral to fund payroll and credit card obligations in its Australian entity as well as collateral required to be held as a result of the Company’s office lease in Australia. Restricted cash is included in current assets for obligations that expire within one year and is included in non-current assets for assets that expire more than one year from the balance sheet date.
Concentrations of Credit Risk, Significant Customers, and Vendors	Concentrations of Credit Risk, Significant Customers, and Vendors Financial instruments that potentially expose the Company to concentration of credit risk consist primarily of cash, restricted cash, and accounts receivable. The Company maintains its cash and restricted cash at accredited financial institutions. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000. As of December 31, 2023 and 2022, the Company’s primary operating accounts significantly exceeded federally insured limits. The Company does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. Credit risk with respect to accounts receivable is dispersed due to the Company’s large number of customers. The Company routinely assesses the creditworthiness of its customers. The Company does not require collateral. The Company maintains an allowance for potentially uncollectible accounts receivable. Accounts receivable is stated at the amount management expects to collect from outstanding balances. Due to these factors, no additional credit risk beyond amounts provided for collection losses is believed by management to be probable in the Company’s accounts receivable. Significant concentrations of credit risk constitute customers that represent 10% or more of accounts receivable. As of December 31, 2023 and 2022, no individual customer accounted for more than 10% of accounts receivable. Additionally, there were no customers that represented 10% or more of the Company’s revenue for the fiscal years ended December 31, 2023, 2022, and 2021.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost and depreciated over the estimated useful lives of the related assets using the straight-line method. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation, are removed from the accounts, and any resulting gain or loss is included in the determination of net income or loss in the period of retirement. Expenditures for maintenance and repairs are charged to expense as incurred, whereas major improvements are capitalized as additions to property and equipment. The estimated useful lives of the Company’s property and equipment are as follows: Office equipment 5 years Computer equipment 3 years Furniture and fixtures 5 years Leasehold improvements Lesser of lease term or useful life Asset retirement cost Lesser of lease term or 5 years
Asset Retirement Obligations ("ARO")	Asset Retirement Obligations (“ARO”) As part of the build out of the Company’s headquarters in Boston, Massachusetts, the Company built an internal staircase connecting multiple floors. This staircase required the removal of ground space to connect the floors. The lease agreement requires the Company to incur the costs required to restore the leased space to its original condition. During fiscal year 2020, on the lease commencement date, the Company established an ARO based on the present value of
Capitalized Internal-Use Software	Capitalized Internal-Use Software The Company capitalizes qualifying costs incurred during the application development stage in connection with the development of internal-use software, which are included on the Consolidated Balance Sheets as a component of property and equipment, net. Costs related to preliminary project activities and post-implementation stages of software development are expensed as incurred. Costs capitalized as internal-use software development costs include eligible salaries, stock-based compensation, and other compensation-related costs of employees and costs incurred in developing new features and enhancements when the costs will result in additional functionality. Capitalized internal-use software development costs are amortized on a straight-line basis over their estimated useful life of 3 years. Computer software development costs that do not qualify for capitalization are expensed as incurred. Capitalization begins when the preliminary project stage is complete, management authorizes and commits to the funding of the software project with appropriate authority, it is probable the project will be completed, the software will be used to perform the functions intended, and certain functional and quality standards have been met.
Leases	Leases The Company determines whether an arrangement contains a lease at inception. At the commencement date, the Company will perform the classification tests to determine whether its leases are operating or financing and recognize the related lease liability and right-of-use (“ROU”) asset. The Company, as the lessee, recognizes in the Consolidated Balance Sheets a liability to make lease payments and an ROU asset representing the right to use the underlying asset for both finance and operating leases with a lease term longer than twelve months. Lease liabilities and their corresponding ROU assets are recognized based on the present value of unpaid lease payments over the expected lease term. The Company has elected the following practical expedients: (1) not to separate lease and non- lease components for all asset classes and (2) not to recognize leases with a term of 12 months or less on the Consolidated Balance Sheets for all asset classes. The Company leases office space and office equipment under non-cancelable operating leases ranging from 1 to 8 years. Certain leases include options to extend the leases for up to 5 years. These options will be included in the lease term when they are reasonably certain to be exercised. The Company’s leases generally do not include options to terminate the leases or to purchase the underlying asset. The Company’s leases are primarily fixed payments. Certain of the Company’s leases include variable lease payments, generally related to the lessor’s operating costs associated with the underlying asset, which are expensed as incurred. The Company’s leases generally do not contain residual value guarantees. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate (“IBR”) to calculate the present value of future minimum lease payments, which is the estimated rate the Company would be required to pay for fully collateralized borrowing over the period similar to lease terms. Lease expense for minimum lease payments is recognized on a straight-line basis over the lease term.
Foreign Currency Translation	Foreign Currency Translation The functional currency of the Company’s foreign subsidiaries is the U.S. dollar (“USD”). In certain instances, the Company enters into transactions that are denominated in a currency other than the USD. At the date that such transaction is recognized, each asset, liability, revenue, expense, gain, or loss arising from the transaction is measured and recorded in USD using the exchange rate in effect at that date. At each balance sheet date, recorded monetary balances denominated in a currency other than the USD are adjusted to USD using the exchange rate at the balance sheet date, with gains or losses recognized in other, net in the consolidated statements of operations. Foreign currency translation gains and losses were immaterial for the periods presented.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities are carried at fair value in accordance with Accounting Standards Codification ASC 820, Fair Value Measurement (“ASC 820”). Fair value is defined as the price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The guidance establishes a fair value hierarchy that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy are as follows: • Level 1 – Quoted prices in active markets for identical assets or liabilities • Level 2 – Observable inputs (other than level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. As of December 31, 2023 and 2022, the Company’s carrying amounts of financial instruments, including cash, restricted cash, accounts receivable, accounts payable, and accrued liabilities approximate their fair values due to their short-term maturities. Certain non-financial assets, such as intangible assets, right of use assets, and property and equipment, are measured at fair value on a non-recurring basis and are adjusted to fair value only if an impairment charge is recognized. Such fair value measures are considered to be within the Level 3 valuation hierarchy due to the subjective nature of the unobservable inputs used. The Company has not recorded any impairment charges during any of the periods presented.
Loss Per Share	Loss Per Share In accordance with FASB ASC 260, Earnings Per Share , the basic net loss per share attributable to Series A and Series B common stockholders is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during the applicable period. Diluted net loss per share attributable to Series A and Series B common stockholders is computed in the same manner as basic net income loss per share as the inclusion of all potentially dilutive securities outstanding would be antidilutive. See Note 13. Loss Per Share for further information. Basic net loss per share attributable to Series A and Series B common stockholders is computed by dividing the net loss by the number of weighted-average outstanding common shares. Diluted net loss per share attributable to Series A and Series B common stockholders is determined by giving effect to all potential common equivalents during the reporting period, unless including them yields an antidilutive result, and is calculated using the treasury stock method. The Company considers its warrants, Investment Option, restricted stock units and stock options as potential common equivalents, but excluded them from the computation of diluted earnings per share attributable to common stockholders in the periods presented, as their effect was antidilutive during the years ended December 31, 2023, 2022 and 2021. The rights, including the liquidation and dividend rights, of the holders of Series A and Series B common stock are identical, except with respect to voting and conversion. As the liquidation and dividend rights are identical, the undistributed earnings are allocated on a proportionate basis to each series of common stock and the resulting basic and diluted net loss per share attributable to common stockholders are, therefore, the same for both Series A and Series B common stock on both individual and combined basis.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets
Recent Accounting Pronouncements	Recent Accounting Pronouncements The Company has implemented all applicable accounting pronouncements that are in effect. In November 2023, the FASB issued Accounting Standards Update ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures , which requires disclosure of incremental segment information on an interim and annual basis. This ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal periods beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. The Company is currently evaluating the impact of the guidance on the consolidated financial statements and disclosures. There are no other new accounting pronouncements that have been issued that would have a material impact on its financial position or results of operations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2023
Accounting Policies [Abstract]
Schedule of Allowance for Doubtful Accounts	The allowance for doubtful accounts consists of the following activity (in thousands): Year Ended December 31, 2023 2022 2021 Balance at beginning of the period $ 2,253 $ 1,917 $ 125 Provisions for uncollectible accounts, net of recoveries 28 1,224 1,792 Write offs (802) (888) — Balance at end of the period $ 1,479 $ 2,253 $ 1,917
Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported in the Consolidated Balance Sheets to the total of the amounts reported in the Consolidated Statements of Cash Flow (in thousands): As of, December 31, 2023 December 31, 2022 Cash and cash equivalents $ 738,562 $ 385,820 Restricted cash - current 409 409 Restricted cash - non-current 686 687 Total cash, cash equivalents, and restricted cash $ 739,657 $ 386,916
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported in the Consolidated Balance Sheets to the total of the amounts reported in the Consolidated Statements of Cash Flow (in thousands): As of, December 31, 2023 December 31, 2022 Cash and cash equivalents $ 738,562 $ 385,820 Restricted cash - current 409 409 Restricted cash - non-current 686 687 Total cash, cash equivalents, and restricted cash $ 739,657 $ 386,916
Schedule of Property and Equipment	The estimated useful lives of the Company’s property and equipment are as follows: Office equipment 5 years Computer equipment 3 years Furniture and fixtures 5 years Leasehold improvements Lesser of lease term or useful life Asset retirement cost Lesser of lease term or 5 years Property and equipment consist of the following (in thousands): As of, December 31, 2023 December 31, 2022 Capitalized internal-use software $ 11,682 $ 4,460 Office equipment 3,633 3,203 Computer equipment 2,939 639 Furniture and fixtures 7,242 6,683 Leasehold improvements 45,768 45,228 Construction-in-progress 78 82 Asset retirement cost 643 643 Total property and equipment 71,985 60,938 Less accumulated depreciation and amortization (28,535) (15,101) Total property and equipment, net $ 43,450 $ 45,837

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenue by Geographic Area	Revenue by geographic area, based on the location of the Company’s customers, was as follows (in thousands): Year Ended December 31, 2023 2022 2021 Americas: United States $ 443,471 $ 307,222 $ 197,263 Other Americas (1) 38,180 26,790 15,758 APAC (1)(2) 72,797 47,905 27,574 EMEA (1)(3) 143,651 90,831 50,045 Total Revenue $ 698,099 $ 472,748 $ 290,640 (1) Other than the United States, no other individual country accounted for 10% or more of total revenue for any of the periods presented. (2) Asia-Pacific (3) Europe, the Middle East and Africa
Schedule of Changes of Deferred Revenue	The following table summarizes the changes in the balance of deferred revenue during the periods presented (in thousands): Year Ended December 31, 2023 2022 Balance at beginning of the period $ 25,109 $ 15,092 Plus: Billings during the period 713,090 482,765 Less: Revenue recognized during the period (698,099) (472,748) Balance at end of the period $ 40,100 $ 25,109

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured on Recurring Basis	The following table sets forth the Company’s financial instruments that were measured at fair value on a recurring basis at the periods indicated below, by level within the fair value hierarchy (in thousands): As of December 31, 2023 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 314,511 $ — $ — $ 314,511 Total $ 314,511 $ — $ — $ 314,511

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	The estimated useful lives of the Company’s property and equipment are as follows: Office equipment 5 years Computer equipment 3 years Furniture and fixtures 5 years Leasehold improvements Lesser of lease term or useful life Asset retirement cost Lesser of lease term or 5 years Property and equipment consist of the following (in thousands): As of, December 31, 2023 December 31, 2022 Capitalized internal-use software $ 11,682 $ 4,460 Office equipment 3,633 3,203 Computer equipment 2,939 639 Furniture and fixtures 7,242 6,683 Leasehold improvements 45,768 45,228 Construction-in-progress 78 82 Asset retirement cost 643 643 Total property and equipment 71,985 60,938 Less accumulated depreciation and amortization (28,535) (15,101) Total property and equipment, net $ 43,450 $ 45,837
Schedule of Change in Asset Retirement Obligation	The asset retirement obligation is included in other non-current liabilities on the Consolidated Balance Sheets. Asset retirement obligation activity is as follows (in thousands): Year Ended December 31, 2023 2022 Beginning balance $ 722 $ 685 Additions — — Accretion 39 37 Ending balance $ 761 $ 722

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	The following table presents components of accrued expenses (in thousands): As of, December 31, 2023 December 31, 2022 Accrued compensation and employee related costs $ 25,644 $ 16,926 Accrued sabbatical 3,394 — Accrued value added tax 7,530 4,937 Other accrued taxes 6,830 1,754 Accrued cost of revenue 6,656 7,923 Accrued professional services 3,605 2,297 Accrued marketing 6,374 980 Other accrued expenses 2,805 1,309 Total accrued expenses $ 62,838 $ 36,126

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments	Future minimum payments under the Company’s non-cancellable purchase commitments as of December 31, 2023, are presented in the table below (in thousands): Year Ending December 31, Contractual Commitments 2024 $ 117,668 2025 116,965 2026 70,761 2027 40,833 2028 — Total Contractual Commitments: $ 346,227

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Components of Lease Expense	The components of lease expense are as follows (in thousands): Year Ended December 31, 2023 2022 2021 Operating lease cost $ 12,618 $ 12,091 $ 10,517 Short-term lease cost 630 121 — Financing lease cost 21 21 16 Total lease cost $ 13,269 $ 12,233 $ 10,533 Supplemental cash flow information and non-cash activity related to the Company’s leases are as follows (in thousands): Year Ended December 31, 2023 2022 2021 Cash paid for operating lease liabilities, net of tenant incentives received $ 15,197 $ 9,272 $ 10,824 ROU assets recognized for new leases and amendments (non-cash) $ 1,299 $ 3,452 $ 6,132 Other information related to leases is as follows: As of, December 31, 2023 December 31, 2022 Weighted average remaining lease term 4.1 years 5.0 years Weighted average discount rate 4.97 % 4.96 %
Supplemental Balance Sheet Information Related to Operating Leases	Supplemental balance sheet information related to the Company’s operating leases is as follows (in thousands): As of, December 31, 2023 December 31, 2022 Operating lease ROU assets $ 36,987 $ 45,695 Operating lease liabilities, current 14,081 14,864 Operating lease liabilities, non-current 37,498 47,544 Total lease liabilities $ 51,579 $ 62,408
Schedule of Future Undiscounted Annual Cash Flows for Operating Leases	Future undiscounted annual cash flows for the Company’s operating leases as of December 31, 2023 are as follows (in thousands): Year Ending December 31, Operating Leases 2024 $ 14,383 2025 13,237 2026 13,429 2027 12,692 2028 3,205 Thereafter — Total future undiscounted lease payments 56,946 Less imputed interest (5,367) Total lease liabilities $ 51,579

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	The domestic and foreign components of loss before income taxes are as follows (in thousands): Year Ended December 31, 2023 2022 2021 United States $ (312,759) $ (51,729) $ (80,260) Foreign 5,718 2,619 1,186 Loss before income taxes $ (307,041) $ (49,110) $ (79,074)
Schedule of Components of Income Tax Expense (Benefit)	The provision (benefit) for income taxes contained the following components (in thousands): Year Ended December 31, 2023 2022 2021 Current: Federal $ — $ — $ — State (26) 99 45 Foreign 4,652 56 179 4,626 155 224 Deferred: Federal — (95) — State — (16) — Foreign (3,434) 39 95 (3,434) (72) 95 Provision for income taxes $ 1,192 $ 83 $ 319
Schedule of Effective Income Tax Rate Reconciliation	Year Ended December 31, 2023 2022 2021 U.S. federal taxes at statutory rate 21.0 % 21.0 % 21.0 % State taxes, net of federal benefit 4.3 4.4 4.8 Federal research and development credits 3.8 10.3 7.9 State research and development credits 0.9 7.8 3.2 Permanent items (0.4) (1.0) (0.2) Stock-based compensation 1.6 5.6 5.0 Foreign rate differential — — — Non-deductible officers compensation (2.3) — — Prepaid marketing expense 3.6 — — Other — (0.8) 0.1 Change in valuation allowance (32.9) (47.5) (42.2) Total (0.4) % (0.2) % (0.4) %
Schedule of Deferred Tax Assets and Liabilities	The carryforwards and temporary differences that give rise to a significant portion of the Company’s deferred tax assets and liabilities as of December 31, 2023 and 2022, are as follows (in thousands): Year Ended December 31, 2023 2022 Deferred tax assets: Net operating loss carryforwards $ 88,200 $ 49,093 Research and development credits 36,217 21,829 Stock-based compensation 32,204 1,218 Lease liability 12,933 17,225 Capitalized research and development 63,701 21,728 Other 5,553 2,864 Total deferred tax assets 238,808 113,957 Deferred tax liabilities: Depreciation (3,543) (5,481) Deferred commissions (7,657) (5,451) Amortization (2,049) (85) ROU asset (9,303) (13,202) Prepaid marketing expense (43,084) (20,666) Total deferred tax liabilities (65,636) (44,885) Valuation allowance (170,076) (69,205) Net deferred tax assets (liabilities) $ 3,096 $ (133)

Redeemable Common Stock, Comm_2

Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Schedule of Warrant Activity	The following table summarizes the warrants activity during the year ended December 31, 2023: Number of Shares Weighted Average Exercise Price Weighted Average Remaining Life (years) Warrants outstanding at December 31, 2022 11,217,017 $ 0.01 9.57 Granted — — — Exercised (6,051,285) 0.01 8.95 Cancelled — — — Warrants outstanding at December 31, 2023 5,165,732 $ 0.01 8.58
Schedule of Restricted Common Stock Activity	The following is a summary of the non-vested restricted common stock activity during the year ended December 31, 2023: Number of Shares Weighted Average Grant Date Unvested and outstanding at December 31, 2022 26,795 $ 2.84 Granted — — Vested (26,795) $ 2.84 Unvested and outstanding at December 31, 2023 — $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Option Activity	Option activity for the year ended December 31, 2023 is as follows (in thousands, except per share data): Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding at January 1, 2023 34,207,554 $ 0.61 3.74 $ 781,247 Exercised (2,419,308) 1.56 Forfeited and expired (53,521) 3.22 Outstanding at December 31, 2023 31,734,725 $ 0.54 2.65 $ 864,605 Exercisable at December 31, 2023 31,639,454 0.53 2.64 $ 862,297 Expected to vest at December 31, 2023 31,734,725 0.54 2.65 $ 864,605
Schedule of Restricted Stock Unit Activity	Restricted stock unit activity for the year ended December 31, 2023 is as follows (in thousands, except per share data): Number of Units Weighted Average Grant Date Unvested and outstanding at January 1, 2023 11,712,446 $ 30.24 Granted 11,896,929 26.23 Vested (7,206,386) 29.49 Forfeited (1,712,572) 29.51 Unvested and outstanding at December 31, 2023 14,690,417 $ 27.44
Schedule of Stock-Based Compensation Expense	Stock-based compensation included in the Consolidated Statements of Operations and Comprehensive Loss is as follows (in thousands): Year Ended December 31, 2023 2022 2021 Cost of revenue $ 24,973 $ 129 $ 960 Selling and marketing 107,954 985 29,713 Research and development 120,184 1,230 8,193 General and administrative 87,688 5,958 13,123 Stock-based compensation, net of amounts capitalized 340,799 8,302 51,989 Capitalized stock-based compensation expense 1,349 — 2 Total stock-based compensation expense $ 342,148 $ 8,302 $ 51,991

Loss Per Share (Tables)

Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Schedule of Loss Per Share, Basic and Diluted	The following table presents the calculation of basic and diluted net loss per share attributable to Series A and Series B common stockholders for the periods presented, (in thousands, except share and per share data): Year Ended December 31, 2023 2022 2021 Net loss per share attributable to Series A and Series B common stockholders, basic and diluted: Numerator: Net loss $ (308,233) $ (49,193) $ (79,393) Denominator: Weighted-average shares - basic and diluted 242,889,272 229,857,206 220,865,179 Net loss per share attributable to Series A and Series B common stockholders, basic and diluted $ (1.27) $ (0.21) $ (0.36)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table summarizes the potential common shares excluded from the computation of diluted net income (loss) per share: Year Ended December 31, 2023 2022 2021 Warrants outstanding 5,165,732 11,217,017 — Investment Option 15,743,174 15,743,174 — RSUs outstanding 14,690,417 11,712,446 7,430,700 Options outstanding 31,734,725 34,207,554 36,858,706 Restricted stock outstanding — 26,795 62,522 Total 67,334,048 72,906,986 44,351,928

Restructuring Costs (Tables)

Restructuring Costs (Tables)	12 Months Ended
	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Costs	Restructuring costs included in the Consolidated Statements of Operations and Comprehensive Loss is as follows (in thousands): Year ended, December 31, 2023 Cost of revenue $ 1,138 Selling and marketing 1,832 Research and development 3,375 General and administrative 1,532 Total $ 7,877

Organization and Business Des_2

Organization and Business Description (Details) $ / shares in Units, $ in Thousands				3 Months Ended	12 Months Ended
	Oct. 19, 2023 USD ($) shares	Sep. 23, 2023 shares	Sep. 22, 2023 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) subsidiary	Dec. 31, 2023 USD ($) subsidiary	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Subsidiary, Sale of Stock [Line Items]
Number of wholly-owned subsidiaries | subsidiary				3	3
Underwriting discounts and commissions | $			$ 17,700
Offering-related expenses | $			$ 7,400		$ 25,135	$ 307	$ 270
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Subsidiary, Sale of Stock [Line Items]
Conversion of common stock (in shares)			3,935,793
Increase in prepaid marketing expense | $				$ 92,600
IPO
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)			19,200,000
Issuance price per share (in dollars per share) | $ / shares			$ 30
Aggregate proceeds, net of discounts and commissions | $			$ 320,100
IPO and Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)			11,507,693
IPO and Over-Allotment Option - Shares From Existing Shareholders
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)			7,692,307
Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)	2,764,066
Shares available for purchase (in shares)	2,880,000
Proceeds from sale of stock | $	$ 0
Series A Common Stock | Conversion of Redeemable Common Stock Into Series B Common Stock
Subsidiary, Sale of Stock [Line Items]
Conversion of common stock (in shares)			64,046,223
Series A Common Stock | Common Stock | Conversion of Common Stock Upon Initial Public Offering
Subsidiary, Sale of Stock [Line Items]
Conversion of common stock (in shares)		21,233,074

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) $ / shares in Units, $ in Thousands				12 Months Ended
	Oct. 19, 2023 shares	Sep. 22, 2023 shares	Jul. 28, 2022 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) plan segment $ / shares	Dec. 31, 2022 USD ($) $ / shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of operating segments | segment				1
Number of reportable segments | segment				1
Number of days of advance notice for contract termination for monthly billing cycles				5 days
Number of days of advance notice for contract termination				30 days
Deferred contract acquisition costs, current				$ 15,198	$ 11,215
Deferred contract acquisition costs, non-current				23,177	15,983
Selling and marketing				394,369	213,848	$ 156,342
Accrued expenses				$ 62,838	$ 36,126
Warrants, exercise price (in dollars per share) | $ / shares				$ 0.01	$ 0.01
Issuance of common stock upon exercise of collaboration agreement warrants				$ 62	$ 45
Capitalized prepaid marketing expense				142,300	106,500
Prepaid marketing expense				173,844	84,415
Advertising costs				$ 41,600	40,300	41,900
Number of stock compensation plans | plan				2
Uncertain tax positions				$ 0	0
Accrued interest and penalties related to uncertain tax positions				0	0
Unbilled accounts receivable				1,479	2,253	1,917	$ 125
Cash equivalents				314,500	0
Restricted cash				409	409
Restricted cash, non-current				$ 686	687
Asset retirement obligation, amortization period				5 years
Operating lease, option to extend, renewal term (up to)				5 years
Impairment of long-lived assets				$ 0	$ 0	$ 0
Capitalized internal-use software
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Asset retirement obligation, amortization period				3 years
Total Expenditures Benchmark | Customer One | Customer Concentration Risk
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Customer concentration risk, percentage				19%	19%	25%
Total Expenditures Benchmark | Customer Two | Customer Concentration Risk
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Customer concentration risk, percentage				14%	13%
Total Expenditures Benchmark | Customer Three | Customer Concentration Risk
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Customer concentration risk, percentage				12%
Conversion of Redeemable Common Stock Into Series B Common Stock | Series A Common Stock
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of common stock (in shares) | shares		64,046,223
Unbilled Revenues
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Unbilled accounts receivable				$ 1,800	$ 500
Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred contract acquisition costs, capitalized, amortization period				18 months
Operating lease, term of contract				1 year
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred contract acquisition costs, capitalized, amortization period				60 months
Operating lease, term of contract				8 years
Over-Allotment Option
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Shares issued under purchase agreement (in shares) | shares	2,764,066
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of common stock (in shares) | shares		3,935,793
Shopify | Private Placement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Shares issued under purchase agreement (in shares) | shares			2,951,846
Issuance price per share (in dollars per share) | $ / shares			$ 33.88
Shopify | Investment Option
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance price per share (in dollars per share) | $ / shares			$ 88.93
Additional shares available for purchase (in shares) | shares			15,743,174
Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative arrangement, term			7 years
Collaborative arrangement, renewal term				1 year
Selling and marketing					16,200
Maximum number of common stock shares in which warrants may be converted (in shares) | shares			15,743,174
Warrants, exercise price (in dollars per share) | $ / shares			$ 0.01
Issuance of common stock upon exercise of collaboration agreement warrants			$ 370,300
Marketing expense				$ 52,900	22,000
Prepaid marketing expense				173,800	84,400
Unrecognized marketing expense				$ 295,400
Warrants, cost not yet recognized, period for recognition				5 years 7 months 6 days
Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Class of Warrant or Right, Vesting Period One
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Warrants, vesting percentage		0.25	0.25
Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Class of Warrant or Right, Vesting Periods Two Through Twenty-One
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Warrants, vesting percentage			0.75
Shopify | Revenue Sharing Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative arrangement exceeding threshold, percentage to be shared			0.15
Revenue from collaborative arrangement, threshold			$ 1,000
Selling and marketing				$ 21,900	7,700
Accrued expenses				$ 4,500	2,700
Shopify | Prior Agreement with Shopify
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling and marketing					$ 8,500

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of the period	$ 2,253	$ 1,917	$ 125
Provisions for uncollectible accounts, net of recoveries	28	1,224	1,792
Write offs	(802)	(888)	0
Balance at end of the period	$ 1,479	$ 2,253	$ 1,917

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 738,562	$ 385,820
Restricted cash - current	409	409
Restricted cash - non-current	686	687
Total cash, cash equivalents, and restricted cash	$ 739,657	$ 386,916	$ 327,913	$ 153,621

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Property and Equipment (Details)	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Estimated useful lives of property and equipment	5 years
Office equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of property and equipment	5 years
Computer equipment
Property, Plant and Equipment [Line Items]
Estimated useful lives of property and equipment	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Estimated useful lives of property and equipment	5 years
Capitalized internal-use software
Property, Plant and Equipment [Line Items]
Estimated useful lives of property and equipment	3 years
Asset retirement cost
Property, Plant and Equipment [Line Items]
Estimated useful lives of property and equipment	5 years

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 698,099	$ 472,748	$ 290,640
United States
Disaggregation of Revenue [Line Items]
Revenue	443,471	307,222	197,263
Other Americas
Disaggregation of Revenue [Line Items]
Revenue	38,180	26,790	15,758
APAC
Disaggregation of Revenue [Line Items]
Revenue	72,797	47,905	27,574
EMEA
Disaggregation of Revenue [Line Items]
Revenue	$ 143,651	$ 90,831	$ 50,045

Revenue Recognition - Schedule

Revenue Recognition - Schedule of Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Change in Contract with Customer, Liability, Revenue Recognized [Roll Forward]
Balance at beginning of the period	$ 25,109	$ 15,092
Plus: Billings during the period	713,090	482,765
Less: Revenue recognized during the period	(698,099)	(472,748)
Balance at end of the period	$ 40,100	$ 25,109

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Amounts included in contract liability at the beginning of the period	$ 25.1	$ 15.1
Revenue expected to be recognized	83.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized	$ 79.4
Expected period of recognition	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue expected to be recognized	$ 3.9
Expected period of recognition

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Fair Value, Recurring $ in Thousands	Dec. 31, 2023 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 314,511
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	314,511
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	314,511
Money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	314,511
Money market funds | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0
Money market funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 0

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 71,985	$ 60,938
Less accumulated depreciation and amortization	(28,535)	(15,101)
Property and equipment, net	43,450	45,837
Capitalized internal-use software
Property, Plant and Equipment [Line Items]
Total property and equipment	11,682	4,460
Office equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	3,633	3,203
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	2,939	639
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	7,242	6,683
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	45,768	45,228
Construction-in-progress
Property, Plant and Equipment [Line Items]
Total property and equipment	78	82
Asset retirement cost
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 643	$ 643

Property and Equipment, Net - N

Property and Equipment, Net - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 13.7	$ 8.9	$ 5.3
Capitalized internal-use software development costs	7	2.4
Amortization of capitalized internal-use software development costs	1.8	$ 0.7	$ 0.4
Stock Compensation Plan
Property, Plant and Equipment [Line Items]
Capitalized internal-use software development costs	$ 1.3

Property and Equipment, Net - A

Property and Equipment, Net - Asset Retirement Obligation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 722	$ 685
Additions	0	0
Accretion	39	37
Ending balance	$ 761	$ 722

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued compensation and employee related costs	$ 25,644	$ 16,926
Accrued sabbatical	3,394	0
Accrued value added tax	7,530	4,937
Other accrued taxes	6,830	1,754
Accrued cost of revenue	6,656	7,923
Accrued professional services	3,605	2,297
Accrued marketing	6,374	980
Other accrued expenses	2,805	1,309
Total accrued expenses	$ 62,838	$ 36,126

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Year Ending December 31,
2024	$ 117,668
2025	116,965
2026	70,761
2027	40,833
2028	0
Total Contractual Commitments:	$ 346,227

Leases - Components of Lease Ex

Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease cost	$ 12,618	$ 12,091	$ 10,517
Short-term lease cost	630	121	0
Financing lease cost	21	21	16
Total lease cost	$ 13,269	$ 12,233	$ 10,533

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating lease ROU assets	$ 36,987	$ 45,695
Operating lease liabilities, current	14,081	14,864
Operating lease liabilities, non-current	37,498	47,544
Total lease liabilities	$ 51,579	$ 62,408

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Cash paid for operating lease liabilities, net of tenant incentives received	$ 15,197	$ 9,272	$ 10,824
ROU assets recognized for new leases and amendments (non-cash)	$ 1,299	$ 3,452	$ 6,132

Leases - Other Information (Det

Leases - Other Information (Details)	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Weighted average remaining lease term	4 years 1 month 6 days	5 years
Weighted average discount rate	4.97%	4.96%

Leases - Future Undiscounted An

Leases - Future Undiscounted Annual Cash Flows (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
2024	$ 14,383
2025	13,237
2026	13,429
2027	12,692
2028	3,205
Thereafter	0
Total future undiscounted lease payments	56,946
Less imputed interest	(5,367)
Total lease liabilities	$ 51,579	$ 62,408

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income before Income Tax, Domestic and Foreign (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
United States	$ (312,759)	$ (51,729)	$ (80,260)
Foreign	5,718	2,619	1,186
Loss before income taxes	$ (307,041)	$ (49,110)	$ (79,074)

Income Taxes - Provision (Benef

Income Taxes - Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 0	$ 0	$ 0
State	(26)	99	45
Foreign	4,652	56	179
Current income tax provision	4,626	155	224
Deferred:
Federal	0	(95)	0
State	0	(16)	0
Foreign	(3,434)	39	95
Deferred income tax provision	(3,434)	(72)	95
Provision for income taxes	$ 1,192	$ 83	$ 319

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Contingency [Line Items]
U.S. federal taxes at statutory rate	21%	21%	21%
State taxes, net of federal benefit	4.30%	4.40%	4.80%
Permanent items	(0.40%)	(1.00%)	(0.20%)
Stock-based compensation	1.60%	5.60%	5%
Foreign rate differential	0%	0%	0%
Non-deductible officers compensation	(2.30%)	0%	0%
Prepaid marketing expense	3.60%	0%	0%
Other	0%	(0.80%)	0.10%
Change in valuation allowance	(32.90%)	(47.50%)	(42.20%)
Total	(0.40%)	(0.20%)	(0.40%)
Domestic Tax Authority
Income Tax Contingency [Line Items]
Research and development credits	3.80%	10.30%	7.90%
State and Local Jurisdiction
Income Tax Contingency [Line Items]
Research and development credits	0.90%	7.80%	3.20%

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 88,200	$ 49,093
Research and development credits	36,217	21,829
Stock-based compensation	32,204	1,218
Lease liability	12,933	17,225
Capitalized research and development	63,701	21,728
Other	5,553	2,864
Total deferred tax assets	238,808	113,957
Deferred tax liabilities:
Depreciation	(3,543)	(5,481)
Deferred commissions	(7,657)	(5,451)
Amortization	(2,049)	(85)
ROU asset	(9,303)	(13,202)
Prepaid marketing expense	(43,084)	(20,666)
Total deferred tax liabilities	(65,636)	(44,885)
Valuation allowance	(170,076)	(69,205)
Net deferred tax assets	$ 3,096
Net deferred tax liabilities		$ (133)

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
U.S. federal taxes at statutory rate	21%	21%	21%
Federal net operating loss carryforwards, not subject to expiration	$ 349.2	$ 199.2
State net operating loss carryforwards, subject to expiration	245.1	118.6
Increase in valuation allowance	100.9	23.3
Uncertain tax positions	0	0
Expected material change in uncertain tax benefits	0
Foreign earnings repatriated	0	0
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	25.1	13.6
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Tax credit carryforward	$ 14	$ 10.4

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Foreign Plan
Defined Contribution Plan Disclosure [Line Items]
Employer contributions to plan	$ 1.8	$ 0.8	$ 0.3
UNITED KINGDOM
Defined Contribution Plan Disclosure [Line Items]
Additional percentage of employees wages contributed by employer	5%
AUSTRALIA
Defined Contribution Plan Disclosure [Line Items]
Additional percentage of employees wages contributed by employer	11%
United States
Defined Contribution Plan Disclosure [Line Items]
Employer contributions to plan	$ 7.4	$ 6.6	$ 3.8

Redeemable Common Stock, Comm_3

Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) - Narrative (Details) $ / shares in Units, $ in Thousands				12 Months Ended				36 Months Ended
	Sep. 22, 2023 USD ($) $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Jul. 28, 2022 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) vote $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2019 shares	Dec. 31, 2021 $ / shares shares
Class of Warrant or Right [Line Items]
Redeemable common stock issued (in shares)						3,025,625		64,046,223
Proceeds from issuance of common stock, net of issuance costs | $				$ 0	$ 99,558	$ 345,726
Preferred stock, shares authorized (in shares)		0		100,000,000	0
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.001		$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)		0		0	0
Preferred stock, shares outstanding (in shares)		0		0	0
Warrants, exercise price (in dollars per share) | $ / shares		$ 0.01		$ 0.01	$ 0.01
Warrants vested (in shares)				6,051,285	4,526,161
Restricted common stock, issued (in shares)							142,908
Restricted common stock liability | $		$ 100
Payments of stock issuance costs | $	$ 7,400			$ 25,135	$ 307	$ 270
Automatic conversion of outstanding common stock, period				7 years
Restricted stock outstanding
Class of Warrant or Right [Line Items]
Aggregate fair value of restricted common stock vested | $				$ 700	$ 1,200
Series A Common Stock
Class of Warrant or Right [Line Items]
Common stock, shares authorized (in shares)		0		3,000,000,000	0
Number of votes per common share | vote				1
Series A Common Stock | Conversion of Redeemable Common Stock Into Series B Common Stock
Class of Warrant or Right [Line Items]
Conversion of common stock (in shares)	64,046,223
Series A Common Stock | Common Stock
Class of Warrant or Right [Line Items]
Issuance of common stock, net of issuance costs (in shares)				11,507,693
Series B Common Stock
Class of Warrant or Right [Line Items]
Common stock, shares authorized (in shares)		316,000,000		350,000,000	316,000,000
Number of votes per common share | vote				10
Number of shares convertible (in shares)				1
Series B Common Stock | Common Stock
Class of Warrant or Right [Line Items]
Issuance of common stock, net of issuance costs (in shares)					2,951,846	7,339,392
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Conversion of common stock (in shares)	3,935,793
Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Maximum number of common stock shares in which warrants may be converted (in shares)			15,743,174
Warrants, exercise price (in dollars per share) | $ / shares			$ 0.01
Term of warrants (in years)			10 years
Dividend yield | Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Warrants outstanding, measurement input				0
Contractual term | Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Warrants outstanding, measurement input				10
Volatility | Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Warrants outstanding, measurement input				0.5500
Risk-free rate | Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Warrants outstanding, measurement input				0.0285
Class of Warrant or Right, Vesting Period One | Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Warrants, vesting percentage	0.25		0.25
Class of Warrant or Right, Vesting Periods Two Through Twenty-One | Shopify | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Class of Warrant or Right [Line Items]
Warrants, vesting percentage			0.75
Public Stock Offering
Class of Warrant or Right [Line Items]
Redeemable common stock issued (in shares)						3,025,625
Shares issued under purchase agreement (in shares)						10,365,017
Issuance price per share (in dollars per share) | $ / shares						$ 33.38		$ 33.38
Proceeds from issuance of common stock, net of issuance costs | $						$ 346,000
Public Stock Offering | Series B Common Stock
Class of Warrant or Right [Line Items]
Issuance of common stock, net of issuance costs (in shares)						7,339,392
IPO
Class of Warrant or Right [Line Items]
Shares issued under purchase agreement (in shares)	19,200,000
Issuance price per share (in dollars per share) | $ / shares	$ 30
Private Placement | Shopify
Class of Warrant or Right [Line Items]
Shares issued under purchase agreement (in shares)			2,951,846
Issuance price per share (in dollars per share) | $ / shares			$ 33.88
Common Stock and Investment Option
Class of Warrant or Right [Line Items]
Proceeds from sale of stock | $			$ 100,000
Payments of stock issuance costs | $			400
Investment Option
Class of Warrant or Right [Line Items]
Gross proceeds from issuance of common stock | $			$ 30,600
Investment Option | Shopify
Class of Warrant or Right [Line Items]
Issuance price per share (in dollars per share) | $ / shares			$ 88.93
Additional shares available for purchase (in shares)			15,743,174
Common Stock
Class of Warrant or Right [Line Items]
Gross proceeds from issuance of common stock | $			$ 69,400

Redeemable Common Stock, Comm_4

Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) - Schedule of Warrant Activity (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Shares
Outstanding, beginning (in shares)	11,217,017
Granted (in shares)	0
Exercised (in shares)	(6,051,285)
Cancelled (in shares)	0
Outstanding, ending (in shares)	5,165,732
Weighted Average Exercise Price
Outstanding, beginning (in dollars per share) | $ / shares	$ 0.01
Exercised (in dollars per share) | $ / shares	0.01
Outstanding, ending (in dollars per share) | $ / shares	$ 0.01
Weighted Average Remaining Life (years)
Warrants outstanding, beginning	9 years 6 months 25 days
Exercised	8 years 11 months 12 days
Warrants outstanding, ending	8 years 6 months 29 days

Redeemable Common Stock, Comm_5

Redeemable Common Stock, Common Stock, and Stockholders' Equity (Deficit) - Schedule of Restricted Common Stock Activity (Details) - Restricted stock outstanding	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Shares
Unvested and outstanding, beginning balance (in shares)	26,795
Granted ( in shares)	0
Vested (in shares)	(26,795)
Unvested and outstanding, ending balance (in shares)	0
Weighted Average Grant Date Fair Value
Unvested and outstanding, beginning balance (in dollars per share) | $ / shares	$ 2.84
Vested (in dollars per share) | $ / shares	2.84
Unvested and outstanding, ending balance (in dollars per share) | $ / shares	$ 0

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) $ in Thousands			12 Months Ended
	Apr. 10, 2023 grantee shares	Mar. 15, 2023 employee shares	Dec. 31, 2023 USD ($) employee shares	Dec. 31, 2022 USD ($) employee shares	Dec. 31, 2021 USD ($) employee shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Options granted (in shares) | shares			0	0	0
Options exercised, aggregate intrinsic value			$ 54,700	$ 53,200	$ 169,700
Reduction of full time workforce, percentage		8%
Reduction of full time workforce, number of employees | employee		130
General and administrative expense				1,500
Prorated stock-based compensation expense				$ 3,800	$ 1,100
Shares purchased by secondary investors (in shares) | shares			912,187	1,002,968	4,262,974
Share-based compensation expense recognized			$ 340,799	$ 8,302	$ 51,989
Capitalized stock-based compensation expense			1,349	0	2
Cash paid in exchange for restricted stock unit cancellation				1,500
Cash paid for repurchase and retirement of common stock					16,700
Unrecognized share-based compensation cost, options			100
Selling and marketing
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense recognized			107,954	985	29,713
Cash paid for repurchase and retirement of common stock					8,800
Research and development
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Cash paid for repurchase and retirement of common stock					5,800
General and administrative
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense recognized			87,688	$ 5,958	13,123
Cash paid for repurchase and retirement of common stock					2,100
Share-Based Payment Arrangement, Nonemployee
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation modifications, number of employees affected | employee				1
Secondary Market Sale By Employees To Investors
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation expense recognized			$ 0	$ 800	$ 21,500
2015 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Incentive stock options, exercise price, fair value threshold for employees holding 10% or more of voting stock			1.10
2023 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares authorized for issuance (in shares) | shares			44,981,488
Number of shares available for grant (in shares) | shares			40,775,315
Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expiration period			10 years
Award vesting period			4 years
Stock-based compensation modifications, number of employees affected | employee			4	3	3
Stock-based compensation modifications, number of shares affected (in shares) | shares			1,004,667		1,326,461
Incremental stock-based compensation expense from modifications					$ 9,900
Unrecognized share-based compensation cost, period of recognition			4 months 24 days
Options | Share-Based Payment Arrangement, Nonemployee
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation modifications, number of shares affected (in shares) | shares		608,698		2,616
Incremental stock-based compensation expense from modifications				$ 100
Options | Share-Based Payment Arrangement, Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting, percentage			25%
Award vesting period			12 months
Options | Share-Based Payment Arrangement, Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting, percentage			75%
Award vesting period			3 years
Options, modification, extension
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation modifications, number of employees affected | employee				2
Stock-based compensation modifications, number of shares affected (in shares) | shares				65,704
Incremental stock-based compensation expense from modifications			$ 800
Options, modification, restructure
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Incremental stock-based compensation expense from modifications			$ 600
Restricted Stock Units
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Requisite service period			4 years
Award vesting period			4 years
Fair value of restricted stock units vested			$ 214,700	$ 1,300	$ 500
Stock-based compensation modifications, number of employees affected	657		2
Stock-based compensation modifications, number of shares affected (in shares) | shares	4,250,947			177,684
Number of shares cancelled (in shares) | shares				63,775
Unrecognized share-based compensation cost			$ 257,500
Unrecognized share-based compensation cost, period of recognition			3 years 3 months 18 days
Restricted Stock Units | Share-Based Payment Arrangement, Employee
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation modifications, number of shares affected (in shares) | shares			167,500
Restricted Stock Units | Share-Based Payment Arrangement, Nonemployee
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation modifications, number of shares affected (in shares) | shares		64,301		154
Restricted Stock Units | Share-Based Payment Arrangement, Tranche One
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting, percentage			25%
Award vesting period			1 year
Restricted Stock Units | Share-Based Payment Arrangement, Tranche Two
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Award vesting period			3 years
Restricted Stock Units, modification, accelerated vesting
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation modifications, number of employees affected | employee				2
Stock-based compensation modifications, number of shares affected (in shares) | shares				22,029

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Number of Options
Options outstanding, beginning balance (in shares)	34,207,554
Exercised (in shares)	(2,419,308)
Forfeited and expired (in shares)	(53,521)
Options outstanding, ending balance (in shares)	31,734,725	34,207,554
Weighted Average Exercise Price (Per Share)
Options outstanding, beginning balance (in dollars per share)	$ 0.61
Exercised (in dollars per share)	1.56
Forfeited and expired (in dollars per share)	3.22
Options outstanding, ending balance (in dollars per share)	$ 0.54	$ 0.61
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding, weighted average remaining contractual life	2 years 7 months 24 days	3 years 8 months 26 days
Options outstanding, aggregate intrinsic value	$ 864,605	$ 781,247
Options exercisable (in shares)	31,639,454
Options exercisable, weighted average exercise price (in dollars per share)	$ 0.53
Options exercisable, weighted average remaining contractual life	2 years 7 months 20 days
Options exercisable, aggregate intrinsic value	$ 862,297
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest [Abstract]
Options expected to vest (in shares)	31,734,725
Options expected to vest, weighted average exercise price (in dollars per share)	$ 0.54
Options expected to vest, weighted average remaining contractual life	2 years 7 months 24 days
Options expected to vest, aggregate intrinsic value	$ 864,605

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Restricted Stock Unit Activity (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Number of Shares
Unvested and outstanding, beginning balance (in shares) | shares	11,712,446
Granted ( in shares) | shares	11,896,929
Vested (in shares) | shares	(7,206,386)
Forfeited (in shares) | shares	(1,712,572)
Unvested and outstanding, ending balance (in shares) | shares	14,690,417
Weighted Average Grant Date Fair Value
Unvested and outstanding, beginning balance (in dollars per share) | $ / shares	$ 30.24
Granted (in dollars per share) | $ / shares	26.23
Vested (in dollars per share) | $ / shares	29.49
Forfeited (in dollars per share) | $ / shares	29.51
Unvested and outstanding, ending balance (in dollars per share) | $ / shares	$ 27.44

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation, net of amounts capitalized	$ 340,799	$ 8,302	$ 51,989
Capitalized stock-based compensation expense	1,349	0	2
Total stock-based compensation expense	342,148	8,302	51,991
Cost of revenue
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation, net of amounts capitalized	24,973	129	960
Selling and marketing
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation, net of amounts capitalized	107,954	985	29,713
Research and development
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation, net of amounts capitalized	120,184	1,230	8,193
General and administrative
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock-based compensation, net of amounts capitalized	$ 87,688	$ 5,958	$ 13,123

Loss Per Share - Schedule of Ea

Loss Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss	$ (308,233)	$ (49,193)	$ (79,393)
Denominator:
Weighted-average shares - basic (in shares)	242,889,272	229,857,206	220,865,179
Weighted average shares - diluted (in shares)	242,889,272	229,857,206	220,865,179
Net loss per share attributable to Series A and Series B common Stockholders, basic (in dollars per share)	$ (1.27)	$ (0.21)	$ (0.36)
Net loss per share attributable to Series A and Series B common Stockholders, diluted (in dollars per share)	$ (1.27)	$ (0.21)	$ (0.36)

Loss Per Share - Schedule of Po

Loss Per Share - Schedule of Potential Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	67,334,048	72,906,986	44,351,928
Warrants outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	5,165,732	11,217,017	0
Investment Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	15,743,174	15,743,174	0
RSUs outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	14,690,417	11,712,446	7,430,700
Options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	31,734,725	34,207,554	36,858,706
Restricted stock outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	26,795	62,522

Restructuring Costs - Narrative

Restructuring Costs - Narrative (Details) - USD ($) $ in Millions	Mar. 15, 2023	Dec. 31, 2023
Restructuring and Related Activities [Abstract]
Reduction of full time workforce, percentage	8%
Unpaid restructuring costs		$ 0

Restructuring Costs - Schedule

Restructuring Costs - Schedule of Restructuring Costs (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 7,877
Cost of revenue
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,138
Selling and marketing
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,832
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	3,375
General and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,532