Outbrain (OB) 10-Q 12 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 01, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-40643
Entity Registrant Name	Outbrain Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5391629
Entity Address, Address Line One	111 West 19th Street,
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10011
City Area Code	(646)
Local Phone Number	859-8594
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	OB
Security Exchange Name	NASDAQ
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		55,507,975
Entity Central Index Key	0001454938
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 482,447	$ 93,641
Accounts receivable, net of allowances	161,325	165,449
Prepaid expenses and other current assets	27,734	18,326
Total current assets	671,506	277,416
Property, equipment and capitalized software, net	24,782	24,756
Intangible assets, net	6,704	9,812
Goodwill	32,881	32,881
Other assets	11,471	11,621
TOTAL ASSETS	747,344	356,486
CURRENT LIABILITIES:
Accounts payable	139,208	118,491
Accrued compensation and benefits	22,081	23,000
Accrued and other current liabilities	104,066	109,747
Deferred revenue	5,462	5,512
Total current liabilities	270,817	256,750
Long-term debt	236,000	0
Other liabilities	15,963	17,105
TOTAL LIABILITIES	522,780	273,855
Commitments and contingencies (Note 8)
Convertible preferred stock, par value of $0.001 per share — 100,000,000 shares authorized and no shares outstanding as of September 30, 2021, and 27,766,563 shares authorized and 27,652,449 of Series A, B, C, D, E, F, G and H outstanding as of December 31, 2020.	0	162,444
STOCKHOLDERS’ EQUITY (DEFICIT):
Common stock, par value of $0.001 per share — 1,000,000,000 shares authorized and 55,467,215 shares issued and outstanding as of September 30, 2021, and 65,183,785 shares authorized and 17,158,802 shares issued and outstanding as of December 31, 2020.	55	17
Additional paid-in capital	426,030	92,705
Accumulated other comprehensive loss	(5,317)	(4,290)
Accumulated deficit	(196,204)	(168,245)
TOTAL STOCKHOLDERS’ EQUITY (DEFICIT)	224,564	(79,813)
TOTAL LIABILITIES, CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT)	$ 747,344	$ 356,486

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Convertible preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	100,000,000	27,766,563
Convertible preferred stock, shares outstanding	0	27,652,449
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized	1,000,000,000	65,183,785
Common stock, shares issued	55,467,215	17,158,802
Common stock, shares outstanding	55,467,215	17,158,802

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Revenue	$ 250,784	$ 186,510	$ 725,961	$ 521,704
Traffic acquisition costs	182,669	137,866	530,606	392,812
Other cost of revenue	7,846	6,771	22,555	22,292
Total cost of revenue	190,515	144,637	553,161	415,104
Gross profit	60,269	41,873	172,800	106,600
Operating expenses:
Research and development	10,659	6,867	27,561	20,752
Sales and marketing	26,047	17,476	67,101	55,587
General and administrative	29,979	13,909	52,619	35,858
Total operating expenses	66,685	38,252	147,281	112,197
(Loss) income from operations	(6,416)	3,621	25,519	(5,597)
Other (expense) income, net:
Charges related to exchange of senior notes upon IPO	(42,049)	0	(42,049)	0
Interest expense	(1,656)	(196)	(2,015)	(627)
Interest income and other income (expense), net	1,218	(878)	(1,978)	(322)
Total other (expense) income, net	(42,487)	(1,074)	(46,042)	(949)
(Loss) income before provision for income taxes	(48,903)	2,547	(20,523)	(6,546)
Provision for income taxes	5,003	6	7,436	3,106
Net (loss) income	$ (53,906)	$ 2,541	$ (27,959)	$ (9,652)
Weighted average shares outstanding:
Basic (in shares)	47,859,056	16,846,853	27,645,471	16,747,054
Diluted (in shares)	47,859,056	19,460,110	27,645,471	16,747,054
Net (loss) income per common share:
Basic (in usd per share)	$ (1.13)	$ 0.06	$ (1.01)	$ (0.58)
Diluted (in usd per share)	$ (1.13)	$ 0.05	$ (1.01)	$ (0.58)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (53,906)	$ 2,541	$ (27,959)	$ (9,652)
Other comprehensive (loss) income:
Foreign currency translation adjustments	(1,187)	1,006	(1,027)	(676)
Comprehensive (loss) income	$ (55,093)	$ 3,547	$ (28,986)	$ (10,328)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Convertible Preferred Stock, Balance - beginning of period (in shares) at Dec. 31, 2019	27,652,449
Convertible Preferred Stock, Balance - beginning of period at Dec. 31, 2019	$ 162,444
Convertible Preferred Stock, Balance - end of period (in shares) at Sep. 30, 2020	27,652,449
Convertible Preferred Stock, Balance - end of period at Sep. 30, 2020	$ 162,444
Balance - beginning of period (in shares) at Dec. 31, 2019		16,584,315
Balance - beginning of period at Dec. 31, 2019	(89,662)	$ 17	$ 88,446	$ (5,523)	$ (172,602)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of employee stock options (in shares)		105,785
Issuance of common stock upon exercise of employee stock options and warrants	475		475
Issuance of common stock upon vesting of restricted stock units (in shares)		222,451
Stock-based compensation	2,759		2,759
Other comprehensive income (loss)	(676)			(676)
Net (loss) income	(9,652)				(9,652)
Other	(6)				(6)
Balance - end of period (in shares) at Sep. 30, 2020		16,912,551
Balance - end of period at Sep. 30, 2020	$ (96,762)	$ 17	91,680	(6,199)	(182,260)
Convertible Preferred Stock, Balance - beginning of period (in shares) at Jun. 30, 2020	27,652,449
Convertible Preferred Stock, Balance - beginning of period at Jun. 30, 2020	$ 162,444
Convertible Preferred Stock, Balance - end of period (in shares) at Sep. 30, 2020	27,652,449
Convertible Preferred Stock, Balance - end of period at Sep. 30, 2020	$ 162,444
Balance - beginning of period (in shares) at Jun. 30, 2020		16,832,815
Balance - beginning of period at Jun. 30, 2020	(101,272)	$ 17	90,717	(7,205)	(184,801)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of employee stock options (in shares)		5,260
Issuance of common stock upon exercise of employee stock options and warrants	37		37
Issuance of common stock upon vesting of restricted stock units (in shares)		74,476
Stock-based compensation	926		926
Other comprehensive income (loss)	1,006			1,006
Net (loss) income	2,541				2,541
Balance - end of period (in shares) at Sep. 30, 2020		16,912,551
Balance - end of period at Sep. 30, 2020	$ (96,762)	$ 17	91,680	(6,199)	(182,260)
Convertible Preferred Stock, Balance - beginning of period (in shares) at Dec. 31, 2020	27,652,449
Convertible Preferred Stock, Balance - beginning of period at Dec. 31, 2020	$ 162,444
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock to common stock (in shares)	(27,652,449)
Conversion of convertible preferred stock to common stock	$ (162,444)
Convertible Preferred Stock, Balance - end of period (in shares) at Sep. 30, 2021	0
Convertible Preferred Stock, Balance - end of period at Sep. 30, 2021	$ 0
Balance - beginning of period (in shares) at Dec. 31, 2020	17,158,802	17,158,802
Balance - beginning of period at Dec. 31, 2020	$ (79,813)	$ 17	92,705	(4,290)	(168,245)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of convertible preferred stock to common stock (in shares)		28,091,267
Conversion of convertible preferred stock to common stock	162,444	$ 28	162,416
Issuance of common stock from initial public offering, net of issuance costs (in shares)		8,000,000
Issuance of common stock from initial public offering, net of issuance costs	$ 145,105	$ 8	145,097
Issuance of common stock upon exercise of employee stock options (in shares)	1,636,996	1,824,770
Issuance of common stock upon exercise of employee stock options and warrants	$ 4,327	$ 2	4,325
Issuance of common stock upon vesting of restricted stock units (in shares)		392,376
Stock-based compensation	21,487		21,487
Other comprehensive income (loss)	(1,027)			(1,027)
Net (loss) income	$ (27,959)				(27,959)
Balance - end of period (in shares) at Sep. 30, 2021	55,467,215	55,467,215
Balance - end of period at Sep. 30, 2021	$ 224,564	$ 55	426,030	(5,317)	(196,204)
Convertible Preferred Stock, Balance - beginning of period (in shares) at Jun. 30, 2021	27,652,449
Convertible Preferred Stock, Balance - beginning of period at Jun. 30, 2021	$ 162,444
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock to common stock (in shares)	(27,652,449)
Conversion of convertible preferred stock to common stock	$ (162,444)
Convertible Preferred Stock, Balance - end of period (in shares) at Sep. 30, 2021	0
Convertible Preferred Stock, Balance - end of period at Sep. 30, 2021	$ 0
Balance - beginning of period (in shares) at Jun. 30, 2021		17,764,264
Balance - beginning of period at Jun. 30, 2021	(49,133)	$ 18	97,277	(4,130)	(142,298)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of convertible preferred stock to common stock (in shares)		28,091,267
Conversion of convertible preferred stock to common stock	162,444	$ 28	162,416
Issuance of common stock from initial public offering, net of issuance costs (in shares)		8,000,000
Issuance of common stock from initial public offering, net of issuance costs	145,105	$ 8	145,097
Issuance of common stock upon exercise of employee stock options (in shares)		1,428,879
Issuance of common stock upon exercise of employee stock options and warrants	2,793	$ 1	2,792
Issuance of common stock upon vesting of restricted stock units (in shares)		182,805
Stock-based compensation	18,448		18,448
Other comprehensive income (loss)	(1,187)			(1,187)
Net (loss) income	$ (53,906)				(53,906)
Balance - end of period (in shares) at Sep. 30, 2021	55,467,215	55,467,215
Balance - end of period at Sep. 30, 2021	$ 224,564	$ 55	$ 426,030	$ (5,317)	$ (196,204)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (27,959)	$ (9,652)
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Charges related to exchange of senior notes upon IPO	42,049	0
Depreciation and amortization of property and equipment	5,068	5,094
Amortization of capitalized software development costs	6,241	5,555
Amortization of intangible assets	2,687	3,404
Loss (gain) on sale of assets	3	(1,111)
Stock-based compensation	21,396	2,732
Provision for doubtful accounts	2,190	1,325
Deferred income taxes	(918)	(418)
Other	1,999	(1,406)
Changes in operating assets and liabilities:
Accounts receivable	602	18,600
Prepaid expenses and other current assets	(10,386)	(1,735)
Other assets	(191)	(1,484)
Accounts payable	21,230	15,116
Accrued and other current liabilities	(3,714)	5,835
Deferred revenue	31	887
Other	749	783
Net cash provided by operating activities	61,077	43,525
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(3,885)	(1,268)
Capitalized software development costs	(7,434)	(6,686)
Proceeds from sale of assets	0	1,117
Other	(41)	(31)
Net cash used in investing activities	(11,360)	(6,868)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from IPO issuance of common stock, net of underwriting costs	148,800	0
Payment of initial public offering transaction costs	(3,695)	0
Proceeds from issuance of debt	200,000	0
Payment of deferred financing costs	(6,067)	0
Proceeds from borrowings on revolving credit facility	0	10,000
Principal repayments on revolving credit facility	0	(10,000)
Proceeds from exercise of stock options and warrants	4,327	442
Principal payments on capital obligation arrangements	(3,322)	(3,689)
Net cash provided by (used in) financing activities	340,043	(3,247)
Effect of exchange rate changes	(978)	868
Net increase in cash, cash equivalents and restricted cash	388,782	34,278
Cash, cash equivalents and restricted cash — Beginning	94,067	49,982
Cash, cash equivalents and restricted cash — Ending	482,849	84,260
RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH TO THE CONDENSED CONSOLIDATED BALANCE SHEETS
Cash and cash equivalents	482,447	83,854
Restricted cash, included in other assets	402	406
Total cash, cash equivalents, and restricted cash	$ 482,849	$ 84,260

Organization, Description of Bu

Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements	Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements Organization and Description of Business Outbrain Inc., together with our subsidiaries, (“Outbrain”, the “Company”, “we”, “our” or “us”) was incorporated in August 2006 in Delaware. The Company is headquartered in New York, New York and has wholly-owned subsidiaries in Israel, Europe, Asia, Brazil and Australia. Outbrain is a leading recommendation platform powering the open web. Our platform provides personalized recommendations that appear as links to content, advertisements and videos on media owners’ online properties. We generate revenue from marketers through user engagements with promoted recommendations that we deliver across a variety of third-party media owners’ properties. We pay traffic acquisition costs to our media owner partners on whose digital properties the recommendations are shown. Our advertiser solutions are mainly priced using a performance-based model based on the actual number of engagements generated by users, which is highly dependent on our ability to generate trustworthy and interesting recommendations to individual users based on our proprietary algorithms. A small portion of our revenue is generated through advertisers participating in programmatic auctions wherein the pricing is determined by the auction results and not dependent on user engagement. Initial Public Offering On July 22, 2021, the Company’s Form S-1, filed on June 29, 2021, as amended, was declared effective by the U.S. Securities and Exchange Commission (the “SEC”) in connection with the Company’s initial public offering (“IPO”) of the Company’s common stock and its common stock began trading on The Nasdaq Stock Market LLC (“Nasdaq”) on July 23, 2021. On July 27, 2021, the Company closed its IPO and issued 8,000,000 shares of its common stock at an initial offering price of $20.00 per share, receiving aggregate net proceeds of $145.1 million, after deducting underwriting discounts, commissions and other offering costs. Deferred offering costs of $3.7 million primarily consisted of accounting, legal and other transaction costs directly related to the IPO. Prior to the IPO, deferred offering costs were recorded within prepaid expenses and other current assets on the Company’s consolidated balance sheet. Upon the Company’s IPO, such costs were reclassified to additional paid-in capital within stockholders’ equity (deficit) and recorded against the proceeds of the offering. In connection with the IPO, all of the shares of the Company’s convertible preferred stock outstanding automatically converted into an aggregate of 28,091,267 shares of the Company’s common stock, with all series converted on a one-to-one basis, with the exception of Series F, which was converted at 1.14-to-1, based on the terms of the Series F agreement and the IPO price. The total carrying value of convertible preferred stock of $162.4 million was reclassified to stockholders’ equity (deficit). Shares Authorization In July 2021, the Company’s certificate of incorporation was amended and restated to provide the Company with the authority to issue up to 1.1 billion shares, comprised of 1.0 billion shares of $0.001 par value common stock and 0.1 billion shares of $0.001 par value preferred stock. Each holder of common stock is entitled to one vote with respect to each share of common stock and is entitled to dividends, if and when declared by the Company’s Board of Directors (the “Board”), subject to preferential rights of preferred stockholders. Basis of Presentation The accompanying condensed consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and are unaudited. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes for the year ended December 31, 2020, included with the Company’s final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on July 23, 2021. In July 2021, the Company’s Board and stockholders approved a 1-for-1.7 reverse stock split of its common and convertible preferred stock. The reverse stock split became effective on July 13, 2021. The par value of the common stock was not adjusted as a result of the reverse stock split. In addition, adjustments corresponding to the reverse stock split were made to the ratio at which the convertible preferred stock converted into common stock immediately prior to the closing of the IPO, in accordance with existing terms of the convertible preferred stock. All share and per-share amounts for all periods presented in these financial statements and notes thereto have been adjusted retroactively to reflect the effect of the reverse stock split for all periods presented. Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and related disclosures as of the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. We base our estimates and judgments on historical information and on various other assumptions that we believe are reasonable under the circumstances. Estimates and assumptions made in the accompanying condensed consolidated financial statements include, but are not limited to, the allowance for doubtful accounts, sales allowance, software development costs eligible for capitalization, valuation of deferred tax assets, the useful lives of property and equipment, the useful lives and fair value of intangible assets and goodwill, the fair value of stock-based awards, the recognition and measurement of income tax uncertainties and other contingencies. Actual results could differ materially from these estimates. Certain Risks and Concentrations Financial instruments that potentially subject us to concentrations of credit risk consist of cash and cash equivalents, restricted cash and accounts receivable. Our cash and cash equivalents and restricted cash are generally invested in high-credit quality financial instruments with both banks and financial institutions to reduce the amount of exposure to any single financial institution. We generally do not require collateral to secure accounts receivable. No single marketer accounted for 10% or more of our total revenue for the three months and nine months ended September 30, 2021 or September 30, 2020, or for 10% or more of our gross accounts receivable balance as of September 30, 2021 or December 31, 2020. Two media owners each individually accounted for approximately 10% of our total traffic acquisition costs for the three months ended September 30, 2021, and individually accounted for approximately 10% and 11% of our total traffic acquisition costs for the nine months ended September 30, 2021. For the three months ended September 30, 2020, one media owner individually accounted for 13% of our total traffic acquisition costs, and two accounted for 11% and 13% of our total traffic acquisition costs for the nine months ended September 30, 2020. Segment Information We have a single operating and reporting segment. Our chief operating decision maker is our Co-Chief Executive Officer who makes resource allocation decisions and assesses performance based on financial information presented on a consolidated basis. Recently Adopted and Recently Issued Accounting Pronouncements Under the JOBS Act, the Company meets the definition of an emerging growth company and 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 Company is no longer an emerging growth company or until the Company affirmatively and irrevocably opts out of the extended transition period. Recently adopted accounting pronouncements On January 1, 2021, we early adopted Accounting Standards Update (“ASU”) 2020-06, “Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity,” which simplified the accounting for convertible debt instruments by reducing the number of accounting models used to allocate proceeds from five to three, removing certain conditions for equity classification and amending earnings per share calculations to assume share settlement and to require the if-converted method to be applied to all convertible debt instruments. The adoption of this standard did not have an impact on our consolidated financial statements as of the date of adoption. The Company applied this guidance to its Convertible Notes issued in July 2021 (See Note 6 for additional information). Recently issued accounting pronouncements not yet adopted In February 2016, the Financial Accounting Standards Board (the “FASB”) issued ASU 2016-02, “Leases (Topic 842)”, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than twelve months, regardless of their classification. Leases with a term of twelve months or less will be accounted for similar to existing guidance for operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. ASU 2016-02 supersedes the previous leases standard, Leases (Topic 840). In June 2020 the FASB issued ASU 2020-05 Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities. The amendments in this update defer the effective date of ASU 2016-02 for private companies to fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. Early application is permitted. The Company plans to adopt this standard on January 1, 2022, as required. The Company has aggregated all of its lease agreements and is in the process of analyzing its lease portfolio and assessing the impacts of adoption on its consolidated financial statements. The Company expects its assets and liabilities to increase in connection with the recording of right-of-use assets and lease liabilities upon adoption of this standard. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326),” which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model which requires consideration of forward-looking information to calculate credit loss estimates. These changes will result in an earlier recognition of credit losses. The Company's financial assets held at amortized cost include accounts receivable. The amendments in ASU 2020-05 deferred the effective date for Topic 326 to fiscal years beginning after December 15, 2022. The Company plans to adopt this standard on the earlier of January 1, 2023 or on losing its emerging growth company status. The Company does not expect the adoption of this standard will have a material impact on the consolidated financial statements or related disclosures. See Note 1 to the Company’s audited consolidated financial statements for the year ended December 31, 2020 in our final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on July 23, 2021 for a complete disclosure of the Company’s significant accounting policies.

Revenue Recognition

Revenue Recognition	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition The following table presents total revenue based on where our marketers are physically located: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (In thousands) (In thousands) USA $ 94,599 $ 73,666 $ 265,677 $ 201,447 Europe, the Middle East and Africa (EMEA) 125,102 93,719 377,680 263,543 Other 31,083 19,125 82,604 56,714 Total revenue $ 250,784 $ 186,510 $ 725,961 $ 521,704 Contract Balances

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: • Level I – Valuations based on quoted prices in active markets for identical assets and liabilities; • Level II – Valuations based on quoted prices for similar assets or liabilities in active markets or quoted prices for identical assets or liabilities in inactive markets, inputs that are observable or can be principally corroborated by observable market data; and • Level III – Valuations based on unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities The following table sets forth the fair value of our financial assets measured on a recurring basis by level within the fair value hierarchy: September 30, 2021 Level I Level II Level III Total (In thousands) Financial Assets: Restricted time deposit (1) $ — $ 402 $ — $ 402 Severance pay fund deposits (1) $ — $ 5,315 $ — $ 5,315 Foreign currency forward contract (2) $ — $ 77 $ — $ 77 Total financial assets $ — $ 5,794 $ — $ 5,794 December 31, 2020 Level I Level II Level III Total (In thousands) Financial Assets: Restricted time deposit (1) $ — $ 426 $ — $ 426 Severance pay fund deposits (1) $ — $ 5,379 $ — $ 5,379 Foreign currency forward contract (2) $ — $ 553 $ — $ 553 Total financial assets $ — $ 6,358 $ — $ 6,358 _____________________ (1) Recorded within other assets (2) Recorded within prepaid expenses and other current assets The Company’s 2.95% Convertible Senior Notes due 2026 (“Convertible Notes”) are recorded within long-term debt in its condensed consolidated balance sheet at their carrying value, which may differ from their fair value. The fair value of Convertible Notes is estimated using external pricing data, including any available market data for other debt instruments with similar characteristics. The following table summarizes the carrying value and the estimated fair value of the Company’s Convertible Notes, based on Level II measurements of the fair value hierarchy: September 30, December 31, Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (In thousands) Convertible Notes $ 236,000 $ 240,531 $ — $ —

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Accounts Receivable, Net of Allowances Accounts receivable, net of allowances consists of the following: September 30, December 31, (In thousands) Accounts receivable $ 165,844 $ 169,623 Allowance for doubtful accounts (4,519) (4,174) Accounts receivable, net of allowances $ 161,325 $ 165,449 Allowance for Doubtful Accounts The allowance for doubtful accounts consists of the following activity: Nine Months Ended September 30, 2021 Year Ended December 31, 2020 (In thousands) Allowance for doubtful accounts, beginning balance $ 4,174 $ 3,281 Provision for doubtful accounts, net of recoveries 2,155 2,668 Write-offs (1,810) (1,775) Allowance for doubtful accounts, ending balance $ 4,519 $ 4,174 Property, Equipment and Capitalized Software, Net Property, equipment and capitalized software, net consists of the following: September 30, December 31, 2020 (In thousands) Computer equipment $ 38,354 $ 41,735 Capitalized software development costs 51,295 43,728 Software 2,947 3,444 Leasehold improvements 1,245 2,805 Furniture and fixtures 252 908 Property, equipment and capitalized software, gross 94,093 92,620 Less: accumulated depreciation and amortization (69,311) (67,864) Total property, equipment and capitalized software, net $ 24,782 $ 24,756 Current Liabilities At September 30, 2021 and December 31, 2020, accrued and other current liabilities of $104.1 million and $109.7 million, respectively, included accrued traffic acquisition costs of $64.4 million and $77.2 million, respectively. In addition, accounts payable included $129.8 million and $111.7 million of traffic acquisition costs as of September 30, 2021 and December 31, 2020, respectively.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The Company’s goodwill balance was $32.9 million as of September 30, 2021 and December 31, 2020 and the Company has not recorded any accumulated impairments of goodwill. The gross carrying amount and accumulated amortization of our intangible assets are as follows: As of September 30, 2021 Amortization Gross Value Accumulated Net Carrying (In thousands) Developed technology 36-48 months $ 8,425 $ (8,425) $ — Customer relationships 48 months 5,445 (3,853) 1,592 Publisher relationships 48 months 8,606 (5,379) 3,227 Trade names 8 years 1,705 (533) 1,172 Other 14 years 870 (157) 713 Total intangible assets, net $ 25,051 $ (18,347) $ 6,704 As of December 31, 2020 Amortization Gross Value Accumulated Net Carrying (In thousands) Developed technology 36-48 months $ 8,425 $ (8,388) $ 37 Customer relationships 48 months 5,694 (3,166) 2,528 Publisher relationships 48 months 9,111 (3,986) 5,125 Trade names 8 years 1,805 (395) 1,410 Other 14 years 830 (118) 712 Total intangible assets, net $ 25,865 $ (16,053) $ 9,812 No impairment charges were recorded during the three months and nine months ended September 30, 2021 and September 30, 2020. As of September 30, 2021, estimated amortization related to our identifiable acquisition-related intangible assets in future periods was as follows: Year Amount (In thousands) Remainder of 2021 $ 870 2022 3,479 2023 1,069 2024 266 2025 266 Thereafter 754 Total $ 6,704

Long Term Debt

Long Term Debt	9 Months Ended
	Sep. 30, 2021
Debt Disclosure [Abstract]
Long Term Debt	Long-Term Debt Convertible Notes On July 1, 2021, the Company completed the sale of $200 million aggregate principal amount of senior subordinated secured notes due July 1, 2026 (the “Notes”), in a private placement to institutional investors affiliated with the funds managed by The Baupost Group, L.L.C. (the “Baupost Investors”), pursuant to a Senior Subordinated Secured Note Purchase Agreement dated July 1, 2021 (the “Note Purchase Agreement”). Upon issuance of the Notes, the Company recorded a $36.0 million discount in connection with the embedded conversion feature, as well as deferred financing costs of $6.0 million in its consolidated balance sheet. The Notes, which were exchanged and cancelled upon the IPO, bore interest that accrued at the rate of (i) prior to July 1, 2024, 10.0% per annum and (ii) on and after July 1, 2024, 14.5% per annum, payable quarterly and were guaranteed by certain of the Company’s wholly-owned subsidiaries and secured by a second priority lien on all of the Company’s and its subsidiaries’ tangible and intangible assets, subject to certain excluded assets, permitted liens and customary exceptions. On July 27, 2021, in connection with the closing of the Company’s IPO and pursuant to the terms of the Note Purchase Agreement, the Company exchanged $200 million aggregate principal amount of the Notes due July 1, 2026 for $236 million aggregate principal amount of the Company’s 2.95% Convertible Senior Notes due 2026 (the “Convertible Notes”), pursuant to an indenture, dated as of July 27, 2021 (the “Indenture”), between the Company and The Bank of New York Mellon, as trustee. Upon the issuance of such Convertible Notes, the Notes and the obligations of the Company and the guarantee thereunder have been canceled and extinguished. The Convertible Notes will mature on July 27, 2026, unless earlier converted, redeemed or repurchased. In connection with the exchange of Notes to Convertible Notes, the Company recognized accelerated amortization of the unamortized discount and deferred issuance costs relating to the Notes totaling $42 million, which was recorded within charges related to exchange of senior notes upon IPO in the Company’s condensed consolidated statement of operations for the three months and nine months ended September 30, 2021. Deferred financing costs related to Convertible Notes were not material. Interest on the Convertible Notes accrues from July 27, 2021 and is payable semi-annually in arrears on January 27 and July 27 of each year, beginning on January 27, 2022, at a rate of 2.95% per year. The initial conversion rate for the Convertible Notes is 40 shares of the Company’s common stock per $1,000 principal amount of Convertible Notes (equivalent to an initial conversion price of $25 per share of the Company’s common stock), subject to adjustment. The Company may not redeem the Convertible Notes prior to July 27, 2024. On or after July 27, 2024, the Company may redeem for cash all or any portion of the Convertible Notes, at its option, if the last reported sale price of the common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the Convertible Notes to be redeemed plus accrued and unpaid interest to, but excluding, the redemption date. In addition, calling any Convertible Note for redemption will constitute a “make-whole fundamental change” (as defined in the Indenture) with respect to that Convertible Note, in which case the conversion rate applicable to the conversion of that Convertible Note will be increased if it is converted by holders after it is called for redemption. Holders may convert all or any portion of their Convertible Notes, in multiples of $1,000 principal amount, into shares of the Company’s common stock at any time until the second scheduled trading day immediately preceding the maturity date, at the conversion rate then in effect. The Company will settle conversions of the Convertible Notes by paying or delivering, as the case may be, cash, shares of common stock, or a combination thereof, at its election. Upon the occurrence of a fundamental change (as defined in the Indenture), subject to certain conditions, holders of the Convertible Notes may require the Company to repurchase for cash all or any portion of their Convertible Notes in principal amounts of $1,000 or an integral multiple thereof, at a repurchase price of the principal amount of the Convertible Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the repurchase date. In addition, following certain corporate events that occur prior to the maturity date or if the Company delivers a notice of redemption, the Company will, in certain circumstances, increase the conversion rate for a holder who elects to convert its Convertible Notes in connection with such a corporate event or convert its Convertible Notes called for redemption during the related redemption period, as the case may be. The Indenture contains customary covenants and events of default. As described in Note 1, the Company early adopted ASU 2020-06 on January 1, 2021. The Company was not required to bifurcate the embedded conversion feature and the Convertible Notes were not issued with a substantial premium. As such, the Company accounted for the Convertible Notes as a liability under the no proceeds allocated model. The Company will calculate earnings per share using the if-converted method. Revolving Credit Facility The Company was party to a loan and security agreement (the “Revolving Credit Facility”) with Silicon Valley Bank (“SVB”), which matured on November 2, 2021, and prov ided the Company with an initial maximum borrowing capacity of up to $35.0 million that the Company could use to borrow against its qualifying receivables based on a defined borrowing formula. The Revolving Credit Facility contained customary conditions to borrowings, events of default and negative covenants, including covenants that restricted the Company's ability to dispose of assets, merge with or acquire other entities, incur indebtedness, incur encumbrances, make distributions to holders of its capital stock, make investments or engage in transactions with our affiliates. The Company was also subject to financial covenants with respect to a monthly modified liquidity ratio and Adjusted EBITDA for trailing six-month periods. Our obligations under the Revolving Credit Facility were secured by a first priority security interest in substantially all of the assets of the Company with a negative pledge on our intellectual property. The Company was in compliance with all financial covenants under its Revolving Credit Facility as of September 30, 2021. As of September 30, 2021 and December 31, 2020, we had no borrowings outstanding under our Revolving Credit Facility and our available borrowing capacity was $35.0 million based on the defined borrowing formul a. No borrowings were outstanding under the Revolving Credit Facility on the maturity date. On November 2, 2021, the Company entered into an Amended and Restated Loan and Security Agreement with SVB. See Note 12 for additional information.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s effective tax rates for the three months and nine months ended September 30, 2021 were (10.2)% and (36.2)%, respectively. The Company’s effective tax rates for the three and nine months ended September 30, 2020 were 0.2% and (47.4)%, respectively. The changes to the effective tax rates were primarily due to losses from operations in the current and prior year periods and the jurisdictional mix of earnings. The Company’s effective tax rate differed from the United States federal statutory tax rate of 21% primarily due to the full valuation allowance recorded against the U.S. deferred tax assets for the three and nine months ended September 30, 2021 , and our deferred tax assets in the U.S. and in one of our foreign subsidiaries for the three and nine months ended September 30, 2020, respectively.

Commitment and Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal Proceedings and Other Matters From time to time, we may become subject to legal proceedings, claims and litigation arising in the ordinary course of business. In addition, we may receive letters alleging infringement of patent or other intellectual property rights. We are not currently a party to any material legal proceedings, nor are we aware of any pending or threatened litigation that, in our opinion, would have a material adverse effect on our business, operating results, cash flows or financial condition should such litigation be resolved unfavorably. On April 29, 2021, we were notified that the Antitrust Division of the U.S. Department of Justice is conducting a criminal investigation into the hiring practices in our industry that includes us. We are cooperating with the Antitrust Division. While there can be no assurance regarding the ultimate resolution of this matter, we do not believe that our conduct violated applicable law. Lease Commitments We lease certain office and data center facilities under non-cancelable operating lease arrangements for our U.S. and international locations that expire on various dates through 2027. These arrangements require us to pay certain operating expenses, such as taxes, repairs and insurance and contain renewal and escalation clauses. We recognize rent expense under these arrangements on a straight-line basis over the term of the lease. In addition, we lease certain equipment and computers under capital lease arrangements that expire at various dates through 2024. As of September 30, 2021, the aggregate future non-cancelable minimum lease payments consist of the following: Year Operating Leases Capital Leases (In thousands) Remainder of 2021 $ 1,895 $ 1,121 2022 9,215 3,329 2023 8,804 1,741 2024 5,904 256 2025 5,773 — Thereafter 3,970 — Total minimum payments required $ 35,561 $ 6,447

Stock-based Compensation

Stock-based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-based Compensation	Stock-based Compensation In July 2021, the Board, and the Company’s stockholders approved, the 2021 Long-Term Incentive Plan (the “2021 LTIP”), which became effective in connection with the closing of the Company’s IPO. A total of 5,050,000 shares of the Company’s common stock have been reserved for issuance under the 2021 LTIP, which is subject to automatic annual increases. The 2021 LTIP may be used to grant, among other award types, stock options, restricted share awards (“RSAs”) and restricted stock units (“RSUs”). The number of shares of common stock reserved for future issuance under the 2021 Plan will also be increased pursuant to provisions for annual automatic evergreen increases. The Company’s previous awards issued under its 2007 Omnibus Securities and Incentive Plan, as amended and restated on January 21, 2009 (“2007 Plan”), remain subject to the 2007 Plan, including its lock-up provisions of up to 180 days after the IPO. As of September 30, 2021, approximately 526,438 and 5,050,000 shares were available for grant under the 2007 Plan and the 2021 LTIP, respectively. The Company recognizes stock-based compensation for stock-based awards, including stock options, RSAs, RSUs and stock appreciation rights (“SARs”) based on the estimated fair value of the awards. The Company estimates the fair value of its stock option awards on the grant date using the Black-Scholes option pricing model. The fair value of our RSAs and RSUs is the fair value of the Company’s common stock on the date of grant. In our accompanying condensed consolidated statements of operations, the Company recognized stock-based compensation for our employees and non-employees as follows: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (in thousands) (in thousands) Research and development $ 1,685 $ 207 $ 2,379 $ 574 Sales and marketing 5,587 508 6,926 1,525 General and administrative 11,176 159 12,091 633 Total stock-based compensation $ 18,448 (1) $ 874 $ 21,396 (1) $ 2,732 (1) Includes $16.5 million of stock-based compensation expense recorded during the three months ended September 30, 2021, in connection with the Company’s stock option awards, RSAs, RSUs and SARs for which the service condition has been met and a performance condition was satisfied upon the Company’s IPO, which was a qualifying liquidity event. Stock-based compensation expense for unvested awards will be recognized over the remainder of the requisite service period. As of September 30, 2021, the Company’s unrecognized stock-based compensation expense was $4.8 million for unvested stock options and $21.9 million for unvested RSUs. Determination of fair value The estimated grant-date fair value of our stock options was calculated using the Black-Scholes option pricing model, based on the following weighted-average assumptions: Nine Months Ended September 30, 2021 Expected term (in years) 6.0 years Risk-free interest rate 1.07 % Expected volatility 43.6 % Dividend rate — % Weighted-average grant date fair value $ 5.17 The following table summarizes stock option activity for the nine months ended September 30, 2021: Stock Options Number of Shares Weighted- Average Exercise Price Outstanding—December 31, 2020 5,475,481 $6.36 Granted 7,059 $12.33 Exercised (1,636,996) $3.14 Forfeited (288,735) $4.46 Outstanding—September 30, 2021 3,556,809 $8.01 Exercisable 2,660,253 $7.06 The following table summarizes RSA and RSU activity for the nine months ended September 30, 2021: RSAs and RSUs Number of Shares Weighted- Average Grant Date Fair Value Outstanding—December 31, 2020 4,036,409 $9.35 Granted 247,029 $12.33 Vested and released (392,376) $10.04 Forfeited (141,069) $10.49 Outstanding—September 30, 2021 3,749,993 ‘(1) $9.43 Outstanding and unvested 1,873,294 __________________________________________ (1) As of September 30, 2021, outstanding awards included 1,876,699 RSUs the delivery of which is deferred. In addition, as of September 30, 2021 and December 31, 2020, 3,390 SARs awards were outstanding with a weighted average grant date fair value of $3.93, which are accounted for as liability awards. Stock-Based Awards Granted Outside of Equity Incentive Plans Warrants The Company issued equity classified warrants to purchase shares of common stock to certain third-party advisors, consultants and financial institutions . In July 2021 , 244,619 w arrants that would have expired if not exercised prior to the Company’s IPO were exercised. A s of September 30, 2021, the Company had 376,470 warrants outstanding with a weighted exercise price of $7.81, which expire between 2024 and 2026. Employee Stock Purchase Plan In July 2021, the Board and the Company’s stockholders approved a new 2021 Employee Stock Purchase Plan (the “ESPP”), which became effective in connection with the closing of the Company’s IPO. A total of 1,263,000 shares of the Company’s common stock have been reserved for issuance under the ESPP, which is subject to automatic annual increases.

Net (Loss) Income Per Common Sh

Net (Loss) Income Per Common Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net (Loss) Income Per Common Share	Net (Loss) Income Per Common Share We apply the two-class method to calculate basic and diluted (loss) income per share attributable to common stockholders as shares of our convertible preferred stock are participating securities due to their participation rights. The two-class method is an earnings allocation method under which earnings per share is calculated for common stock considering a participating security holder’s rights to undistributed earnings as if all such earnings had been distributed during the period. Our participating securities are not included in the computation of loss per share attributable to common stockholders in periods of net loss because the convertible preferred stockholders have no contractual obligation to participate in losses. Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (In thousands, except share and per share data) Numerator: Basic and diluted: Net (loss) income $ (53,906) $ 2,541 $ (27,959) $ (9,652) Less: undistributed earnings allocated to participating securities — (1,577) — — Net (loss) income attributable to common stockholders $ (53,906) $ 964 $ (27,959) $ (9,652) Denominator: Basic weighted-average shares used in computing (loss) income attributable to common stockholders 47,859,056 16,846,853 27,645,471 16,747,054 Weighted average dilutive share equivalents: Stock options, Warrants, RSAs and RSUs — 2,613,257 — — Diluted weighted-average shares used in computing (loss) income attributable to common stockholders 47,859,056 19,460,110 27,645,471 16,747,054 Net (loss) income per share attributable to common stockholders: Basic $ (1.13) $ 0.06 $ (1.01) $ (0.58) Diluted $ (1.13) $ 0.05 $ (1.01) $ (0.58) The following weighted average shares have been excluded from the calculation of diluted (loss) income per share attributable to common stockholders for each period presented because they are anti-dilutive: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Convertible preferred stock 6,612,542 27,652,449 20,562,077 27,652,449 Options to purchase common stock 4,510,385 70,838 5,056,939 4,296,122 Warrants 434,454 — 558,194 621,089 Restricted stock units 3,933,167 488,591 4,161,050 2,444,752 Weighted average shares for convertible notes 7,182,609 — 2,420,513 — Total shares excluded from diluted (loss) income per share 22,673,157 28,211,878 32,758,773 35,014,412

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table summarizes the cash paid for interest and income taxes during the periods presented: Nine Months Ended September 30, 2021 2020 (in thousands) Cash paid for income taxes, net of refunds $ 3,485 $ 1,826 Cash paid for interest $ 476 $ 579 The following table presents the Company’s non-cash investing and financing activities for the periods presented: Nine Months Ended September 30, 2021 2020 (in thousands) Non-cash investing activities: Stock-based compensation capitalized for software development costs $ 134 $ 161 Purchases of property and equipment included in accounts payable 3 77 Property and equipment financed under capital obligation arrangements 1,837 4,406 Non-cash financing activities: Conversion of preferred stock to common stock $ 162,444 $ — Unpaid deferred offering costs and deferred financing costs in accounts payable and accrued expenses 2,484 —

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Credit Facility On November 2, 2021, the Company entered into an Amended and Restated Loan and Security Agreement with SVB (the “2021 Revolving Credit Facility”). The 2021 Revolving Credit Facility provides, subject to borrowing availability and certain other conditions, for revolving loans in an aggregate principal amount of up to $75.0 million (the “Facility”), with a $15 million sub-facility for letters of credit. The Company’s borrowing availability under the Facility is calculated by reference to a borrowing base which is determined by specified percentages of eligible accounts receivable. The Facility will terminate on the earlier of (i) November 2, 2026 or (ii) 120 days prior to the maturity date of the Company’s 2.95% Convertible Senior Notes due 2026, unless the Convertible Notes have been converted to common equity securities of the Company. Outstanding loans under the Facility accrue interest, at the Company’s option, at a rate equal to either (a) a base rate minus an applicable margin ranging from 1.5% to 1.0% per annum or (b) LIBOR plus an applicable margin of 1.5% to 2.0% per annum, in each case based upon borrowing availability under the Facility. The undrawn portions of the commitments under the Facility are subject to a commitment fee at a rate ranging from 0.20% per annum to 0.30% per annum, based upon borrowing availability under the Facility. The 2021 Revolving Credit Facility contains representations and warranties, including, without limitation, with respect to collateral; accounts receivable; financials; litigation, indictment and compliance with laws; disclosure and no material adverse effect, each of which is a condition to funding. Additionally, the 2021 Revolving Credit Facility includes events of default and customary affirmative and negative covenants applicable to the Company and its subsidiaries, including, without limitation, restrictions on liens, indebtedness, investments, fundamental changes, dispositions, restricted payments and prepayment of the Convertible Notes and of junior indebtedness. The 2021 Revolving Credit Facility contains a financial covenant that requires, in the event that credit extensions under the Facility equal or exceed 85% of the available commitments under the Facility or upon the occurrence of an event of default, the Company and its subsidiaries to maintain a minimum consolidated monthly fixed charge coverage ratio of 1.00. The obligations of the Company, and the other subsidiary co-borrowers under the 2021 Revolving Credit Facility are secured by a first-priority lien on substantially all the assets of the Company and such other subsidiary co-borrowers.

Organization, Description of _2

Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements were prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim financial information and are unaudited. Certain information and disclosures normally included in consolidated financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes for the year ended December 31, 2020, included with the Company’s final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on July 23, 2021.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and related disclosures as of the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. We base our estimates and judgments on historical information and on various other assumptions that we believe are reasonable under the circumstances. Estimates and assumptions made in the accompanying condensed consolidated financial statements include, but are not limited to, the allowance for doubtful accounts, sales allowance, software development costs eligible for capitalization, valuation of deferred tax assets, the useful lives of property and equipment, the useful lives and fair value of intangible assets and goodwill, the fair value of stock-based awards, the recognition and measurement of income tax uncertainties and other contingencies. Actual results could differ materially from these estimates.
Certain Risks and Concentrations	Certain Risks and Concentrations Financial instruments that potentially subject us to concentrations of credit risk consist of cash and cash equivalents, restricted cash and accounts receivable. Our cash and cash equivalents and restricted cash are generally invested in high-credit quality financial instruments with both banks and financial institutions to reduce the amount of exposure to any single financial institution.
Segment Information	Segment InformationWe have a single operating and reporting segment. Our chief operating decision maker is our Co-Chief Executive Officer who makes resource allocation decisions and assesses performance based on financial information presented on a consolidated basis.
Recently Adopted and Recently Issued Accounting Pronouncements	Recently Adopted and Recently Issued Accounting Pronouncements Under the JOBS Act, the Company meets the definition of an emerging growth company and 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 Company is no longer an emerging growth company or until the Company affirmatively and irrevocably opts out of the extended transition period. Recently adopted accounting pronouncements On January 1, 2021, we early adopted Accounting Standards Update (“ASU”) 2020-06, “Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity,” which simplified the accounting for convertible debt instruments by reducing the number of accounting models used to allocate proceeds from five to three, removing certain conditions for equity classification and amending earnings per share calculations to assume share settlement and to require the if-converted method to be applied to all convertible debt instruments. The adoption of this standard did not have an impact on our consolidated financial statements as of the date of adoption. The Company applied this guidance to its Convertible Notes issued in July 2021 (See Note 6 for additional information). Recently issued accounting pronouncements not yet adopted In February 2016, the Financial Accounting Standards Board (the “FASB”) issued ASU 2016-02, “Leases (Topic 842)”, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than twelve months, regardless of their classification. Leases with a term of twelve months or less will be accounted for similar to existing guidance for operating leases today. The new standard requires lessors to account for leases using an approach that is substantially equivalent to existing guidance for sales-type leases, direct financing leases and operating leases. ASU 2016-02 supersedes the previous leases standard, Leases (Topic 840). In June 2020 the FASB issued ASU 2020-05 Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities. The amendments in this update defer the effective date of ASU 2016-02 for private companies to fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. Early application is permitted. The Company plans to adopt this standard on January 1, 2022, as required. The Company has aggregated all of its lease agreements and is in the process of analyzing its lease portfolio and assessing the impacts of adoption on its consolidated financial statements. The Company expects its assets and liabilities to increase in connection with the recording of right-of-use assets and lease liabilities upon adoption of this standard. In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326),” which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model which requires consideration of forward-looking information to calculate credit loss estimates. These changes will result in an earlier recognition of credit losses. The Company's financial assets held at amortized cost include accounts receivable. The amendments in ASU 2020-05 deferred the effective date for Topic 326 to fiscal years beginning after December 15, 2022. The Company plans to adopt this standard on the earlier of January 1, 2023 or on losing its emerging growth company status. The Company does not expect the adoption of this standard will have a material impact on the consolidated financial statements or related disclosures. See Note 1 to the Company’s audited consolidated financial statements for the year ended December 31, 2020 in our final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on July 23, 2021 for a complete disclosure of the Company’s significant accounting policies.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Total Revenue by Physical Location of Marketers	The following table presents total revenue based on where our marketers are physically located: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (In thousands) (In thousands) USA $ 94,599 $ 73,666 $ 265,677 $ 201,447 Europe, the Middle East and Africa (EMEA) 125,102 93,719 377,680 263,543 Other 31,083 19,125 82,604 56,714 Total revenue $ 250,784 $ 186,510 $ 725,961 $ 521,704

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets Measured on Recurring Basis	The following table sets forth the fair value of our financial assets measured on a recurring basis by level within the fair value hierarchy: September 30, 2021 Level I Level II Level III Total (In thousands) Financial Assets: Restricted time deposit (1) $ — $ 402 $ — $ 402 Severance pay fund deposits (1) $ — $ 5,315 $ — $ 5,315 Foreign currency forward contract (2) $ — $ 77 $ — $ 77 Total financial assets $ — $ 5,794 $ — $ 5,794 December 31, 2020 Level I Level II Level III Total (In thousands) Financial Assets: Restricted time deposit (1) $ — $ 426 $ — $ 426 Severance pay fund deposits (1) $ — $ 5,379 $ — $ 5,379 Foreign currency forward contract (2) $ — $ 553 $ — $ 553 Total financial assets $ — $ 6,358 $ — $ 6,358 _____________________ (1) Recorded within other assets (2) Recorded within prepaid expenses and other current assets
Schedule of Fair Value, Liabilities Measured on Nonrecurring Basis	The following table summarizes the carrying value and the estimated fair value of the Company’s Convertible Notes, based on Level II measurements of the fair value hierarchy: September 30, December 31, Carrying Value Estimated Fair Value Carrying Value Estimated Fair Value (In thousands) Convertible Notes $ 236,000 $ 240,531 $ — $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts Receivable, Net of Allowance	Accounts receivable, net of allowances consists of the following: September 30, December 31, (In thousands) Accounts receivable $ 165,844 $ 169,623 Allowance for doubtful accounts (4,519) (4,174) Accounts receivable, net of allowances $ 161,325 $ 165,449
Activity in Allowance for Doubtful Accounts	The allowance for doubtful accounts consists of the following activity: Nine Months Ended September 30, 2021 Year Ended December 31, 2020 (In thousands) Allowance for doubtful accounts, beginning balance $ 4,174 $ 3,281 Provision for doubtful accounts, net of recoveries 2,155 2,668 Write-offs (1,810) (1,775) Allowance for doubtful accounts, ending balance $ 4,519 $ 4,174
Property, Equipment and Capitalized Software, Net	Property, equipment and capitalized software, net consists of the following: September 30, December 31, 2020 (In thousands) Computer equipment $ 38,354 $ 41,735 Capitalized software development costs 51,295 43,728 Software 2,947 3,444 Leasehold improvements 1,245 2,805 Furniture and fixtures 252 908 Property, equipment and capitalized software, gross 94,093 92,620 Less: accumulated depreciation and amortization (69,311) (67,864) Total property, equipment and capitalized software, net $ 24,782 $ 24,756

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The gross carrying amount and accumulated amortization of our intangible assets are as follows: As of September 30, 2021 Amortization Gross Value Accumulated Net Carrying (In thousands) Developed technology 36-48 months $ 8,425 $ (8,425) $ — Customer relationships 48 months 5,445 (3,853) 1,592 Publisher relationships 48 months 8,606 (5,379) 3,227 Trade names 8 years 1,705 (533) 1,172 Other 14 years 870 (157) 713 Total intangible assets, net $ 25,051 $ (18,347) $ 6,704 As of December 31, 2020 Amortization Gross Value Accumulated Net Carrying (In thousands) Developed technology 36-48 months $ 8,425 $ (8,388) $ 37 Customer relationships 48 months 5,694 (3,166) 2,528 Publisher relationships 48 months 9,111 (3,986) 5,125 Trade names 8 years 1,805 (395) 1,410 Other 14 years 830 (118) 712 Total intangible assets, net $ 25,865 $ (16,053) $ 9,812
Schedule of Estimated Amortization on Identifiable Acquisition-Related Intangible Assets	As of September 30, 2021, estimated amortization related to our identifiable acquisition-related intangible assets in future periods was as follows: Year Amount (In thousands) Remainder of 2021 $ 870 2022 3,479 2023 1,069 2024 266 2025 266 Thereafter 754 Total $ 6,704

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Aggregate Future Non-cancelable Minimum Lease Payments	As of September 30, 2021, the aggregate future non-cancelable minimum lease payments consist of the following: Year Operating Leases Capital Leases (In thousands) Remainder of 2021 $ 1,895 $ 1,121 2022 9,215 3,329 2023 8,804 1,741 2024 5,904 256 2025 5,773 — Thereafter 3,970 — Total minimum payments required $ 35,561 $ 6,447
Aggregate Future Non-cancelable Minimum Lease Payments	As of September 30, 2021, the aggregate future non-cancelable minimum lease payments consist of the following: Year Operating Leases Capital Leases (In thousands) Remainder of 2021 $ 1,895 $ 1,121 2022 9,215 3,329 2023 8,804 1,741 2024 5,904 256 2025 5,773 — Thereafter 3,970 — Total minimum payments required $ 35,561 $ 6,447

Stock-based Compensation (Table

Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation	In our accompanying condensed consolidated statements of operations, the Company recognized stock-based compensation for our employees and non-employees as follows: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (in thousands) (in thousands) Research and development $ 1,685 $ 207 $ 2,379 $ 574 Sales and marketing 5,587 508 6,926 1,525 General and administrative 11,176 159 12,091 633 Total stock-based compensation $ 18,448 (1) $ 874 $ 21,396 (1) $ 2,732 (1)
Schedule of Weighted-Average Assumptions	The estimated grant-date fair value of our stock options was calculated using the Black-Scholes option pricing model, based on the following weighted-average assumptions: Nine Months Ended September 30, 2021 Expected term (in years) 6.0 years Risk-free interest rate 1.07 % Expected volatility 43.6 % Dividend rate — % Weighted-average grant date fair value $ 5.17
Summary of Award Activity	The following table summarizes stock option activity for the nine months ended September 30, 2021: Stock Options Number of Shares Weighted- Average Exercise Price Outstanding—December 31, 2020 5,475,481 $6.36 Granted 7,059 $12.33 Exercised (1,636,996) $3.14 Forfeited (288,735) $4.46 Outstanding—September 30, 2021 3,556,809 $8.01 Exercisable 2,660,253 $7.06 The following table summarizes RSA and RSU activity for the nine months ended September 30, 2021: RSAs and RSUs Number of Shares Weighted- Average Grant Date Fair Value Outstanding—December 31, 2020 4,036,409 $9.35 Granted 247,029 $12.33 Vested and released (392,376) $10.04 Forfeited (141,069) $10.49 Outstanding—September 30, 2021 3,749,993 ‘(1) $9.43 Outstanding and unvested 1,873,294 __________________________________________ (1) As of September 30, 2021, outstanding awards included 1,876,699 RSUs the delivery of which is deferred.

Net (Loss) Income Per Common _2

Net (Loss) Income Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 (In thousands, except share and per share data) Numerator: Basic and diluted: Net (loss) income $ (53,906) $ 2,541 $ (27,959) $ (9,652) Less: undistributed earnings allocated to participating securities — (1,577) — — Net (loss) income attributable to common stockholders $ (53,906) $ 964 $ (27,959) $ (9,652) Denominator: Basic weighted-average shares used in computing (loss) income attributable to common stockholders 47,859,056 16,846,853 27,645,471 16,747,054 Weighted average dilutive share equivalents: Stock options, Warrants, RSAs and RSUs — 2,613,257 — — Diluted weighted-average shares used in computing (loss) income attributable to common stockholders 47,859,056 19,460,110 27,645,471 16,747,054 Net (loss) income per share attributable to common stockholders: Basic $ (1.13) $ 0.06 $ (1.01) $ (0.58) Diluted $ (1.13) $ 0.05 $ (1.01) $ (0.58)
Schedule of Weighted Average Shares Excluded From Calculation of Diluted Income (Loss) Per Share	The following weighted average shares have been excluded from the calculation of diluted (loss) income per share attributable to common stockholders for each period presented because they are anti-dilutive: Three Months Ended Nine Months Ended 2021 2020 2021 2020 Convertible preferred stock 6,612,542 27,652,449 20,562,077 27,652,449 Options to purchase common stock 4,510,385 70,838 5,056,939 4,296,122 Warrants 434,454 — 558,194 621,089 Restricted stock units 3,933,167 488,591 4,161,050 2,444,752 Weighted average shares for convertible notes 7,182,609 — 2,420,513 — Total shares excluded from diluted (loss) income per share 22,673,157 28,211,878 32,758,773 35,014,412

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Summary of Cash Paid for Interest and Income Taxes	The following table summarizes the cash paid for interest and income taxes during the periods presented: Nine Months Ended September 30, 2021 2020 (in thousands) Cash paid for income taxes, net of refunds $ 3,485 $ 1,826 Cash paid for interest $ 476 $ 579
Non-cash Investing and Financing Activities	The following table presents the Company’s non-cash investing and financing activities for the periods presented: Nine Months Ended September 30, 2021 2020 (in thousands) Non-cash investing activities: Stock-based compensation capitalized for software development costs $ 134 $ 161 Purchases of property and equipment included in accounts payable 3 77 Property and equipment financed under capital obligation arrangements 1,837 4,406 Non-cash financing activities: Conversion of preferred stock to common stock $ 162,444 $ — Unpaid deferred offering costs and deferred financing costs in accounts payable and accrued expenses 2,484 —

Organization, Description of _3

Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements - Initial Public Offering (Details) $ / shares in Units, $ in Thousands	Jul. 27, 2021USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Jul. 31, 2021$ / sharesshares	Dec. 31, 2020$ / sharesshares
Subsidiary, Sale of Stock [Line Items]
Number of shares issued upon conversion of convertible preferred stock	28,091,267	27,652,449	27,652,449
Convertible preferred stock, conversion ratio	1
Carrying value of convertible preferred stock reclassified to equity | $	$ 162,400	$ 162,444	$ 162,444
Common and preferred stock, shares authorized				1,100,000,000
Common stock, shares authorized		1,000,000,000	1,000,000,000	1,000,000,000	65,183,785
Common stock, par value (in usd per share) | $ / shares		$ 0.001	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized				100,000,000
Preferred stock, par value (in usd per share) | $ / shares				$ 0.001
Series F Preferred Stock
Subsidiary, Sale of Stock [Line Items]
Convertible preferred stock, conversion ratio	1.14
IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued	8,000,000
Stock price (in usd per share) | $ / shares	$ 20
Net proceeds from sale of stock | $	$ 145,100
Deferred offering costs | $	$ 3,700

Organization, Description of _4

Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements - Basis of Presentation (Details)	Jul. 13, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Reverse stock split ratio	0.5882

Organization, Description of _5

Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements - Certain Risks and Concentrations (Details) - Revenue Benchmark - Customer Concentration Risk	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Customer A
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%	13.00%	10.00%	11.00%
Customer B
Concentration Risk [Line Items]
Concentration risk, percentage	10.00%		11.00%	13.00%

Organization, Description of _6

Organization, Description of Business, Basis of Presentation, Use of Estimates and Recently Issued Accounting Pronouncements - Segment Information (Details)	9 Months Ended
	Sep. 30, 2021segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segment	1
Number of operating segment	1

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue	$ 250,784	$ 186,510	$ 725,961	$ 521,704
USA
Disaggregation of Revenue [Line Items]
Revenue	94,599	73,666	265,677	201,447
Europe, the Middle East and Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenue	125,102	93,719	377,680	263,543
Other
Disaggregation of Revenue [Line Items]
Revenue	$ 31,083	$ 19,125	$ 82,604	$ 56,714

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contract assets	$ 0	$ 0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets	$ 5,794	$ 6,358
Foreign currency forward contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset	77	553
Restricted time deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	402	426
Severance pay fund deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	5,315	5,379
Level I
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets	0	0
Level I | Foreign currency forward contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset	0	0
Level I | Restricted time deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	0	0
Level I | Severance pay fund deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	0	0
Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets	5,794	6,358
Level II | Foreign currency forward contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset	77	553
Level II | Restricted time deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	402	426
Level II | Severance pay fund deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	5,315	5,379
Level III
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total financial assets	0	0
Level III | Foreign currency forward contract
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative asset	0	0
Level III | Restricted time deposit
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	0	0
Level III | Severance pay fund deposits
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets	$ 0	$ 0

Fair Value Measurements - Fin_2

Fair Value Measurements - Financial Liabilities Measured on Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jul. 27, 2021	Dec. 31, 2020
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Notes	$ 236,000		$ 0
Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Notes	$ 240,531		$ 0
Convertible notes | 2.95% Convertible Senior Notes Due 2026
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate		2.95%

Balance Sheet Components - Acco

Balance Sheet Components - Accounts Receivable, Net of Allowance (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts receivable	$ 165,844	$ 169,623
Allowance for doubtful accounts	(4,519)	(4,174)	$ (3,281)
Accounts receivable, net of allowances	$ 161,325	$ 165,449

Balance Sheet Components - Allo

Balance Sheet Components - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for doubtful accounts, beginning balance	$ 4,174	$ 3,281
Provision for doubtful accounts, net of recoveries	2,155	2,668
Write-offs	(1,810)	(1,775)
Allowance for doubtful accounts, ending balance	$ 4,519	$ 4,174

Balance Sheet Components - Prop

Balance Sheet Components - Property, Equipment and Capitalized Software (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	$ 94,093	$ 92,620
Less: accumulated depreciation and amortization	(69,311)	(67,864)
Total property, equipment and capitalized software, net	24,782	24,756
Computer equipment
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	38,354	41,735
Capitalized software development costs
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	51,295	43,728
Software
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	2,947	3,444
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	1,245	2,805
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	$ 252	$ 908

Balance Sheet Components - Curr

Balance Sheet Components - Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Separate Account, Liability [Line Items]
Accrued and other current liabilities	$ 104,066	$ 109,747
Accrued And Other Liabilities, Current
Separate Account, Liability [Line Items]
Traffic acquisition costs in current liabilities	64,400	77,200
Accounts Payable
Separate Account, Liability [Line Items]
Traffic acquisition costs in current liabilities	$ 129,800	$ 111,700

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 32,881		$ 32,881		$ 32,881
Accumulated impairments of goodwill	0		0		$ 0
Impairment charges	$ 0	$ 0	$ 0	$ 0

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets, Net (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross Value	$ 25,051	$ 25,865
Accumulated Amortization	(18,347)	(16,053)
Net Value	6,704	9,812
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Value	8,425	8,425
Accumulated Amortization	(8,425)	(8,388)
Net Value	$ 0	$ 37
Developed technology | Minimum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	36 months	36 months
Developed technology | Maximum
Finite-Lived Intangible Assets [Line Items]
Amortization Period	48 months	48 months
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Amortization Period	48 months	48 months
Gross Value	$ 5,445	$ 5,694
Accumulated Amortization	(3,853)	(3,166)
Net Value	$ 1,592	$ 2,528
Publisher relationships
Finite-Lived Intangible Assets [Line Items]
Amortization Period	48 months	48 months
Gross Value	$ 8,606	$ 9,111
Accumulated Amortization	(5,379)	(3,986)
Net Value	$ 3,227	$ 5,125
Trade names
Finite-Lived Intangible Assets [Line Items]
Amortization Period	8 years	8 years
Gross Value	$ 1,705	$ 1,805
Accumulated Amortization	(533)	(395)
Net Value	$ 1,172	$ 1,410
Other
Finite-Lived Intangible Assets [Line Items]
Amortization Period	14 years	14 years
Gross Value	$ 870	$ 830
Accumulated Amortization	(157)	(118)
Net Value	$ 713	$ 712

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Estimated Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 870
2022	3,479
2023	1,069
2024	266
2025	266
Thereafter	754
Net Value	$ 6,704	$ 9,812

Long Term Debt - Convertible No

Long Term Debt - Convertible Notes (Details)	Jul. 27, 2021USD ($)day$ / shares	Jul. 01, 2021USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)
Debt Instrument [Line Items]
Charges related to exchange of senior notes upon IPO			$ 42,049,000	$ 0	$ 42,049,000	$ 0
Convertible notes | 2.95% Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Interest rate	2.95%
Aggregate principal amount	$ 236,000,000
Conversion rate	0.04
Conversion price (in usd per share) | $ / shares	$ 25
Threshold percentage of stock price trigger	130.00%
Threshold trading days | day	20
Threshold consecutive trading days | day	30
Redemption price, percentage	100.00%
Secured Notes | Senior Subordinated Secured Notes Due July 1, 2026
Debt Instrument [Line Items]
Debt discount		$ 36,000,000
Deferred financing costs		$ 6,000,000
Secured Notes | Senior Subordinated Secured Notes Due July 1, 2026 | Minimum
Debt Instrument [Line Items]
Interest rate		10.00%
Secured Notes | Senior Subordinated Secured Notes Due July 1, 2026 | Maximum
Debt Instrument [Line Items]
Interest rate		14.50%
Secured Notes | Senior Subordinated Secured Notes Due July 1, 2026
Debt Instrument [Line Items]
Amount of debt sold		$ 200,000,000
Charges related to exchange of senior notes upon IPO			$ 42,000,000		$ 42,000,000

Long Term Debt - Revolving Cred

Long Term Debt - Revolving Credit Facility (Details) - Revolving Credit Facility - USD ($)	9 Months Ended
	Sep. 30, 2021	Nov. 02, 2021	Dec. 31, 2020
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 35,000,000
Trailing period	6 months
Borrowings outstanding	$ 0		$ 0
Available borrowing capacity	$ 35,000,000
Subsequent Event
Line of Credit Facility [Line Items]
Borrowings outstanding		$ 0

Income Taxes (Details)

Income Taxes (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	(10.20%)	0.20%	(36.20%)	(47.40%)

Commitment and Contingencies (D

Commitment and Contingencies (Details) $ in Thousands	Sep. 30, 2021USD ($)
Operating Leases
Remainder of 2021	$ 1,895
2022	9,215
2023	8,804
2024	5,904
2025	5,773
Thereafter	3,970
Total minimum payments required	35,561
Capital Leases
Remainder of 2021	1,121
2022	3,329
2023	1,741
2024	256
2025	0
Thereafter	0
Total minimum payments required	$ 6,447

Stock-based Compensation - Narr

Stock-based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 27, 2021	Jul. 27, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation			$ 18,448	$ 874	$ 21,396	$ 2,732
Number of warrants exercised (in shares)		244,619
Number of warrants outstanding (in shares)			376,470		376,470
Weighted Average
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of warrants (in usd per share)			$ 7.81		$ 7.81
Stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation related to unvested awards			$ 4,800		$ 4,800
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation related to unvested awards			$ 21,900		$ 21,900
SAR
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares outstanding			3,390		3,390		3,390
Weighted average grant date fair value of outstanding shares (in usd per share)			$ 3.93		$ 3.93		$ 3.93
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance	1,263,000	1,263,000
Vest upon satisfaction of a performance condition
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation			$ 16,500		$ 16,500
LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for future issuance	5,050,000	5,050,000
Number of shares available for grant			5,050,000		5,050,000
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Lock-up provision, period	180 days
Number of shares available for grant			526,438		526,438

Stock-based Compensation - Sche

Stock-based Compensation - Schedule of Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 18,448	$ 874	$ 21,396	$ 2,732
Vest upon satisfaction of a performance condition
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	16,500		16,500
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	1,685	207	2,379	574
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	5,587	508	6,926	1,525
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 11,176	$ 159	$ 12,091	$ 633

Stock-based Compensation - Weig

Stock-based Compensation - Weighted-Average Assumptions (Details)	9 Months Ended
	Sep. 30, 2021$ / shares
Share-based Payment Arrangement [Abstract]
Expected term (in years)	6 years
Risk-free interest rate	1.07%
Expected volatility	43.60%
Dividend rate	0.00%
Weighted-average grant date fair value (in usd per share)	$ 5.17

Stock-based Compensation - Awar

Stock-based Compensation - Award Activity (Details) - $ / shares	9 Months Ended
	Sep. 30, 2021
Options, Outstanding, Number of Shares
Outstanding - beginning of period (in shares)	5,475,481
Granted (in shares)	7,059
Exercised (in shares)	(1,636,996)
Forfeited (in shares)	(288,735)
Outstanding - end of period (in shares)	3,556,809
Exercisable (in shares)	2,660,253
Options Outstanding, Weighted Average Exercise Price
Outstanding - beginning of period (in usd per share)	$ 6.36
Granted (in usd per share)	12.33
Exercised (in usd per share)	3.14
Forfeited (in usd per share)	4.46
Outstanding - end of period (in usd per share)	8.01
Exercisable (in usd per share)	$ 7.06
RSAs and RSUs
RSAs and RSUs Unvested and Outstanding, Number of Shares
Outstanding - beginning of period (in shares)	4,036,409
Granted (in shares)	247,029
Vested (in shares)	(392,376)
Forfeited (in shares)	(141,069)
Outstanding - end of period (in shares)	3,749,993
Outstanding and unvested (in shares)	1,873,294
RSAs and RSUs Unvested and Outstanding, Weighted-Average Grant Date Fair Value
Outstanding - beginning of period (in usd per share)	$ 9.35
Granted (in usd per share)	12.33
Vested (in usd per share)	10.04
Forfeited (in usd per share)	10.49
Outstanding - end of period (in usd per share)	$ 9.43
Deferred Delivery, RSUs
RSAs and RSUs Unvested and Outstanding, Number of Shares
Outstanding - end of period (in shares)	1,876,699

Net (Loss) Income Per Common _3

Net (Loss) Income Per Common Share - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Numerator, Basic:
Net (loss) income	$ (53,906)	$ 2,541	$ (27,959)	$ (9,652)
Less: undistributed earnings allocated to participating securities	0	(1,577)	0	0
Net (loss) income attributable to common stockholders	(53,906)	964	(27,959)	(9,652)
Numerator, Diluted:
Net (loss) income	(53,906)	2,541	(27,959)	(9,652)
Less: undistributed earnings allocated to participating securities	0	(1,577)	0	0
Net (loss) income attributable to common stockholders	$ (53,906)	$ 964	$ (27,959)	$ (9,652)
Denominator:
Basic weighted-average shares used in computing (loss) income attributable to common stockholders (in shares)	47,859,056	16,846,853	27,645,471	16,747,054
Weighted average dilutive share equivalents: Stock options, Warrants, RSAs and RSUs (in shares)	0	2,613,257	0	0
Diluted weighted-average shares used in computing (loss) income attributable to common stockholders (in shares)	47,859,056	19,460,110	27,645,471	16,747,054
Net (loss) income per share attributable to common stockholders:
Basic (in usd per share)	$ (1.13)	$ 0.06	$ (1.01)	$ (0.58)
Diluted (in usd per share)	$ (1.13)	$ 0.05	$ (1.01)	$ (0.58)

Net (Loss) Income Per Common _4

Net (Loss) Income Per Common Share - Antidilutive Shares (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from diluted (loss) income per share	22,673,157	28,211,878	32,758,773	35,014,412
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from diluted (loss) income per share	6,612,542	27,652,449	20,562,077	27,652,449
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from diluted (loss) income per share	4,510,385	70,838	5,056,939	4,296,122
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from diluted (loss) income per share	434,454	0	558,194	621,089
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from diluted (loss) income per share	3,933,167	488,591	4,161,050	2,444,752
Weighted average shares for convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from diluted (loss) income per share	7,182,609	0	2,420,513	0

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information - Cash Paid for Interest and Income Taxes (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Cash paid for income taxes, net of refunds	$ 3,485	$ 1,826
Cash paid for interest	$ 476	$ 579

Supplemental Cash Flow Inform_4

Supplemental Cash Flow Information - Non-cash Investing and Financing Activities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Non-cash investing activities:
Stock-based compensation capitalized for software development costs	$ 134	$ 161
Purchases of property and equipment included in accounts payable	3	77
Property and equipment financed under capital obligation arrangements	1,837	4,406
Non-cash financing activities:
Conversion of preferred stock to common stock	162,444	0
Unpaid deferred offering costs and deferred financing costs in accounts payable and accrued expenses	$ 2,484	$ 0

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Nov. 02, 2021	Jul. 27, 2021
Convertible notes | 2.95% Convertible Senior Notes Due 2026
Subsequent Event [Line Items]
Interest rate		2.95%
Subsequent Event | Convertible notes | 2.95% Convertible Senior Notes Due 2026
Subsequent Event [Line Items]
Interest rate	2.95%
Subsequent Event | 2021 Revolving Credit Facility
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 75,000,000
Period prior to maturity date of convertible notes	120 days
Percentage of available commitments	85.00%
Minimum consolidated monthly fixed charge coverage ratio	1
Subsequent Event | 2021 Revolving Credit Facility | Minimum
Subsequent Event [Line Items]
Commitment fee percentage	0.20%
Subsequent Event | 2021 Revolving Credit Facility | Maximum
Subsequent Event [Line Items]
Commitment fee percentage	0.30%
Subsequent Event | 2021 Revolving Credit Facility | Base Rate | Minimum
Subsequent Event [Line Items]
Margin rate	1.00%
Subsequent Event | 2021 Revolving Credit Facility | Base Rate | Maximum
Subsequent Event [Line Items]
Margin rate	1.50%
Subsequent Event | 2021 Revolving Credit Facility | LIBOR | Minimum
Subsequent Event [Line Items]
Margin rate	1.50%
Subsequent Event | 2021 Revolving Credit Facility | LIBOR | Maximum
Subsequent Event [Line Items]
Margin rate	2.00%
Subsequent Event | Letter of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity	$ 15,000,000