Fastly (FSLY) 10-Q 6 Nov 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares shares in Millions	9 Months Ended
	Sep. 30, 2020	Oct. 31, 2020
Entity Listings [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2020
Document Transition Report	false
Entity File Number	001-38897
Entity Registrant Name	FASTLY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-5411834
Entity Address, Address Line One	475 Brannan Street, Suite 300
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94107
City Area Code	844
Local Phone Number	432-7859
Title of 12(b) Security	Class A Common Stock, $0.00002 par value
Trading Symbol	FSLY
Security Exchange Name	NYSE
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 Central Index Key	0001517413
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		102.4
Common Class B
Entity Listings [Line Items]
Entity Common Stock, Shares Outstanding		11.1

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 309,968	$ 16,142
Marketable securities	92,302	114,967
Accounts receivable, net of allowance for doubtful accounts of $2,761 and $1,816 as of September 30, 2020 and December 31, 2019, respectively	42,593	37,136
Restricted cash	70,087	70,087
Prepaid expenses and other current assets	14,769	10,991
Total current assets	529,719	249,323
Property and equipment, net	83,498	60,037
Goodwill	362	372
Intangible assets, net	2,792	1,125
Other assets	15,147	10,112
Total assets	631,518	320,969
Current liabilities:
Accounts payable	12,273	4,602
Accrued expenses	38,559	19,878
Current portion of long-term debt	6,060	4,472
Other current liabilities	9,555	8,169
Total current liabilities	66,447	37,121
Long-term debt, less current portion	26,007	25,158
Other long-term liabilities	3,944	1,038
Total liabilities	96,398	63,317
Commitments and contingencies (Note 8)
Stockholders’ equity:
Class A and Class B common stock	2	2
Additional paid-in capital	777,231	449,463
Accumulated other comprehensive income	124	196
Accumulated deficit	(242,237)	(192,009)
Total stockholders’ equity	535,120	257,652
Total liabilities and stockholders’ equity	$ 631,518	$ 320,969

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 2,761	$ 1,816

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenue	$ 70,638	$ 49,797	$ 208,225	$ 141,526
Cost of revenue	29,292	22,292	86,254	62,794
Gross profit	41,346	27,505	121,971	78,732
Operating expenses:
Research and development	18,271	12,121	49,224	33,541
Sales and marketing	22,568	17,560	66,416	49,505
General and administrative	23,961	10,583	56,199	28,203
Total operating expenses	64,800	40,264	171,839	111,249
Loss from operations	(23,454)	(12,759)	(49,868)	(32,517)
Interest income	353	1,154	1,450	2,431
Interest expense	(410)	(621)	(1,097)	(4,845)
Other income (expense), net	69	109	418	(2,363)
Loss before income taxes	(23,442)	(12,117)	(49,097)	(37,294)
Income taxes	336	46	1,131	183
Net loss	$ (23,778)	$ (12,163)	$ (50,228)	$ (37,477)
Net loss per share attributable to common stockholders, basic and diluted (in USD per share)	$ (0.22)	$ (0.13)	$ (0.50)	$ (0.63)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	105,942	93,240	100,413	59,679

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Other Comprehensive Income [Abstract]
Net income (loss)	$ (23,778)	$ (12,163)	$ (50,228)	$ (37,477)
Other comprehensive income:
Foreign currency translation adjustment	(68)	(12)	(149)	(5)
Gain (loss) on investments in available-for-sale-securities, net of tax	(193)	(23)	77	19
Total other comprehensive income (loss)	(261)	(35)	(72)	14
Comprehensive loss	$ (24,039)	$ (12,198)	$ (50,300)	$ (37,463)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Class B	Convertible Preferred Stock	Common StockCommon Class A	Common StockCommon Class B	Additional Paid-in Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Accumulated DeficitCumulative Effect, Period of Adoption, Adjustment
Convertible preferred stock, beginning balance (in shares) at Dec. 31, 2018				53,630,213
Convertible Preferred Stock, beginning balance at Dec. 31, 2018				$ 219,584
Convertible Preferred Stock
Conversion of stock (in shares)			224,102	53,630,213		53,630,213
Conversion of stock	$ 219,584			$ (219,584)		$ 1	$ 219,583
Convertible preferred stock, ending balance (in shares) at Sep. 30, 2019				0
Convertible Preferred Stock, ending balance at Sep. 30, 2019				$ 0
Beginning balance (in shares) at Dec. 31, 2018					0	25,025,836
Beginning balance at Dec. 31, 2018	(131,927)	$ 5,727			$ 0	$ 1	16,403	$ (2,109)	$ (36)	$ (146,186)	$ 5,727
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)					164,691	1,211,230
Exercise of stock options	2,828						2,828
Exercise of common stock warrants (in shares)						224,102
Vesting of early exercised stock options (in shares)						121,579
Vesting of early exercised stock options	465						465
Stock-based compensation	7,550						7,550
Conversion of stock (in shares)			224,102	53,630,213		53,630,213
Conversion of stock	219,584			$ (219,584)		$ 1	219,583
Conversion of convertible preferred stock warrants into Class B common stock warrants	5,665						5,665
Shares issued (in shares)					12,937,500
Shares issued	186,912						186,912
Repayment of stockholder note (in shares)						31,939
Repayment of stockholder note	74						74
Net income (loss)	(37,477)									(37,477)
Other comprehensive income (loss)	14								14
Ending balance (in shares) at Sep. 30, 2019					13,102,191	80,244,899
Ending balance at Sep. 30, 2019	259,415				$ 0	$ 2	439,480	(2,109)	(22)	(177,936)
Convertible Preferred Stock
Conversion of stock (in shares)			51,722
Convertible preferred stock, ending balance (in shares) at Sep. 30, 2019				0
Convertible Preferred Stock, ending balance at Sep. 30, 2019				$ 0
Beginning balance (in shares) at Jun. 30, 2019					12,995,158	80,152,652
Beginning balance at Jun. 30, 2019	267,322				$ 0	$ 2	435,189	(2,109)	13	(165,773)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)					107,033	0
Exercise of stock options	296						296
Exercise of common stock warrants (in shares)						51,722
Vesting of early exercised stock options (in shares)						40,525
Vesting of early exercised stock options	155						155
Stock-based compensation	3,840						3,840
Conversion of stock (in shares)			51,722
Net income (loss)	(12,163)									(12,163)
Other comprehensive income (loss)	(35)								(35)
Ending balance (in shares) at Sep. 30, 2019					13,102,191	80,244,899
Ending balance at Sep. 30, 2019	$ 259,415				$ 0	$ 2	439,480	$ (2,109)	(22)	(177,936)
Convertible preferred stock, beginning balance (in shares) at Dec. 31, 2019	0
Convertible Preferred Stock
Conversion of stock (in shares)			144,635,000		22,727,685	22,727,685
Convertible preferred stock, ending balance (in shares) at Sep. 30, 2020	0
Beginning balance (in shares) at Dec. 31, 2019					60,954,694	33,863,021
Beginning balance at Dec. 31, 2019	$ 257,652				$ 1	$ 1	449,463		196	(192,009)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	3,803,000				3,802,613
Exercise of stock options	$ 12,953						12,953
Exercise of common stock warrants (in shares)						144,635
Vesting of early exercised stock options (in shares)						94,048
Vesting of early exercised stock options	401						401
Vesting of restricted stock units (in shares)					905,093
Stock-based compensation	35,990						35,990
Conversion of stock (in shares)			144,635,000		22,727,685	22,727,685
Shares issued (in shares)					6,900,000
Shares issued	274,177						274,177
Shares purchased under ESPP (in shares)					226,288
Shares issued under ESPP	4,247						4,247
Net income (loss)	(50,228)									(50,228)
Other comprehensive income (loss)	(72)								(72)
Ending balance (in shares) at Sep. 30, 2020					95,516,373	11,374,019
Ending balance at Sep. 30, 2020	$ 535,120				$ 1	$ 1	777,231		124	(242,237)
Convertible Preferred Stock
Conversion of stock (in shares)			0		3,371,024	(3,371,024)
Convertible preferred stock, ending balance (in shares) at Sep. 30, 2020	0
Beginning balance (in shares) at Jun. 30, 2020					90,321,462	14,716,313
Beginning balance at Jun. 30, 2020	$ 542,165				$ 1	$ 1	760,237		385	(218,459)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)					979,252
Exercise of stock options	4,122						4,122
Vesting of early exercised stock options (in shares)						28,730
Vesting of early exercised stock options	127						127
Vesting of restricted stock units (in shares)					844,635
Stock-based compensation	12,745						12,745
Conversion of stock (in shares)			0		3,371,024	(3,371,024)
Net income (loss)	(23,778)									(23,778)
Other comprehensive income (loss)	(261)								(261)
Ending balance (in shares) at Sep. 30, 2020					95,516,373	11,374,019
Ending balance at Sep. 30, 2020	$ 535,120				$ 1	$ 1	$ 777,231		$ 124	$ (242,237)

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income (loss)	$ (50,228,000)	$ (37,477,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	14,411,000	11,693,000
Amortization of deferred rent	2,941,000	5,181,000
Amortization of debt issuance costs	58,000	1,884,000
Amortization of deferred contract costs	2,375,000	1,690,000
Stock-based compensation	34,752,000	7,550,000
Provision for doubtful accounts	1,212,000	344,000
Change in fair value of preferred stock warrant liabilities	0	2,404,000
Other adjustments	207,000	(502,000)
Interest paid on capital leases	(454,000)	(269,000)
Loss (gain) on disposals of property and equipment	(133,000)	43,000
Changes in operating assets and liabilities:
Accounts receivable	(6,669,000)	(9,520,000)
Prepaid expenses and other current assets	(3,778,000)	(5,811,000)
Other assets	(7,410,000)	(6,468,000)
Accounts payable	7,046,000	4,579,000
Accrued expenses	17,224,000	(2,703,000)
Other liabilities	(321,000)	(861,000)
Net cash provided by (used in) operating activities	11,233,000	(28,243,000)
Cash flows from investing activities:
Purchases of marketable securities	(204,361,000)	(177,525,000)
Sales of marketable securities	143,241,000	3,578,000
Maturities of marketable securities	83,718,000	68,044,000
Proceeds from sale of property and equipment	150,000	0
Purchases of property and equipment	(24,443,000)	(10,400,000)
Capitalized internal-use software	(4,082,000)	(3,218,000)
Purchases of intangible assets	(1,811,000)	(636,000)
Net cash used in investing activities	(7,588,000)	(120,157,000)
Cash flows from financing activities:
Proceeds from initial public offering, net of underwriting fees	0	192,510,000
Proceeds from follow-on public offering, net of underwriting fees	274,896,000	0
Repayments of notes payable	0	(27,488,000)
Repayments of capital leases	(3,060,000)	(905,000)
Proceeds from employee stock purchase plan	6,206,000	3,131,000
Proceeds from exercise of vested stock options	12,953,000	2,828,000
Proceeds from early exercise of stock options	0	520,000
Proceeds from payment of stockholder note	0	74,000
Net cash provided by financing activities	290,320,000	166,218,000
Effects of exchange rate changes on cash, cash equivalents, and restricted cash	(139,000)	12,000
Net increase in cash, cash equivalents, and restricted cash	293,826,000	17,830,000
Cash, cash equivalents, and restricted cash at beginning of period	86,229,000	36,963,000
Cash, cash equivalents, and restricted cash at end of period	380,055,000	54,793,000
Supplemental disclosure of cash flow information:
Cash paid for interest	758,000	4,931,000
Cash paid for income taxes, net of refunds received	1,000,000	13,000
Property and equipment additions not yet paid in cash	9,613,000	7,702,000
Vesting of early-exercised stock options	401,000	465,000
Capital lease outstanding from current year addition	5,439,000	4,750,000
Change in other assets from change in accounting principle	0	5,727,000
Conversion of convertible preferred stock warrants to convertible common stock warrants	0	5,665,000
Cashless exercise of common stock warrants	1,557,000	1,036,000
Costs related to the initial public offering, accrued but not yet paid	0	1,148,000
Stock-based compensation capitalized to internal-use software	1,238,000	0
Reconciliation of cash, cash equivalents, and restricted cash as shown in the statements of cash flows
Total cash, cash equivalents, and restricted cash	380,055,000	54,793,000
IPO
Cash flows from financing activities:
Payments of costs related to public offerings	0	(4,452,000)
Secondary Public Offering
Cash flows from financing activities:
Payments of costs related to public offerings	$ (675,000)	$ 0

Nature of Business

Nature of Business	9 Months Ended
	Sep. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Nature of Business Fastly, Inc. has built an edge cloud platform that can process, serve, and secure its customer’s applications as close to their end users as possible. As of September 30, 2020, our edge network spans 72 Points-of-Presence ("POPs") across 55 markets around the world. We were incorporated in Delaware in 2011 and are headquartered in San Francisco, California. As used herein, "Fastly," "we," "our," "the Company," and similar terms include Fastly, Inc. and its subsidiaries, unless the context indicates otherwise. Stock Split On May 3, 2019, we implemented a 1-for-2 reverse stock split of our stock. All shares of common stock, stock-based instruments, and per-share data included in these financial statements give effect to the stock split and the changes in authorized shares have been adjusted retroactively for all periods presented. Initial Public Offering ("IPO") On May 21, 2019, we completed an IPO in which we sold 12,937,500 shares of our newly authorized Class A common stock, which included 1,687,500 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at the public offering price of $16.00 per share. We received net proceeds of $192.5 million, after deducting underwriting discounts and commissions, from sales of our shares in the IPO. The net proceeds include additional proceeds of $25.1 million, net of underwriters' discounts and commissions, from the exercise of the underwriters' option to purchase an additional 1,687,500 shares of our Class A common stock. Prior to the closing of the IPO, all shares of common stock then outstanding were reclassified as Class B common stock. Immediately upon the closing of the IPO, all shares of convertible preferred stock then outstanding were converted into 53,630,213 shares of Class B common stock on a one-to-one basis. Prior to the IPO, we had seven outstanding series of convertible preferred stock each with a par value of $0.00002 per share, convertible at the option of the holder, that was classified as temporary equity on our consolidated balance sheet. On May 17, 2019, immediately upon closing of the IPO, our convertible preferred stock was automatically converted to shares of our Class B common stock. As of both September 30, 2020 and December 31, 2019, we had no convertible preferred stock issued or outstanding. Follow-on Public Offering On May 26, 2020, we completed a follow-on public offering in which we sold 6,900,000 shares of Class A common stock, which included 900,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares, at the public offering price of $41.50 per share. We received net proceeds of $274.9 million, after deducting underwriting discounts and commissions, from sales of our shares in the public offering. Acquisition of Signal Sciences On August 27, 2020, we entered into an Agreement and Plan of Merger and Reorganization (the “Merger Agreement”) to acquire Signal Sciences. The acquisition closed on October 1, 2020 and as a result of the acquisition, Signal Sciences became a wholly owned subsidiary of Fastly, Inc. Please refer to Note 14 — Subsequent Events for details on the subsequent closing of the merger on October 1, 2020.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The interim unaudited condensed consolidated financial statements and accompanying notes have been prepared in accordance with United States generally accepted accounting principles ("U.S. GAAP") along with instructions to Form 10-Q and Article 10 of Securities and Exchange Commission ("SEC") Regulation S-X. Certain changes in presentation have been made to conform the prior period presentation to the current period reporting. We have made certain presentation changes to distinguish and disclose as a separate line item, the non-cash amortization expense of our deferred contract costs balance from other assets within operating cash flows in the Condensed Consolidated Statements of Cash Flows. Principles of Consolidation The accompanying interim condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Unaudited Interim Financial Statements The accompanying interim condensed consolidated balance sheet as of September 30, 2020, the related interim condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, and the condensed consolidated statements of convertible preferred stock and stockholders' equity (deficit) for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the related footnote disclosures are unaudited. The unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. GAAP. In management’s opinion, the unaudited financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments necessary for the fair presentation of our financial position as of September 30, 2020. The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results expected for the full fiscal year or any other periods. Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments, and assumptions that affect the reported amounts of assets, liabilities, revenue, costs and expenses, and related disclosures. Actual results and outcomes could differ significantly from our estimates, judgments, and assumptions. Significant estimates, judgments, and assumptions used in these financial statements include, but are not limited to, those related to revenue, accounts receivable and related reserves, useful lives and realizability of long-lived assets, income tax reserves, and accounting for stock-based compensation. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. The effects of material revisions in estimates are reflected in the condensed consolidated financial statements in the period of change and prospectively from the date of the change in estimate. The ongoing global COVID-19 pandemic has impacted many operational aspects of our business and may continue to do so in the future. We assessed the impact that COVID-19 had on our results of operations, including, but not limited to an assessment of our allowance for doubtful accounts, the carrying value of short-term and long-term investments, the carrying value of goodwill and other long-lived assets, and the impact to revenue recognition and cost of revenues. While the COVID-19 pandemic has not had a material adverse impact on our financial operations to date, the future impacts of the pandemic and any resulting economic impact are largely unknown and rapidly evolving. We will continue to actively monitor the impact that COVID-19 has on the results of our business operations, and may make decisions required by federal, state or local authorities, or that are determined to be in the best interests of our employees, customers, partners, suppliers and stockholders. As a result, our estimates and judgments may change materially as new events occur or additional information becomes available to us. Concentrations of Credit Risk Financial instruments that potentially subject us to significant concentration of credit risk consist primarily of cash, cash equivalents, marketable securities, and accounts receivable. The primary focus of our investment strategy is to preserve capital and meet liquidity requirements. Our investment policy addresses the level of credit exposure by limiting the concentration in any one corporate issuer or sector and establishing a minimum allowable credit rating. To manage the risk exposure, we invest cash equivalents and marketable securities in a variety of fixed income securities, including government and investment-grade debt securities and money market funds. We place our cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits, if any. Concentrations of credit risk with respect to accounts receivable are primarily limited to certain customers to which we make substantial sales. Our customer base consists of a large number of geographically dispersed customers diversified across several industries. To reduce risk, we routinely assess the financial strength of our customers. Based on such assessments, we believe that our accounts receivable credit risk exposure is limited. No customer accounted for more than 10% of revenue for both the three months ended September 30, 2020 and September 30, 2019. One customer accounted for 11% of revenue for the nine months ended September 30, 2020. No customer accounted for more than 10% of revenue for the nine months ended September 30, 2019. No customer accounted for more than 10% of the total accounts receivable balance as of September 30, 2020 and December 31, 2019. Significant Accounting Policies There have been no material changes to our significant accounting policies as compared to those described in “Note 2 – Summary of Significant Accounting Policies” of our Annual Report on Form 10-K for the fiscal year ended December 31, 2019. New Accounting Pronouncements to be Adopted We are currently an emerging growth company as defined in Jumpstart Our Business Startups Act of 2012 ("JOBS Act"). For as long as we continue to be an emerging growth company, we intend to take advantage of certain exemptions from various public company reporting requirements, including delaying adoption of new or revised accounting standards until those standards apply to private companies. Based on the market value of our common stock held by non-affiliates as of June 30, 2020, we will cease to be an emerging growth company as of December 31, 2020. Once we no longer qualify as an emerging growth company, we will no longer be permitted to use these reporting exemptions. In February 2016, the FASB issued new guidance, Accounting Standard Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which establishes the principles to report transparent and economically neutral information about the assets and liabilities that arise from leases. Accordingly, this new standard introduces a lessee model that brings most operating leases on the balance sheet and also aligns certain of the underlying principles of the new lessor model with those in the new revenue recognition standard. The standard is effective for public entities' interim and annual periods beginning after December 15, 2018. As we will cease to be an emerging growth company as of December 31, 2020, we expect to adopt the standard on December 31, 2020, presenting the initial application of ASC 842 beginning on January 1, 2020, in our annual financial statements included in our Form 10-K for year ended December 31, 2020. We are currently evaluating the impact of ASC 842 on our financial statements. We expect the adoption of ASC 842 to materially gross up our consolidated balance sheets due to the recognition of operating lease right-of-use assets and operating lease liabilities, relating to the discounted future lease payments associated with our office leases and colocation arrangements. We do not anticipate a material impact to our results of operations and our statements of cash flows. We intend to elect the modified transition method of adoption discussed in ASU 2018-11 and the package of practical expedients. We also intend to apply the short-term lease exception for all lease arrangements that exempts us from recognizing a right-of-use assets or lease liabilities for leases that, at the acquisition date, have a remaining lease term of 12 months or less. In June 2016, FASB issued new guidance, ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces a new methodology for accounting for credit losses on financial instruments, including available-for-sale debt securities. The guidance establishes a new “expected loss model” that requires entities to estimate current expected credit losses on financial instruments by using all practical and relevant information. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements and related disclosures. We expect to adopt the guidance prospectively and do not expect the adoption of this standard to have a material impact on our consolidated financial statements. The standard is effective for public entities' interim and annual periods beginning after December 15, 2018. As we will cease to be an emerging growth company as of December 31, 2020, we expect to adopt the standard on December 31, 2020, presenting the initial application of ASC 326 beginning on January 1, 2020, in our annual financial statements included in our Form 10-K for year ended December 31, 2020. In August 2018, the FASB issued Accounting Standards Update No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (ASC 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement ("ASU 2018-15"). This guidance provides that implementation costs be evaluated for capitalization using the same criteria as that used for internal-use software development costs, with amortization expense being recorded in the same income statement expense line as the hosted service costs and over the expected term of the hosting arrangement. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements and related disclosures. We do not expect the adoption of ASU 2018-15 to have a material impact on our consolidated financial statements. The standard is effective for public entities' interim and annual periods beginning after December 15, 2018. As we will cease to be an emerging growth company as of December 31, 2020, we expect to adopt the standard on December 31, 2020, presenting the initial application of ASC 350 beginning on January 1, 2020, in our annual financial statements included in our Form 10-K for year ended December 31, 2020.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Revenue recognition Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. We enter into contracts that can include various combinations of products and services, each of which are distinct and accounted for as separate performance obligations. Revenue is recognized net of any taxes collected from customers, which are subsequently remitted to governmental authorities. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in Topic 606. Our contracts with customers often include promises to transfer multiple products and services to a customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. For contracts with multiple performance obligations, we allocate the contract transaction price to each performance obligation using our estimate of the standalone selling price ("SSP") of each distinct good or service in the contract. Judgment is required to determine the SSP for each distinct performance obligation. We analyze separate sales of our products and services as a basis for estimating the SSP of our products and services. We then use that SSP as the basis for allocating the transaction price when our product and services are sold together in a contract with multiple performance obligations. In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions and other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we may use information, such geographic region and distribution channel, in determining the SSP. The transaction price in a contract is typically equal to the minimum commit price in the contract less any discounts provided. Because our typical contracts represent distinct services delivered over time with the same pattern of transfer to the customer, usage-based consideration primarily related to actual consumption over the minimum commit levels is allocated to the period to which it relates. The amount of consideration recognized for usage above the minimum commit price is limited to the amount we expect to be entitled to receive in exchange for providing services. We have elected to apply the practical expedient for estimating and disclosing the variable consideration when variable consideration is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct good or service that forms part of a single performance obligation from our remaining performance obligations under these contracts. Performance obligations represent stand-ready obligations that are satisfied over time as the customer simultaneously receives and consumes the benefits provided by us. These obligations can be content delivery, security, professional services, support, edge cloud platform services, and others. Accordingly, our revenue is recognized over time, consistent with the pattern of benefit provided to the customer over the term of the agreement. At times, customers may request changes that either amend, replace, or cancel existing contracts. Judgment is required to determine whether the specific facts and circumstances within the contracts should be accounted for as a separate contract or as a modification. Nature of products and services We primarily derive revenue from the sale of services to customers executing contracts in which the standard contract term is one year, although terms may vary by contract. Most of our contracts are non-cancelable over the contractual term. These contracts commit the customer to a minimum monthly level of usage and specify the rate at which the customer must pay for actual usage above the monthly minimum. Our revenue by geography is based on the billing address of the customer. Aside from the United States, one other country, Singapore, accounted for 11% of revenue for the nine months ended September 30, 2020. Aside from the United States, no other single country accounted for more than 10% of revenue for the three months ended September 30, 2020 and the three and nine months ended September 30, 2019. The following table presents our net revenue by geographic region: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) United States $ 49,140 $ 35,473 $ 136,194 $ 101,416 Asia Pacific 10,306 4,607 34,157 12,747 Europe 8,003 7,108 23,549 19,890 All other 3,189 2,609 14,325 7,473 Total revenue $ 70,638 $ 49,797 $ 208,225 $ 141,526 The majority of our revenue is derived from enterprise customers, which are defined as customers with revenue in excess of $100,000 over the previous 12-month period. The following table presents our net revenue for enterprise and non-enterprise customers: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) Enterprise customers $ 63,353 $ 42,765 $ 186,490 $ 121,230 Non-enterprise customers 7,285 7,032 21,735 20,296 Total revenue $ 70,638 $ 49,797 $ 208,225 $ 141,526 Contract balances The timing of revenue recognition may differ from the timing of invoicing to customers. We have an unconditional right to consideration when we invoice our customers and record a receivable. We record a contract asset when revenue is recognized prior to invoicing, or a contract liability (deferred revenue) when revenue is recognized subsequent to invoicing. Deferred revenue includes amounts billed to customers for which revenue has not been recognized and consists of the unearned portions of edge cloud platform usage. Our payment terms and conditions vary by contract type. Payment terms on invoiced amounts are typically 15 to 45 days. The following table presents our contract assets and contract liabilities as of September 30, 2020 and as of December 31, 2019: As of September 30, 2020 As of December 31, 2019 (in thousands) Contract assets $ 403 $ 271 Contract liabilities $ 42 $ 317 The following table presents the revenue recognized during the three and nine months ended September 30, 2020 and 2019 from amounts included in the contract liability at the beginning of the period: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) Revenue recognized in the period from: Amounts included in contract liability at the beginning of the period $ 37 $ 518 $ 310 $ 1,517 Remaining performance obligations As of September 30, 2020 and December 31, 2019, we had $100.0 million and $70.7 million, of remaining performance obligations, which includes deferred revenue and amounts that will be invoiced and recognized in future periods, respectively. We apply the practical expedient of ASC 606, which gives us the optional exemption from disclosing certain information about our remaining performance obligations for our service contracts for which the original contract duration is one year or less, such as the aggregate transaction price allocated to the performance obligations that are unsatisfied (or partially unsatisfied) as of the end of the reporting period. The typical contract term is one year, although terms may vary by contract. As of September 30, 2020, we expect to recognize 80% of this balance over the next 12 months and the remainder within the following year. Costs to obtain a contract We capitalize incremental costs associated with obtaining customer contracts, specifically for sales commissions. These costs are deferred on our Condensed Consolidated Balance Sheets and amortized over the expected period of benefit on a straight-line basis. Based on the nature of our unique technology and services, the rate at which we continually enhance and update our technology, and our historical customer retention, the expected period of benefit is determined to be approximately five years. Amortization is recorded within the sales and marketing line item on the accompanying Condensed Consolidated Statements of Operations. The incremental costs associated with obtaining customer contracts, the majority of which are deferred commissions, are included in other assets on the accompanying Condensed Consolidated Balance Sheets. As of September 30, 2020 and December 31, 2019, our costs to obtain contracts were as follows: As of September 30, 2020 As of December 31, 2019 (in thousands) Deferred contract costs $ 11,693 $ 6,804

Investments and Fair Value Meas

Investments and Fair Value Measurements	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Investments and Fair Value Measurements	Investments and Fair Value Measurements Our total cash, cash equivalents and marketable securities consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Cash and cash equivalents: Cash $ 273,734 $ 11,623 Money market funds 36,234 2,020 Commercial paper — 2,499 Total cash and cash equivalents $ 309,968 $ 16,142 Marketable securities: Corporate notes and bonds $ 14,391 $ 17,470 Commercial paper 17,464 5,481 U.S. Treasury securities 60,447 78,160 Asset-backed securities — 13,856 Total marketable securities $ 92,302 $ 114,967 Available-for-Sale Investments The following table summarizes adjusted cost, gross unrealized gains and losses, and fair value related to available-for-sale securities classified as marketable securities on the accompanying Condensed Consolidated Balance Sheets as of September 30, 2020 and December 31, 2019: As of September 30, 2020 Amortized Gross Gross Fair (in thousands) Corporate notes and bonds $ 14,348 $ 43 $ — $ 14,391 Commercial paper 17,464 — — 17,464 U.S. Treasury securities 60,253 194 — 60,447 Total available-for-sale investments $ 92,065 $ 237 $ — $ 92,302 As of December 31, 2019 Amortized Gross Gross Fair (in thousands) Corporate notes and bonds $ 17,462 $ 9 $ (1) $ 17,470 Commercial paper 5,481 — — 5,481 U.S. Treasury securities 78,075 85 — 78,160 Asset-backed securities 13,852 4 — 13,856 Total available-for-sale investments $ 114,870 $ 98 $ (1) $ 114,967 The majority of our securities classified as available-for-sale as of September 30, 2020 have contractual maturities of one year or less. Certain securities held and classified as available-for-sale as of September 30, 2020 have contractual maturities greater than one year; however, we do not intend to hold these securities to maturity. Consistent with our intentions to hold the securities for less than 12 months we classify all securities as short-term. As of December 31, 2019, all securities classified as available-for-sale had contractual maturities of one year or less. There were no securities in a continuous loss position for 12 months or longer as of September 30, 2020 and December 31, 2019. Investments are reviewed periodically to identify possible other-than-temporary impairments. No impairment loss has been recorded on the securities included in the tables above, as we believe that the decrease in fair value of these securities is temporary. Fair Value of Financial Instruments For certain of our financial instruments, including cash held in banks, accounts receivable, and accounts payable, the carrying amounts approximate fair value due to their short maturities, and are therefore excluded from the fair value tables below. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. There is a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1—Observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3—Unobservable inputs that are supported by little or no market activity, which require management judgment or estimation. We measure our cash equivalents, marketable securities, and restricted cash at fair value. We classify our cash equivalents, marketable securities and restricted cash within Level 1 or Level 2 because we value these investments using quoted market prices or alternative pricing sources and models utilizing market observable inputs. The fair value of our Level 1 financial assets is based on quoted market prices of the identical underlying security. The fair value of our Level 2 financial assets is based on inputs that are directly or indirectly observable in the market, including the readily available pricing sources for the identical underlying security that may not be actively traded. Financial assets and liabilities measured and recorded at fair value on a recurring basis consisted of the following types of instruments: As of September 30, 2020 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents: Money market funds $ 36,234 $ — $ — $ 36,234 Total cash equivalents 36,234 — — 36,234 Marketable securities: Corporate notes and bonds — 14,391 — 14,391 Commercial paper — 17,464 — 17,464 U.S. Treasury securities — 60,447 — 60,447 Asset-backed securities — — — — Total marketable securities — 92,302 — 92,302 Restricted cash: Money market funds 70,087 — — 70,087 Total restricted cash 70,087 — — 70,087 Total financial assets $ 106,321 $ 92,302 $ — $ 198,623 As of December 31, 2019 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents: Money market funds $ 2,020 $ — $ — $ 2,020 Commercial paper — 2,499 — 2,499 Total cash equivalents 2,020 2,499 — 4,519 Marketable securities: Corporate notes and bonds — 17,470 — 17,470 Commercial paper — 5,481 — 5,481 U.S. Treasury securities — 78,160 — 78,160 Asset-backed securities — 13,856 — 13,856 Total marketable securities — 114,967 — 114,967 Restricted cash: Money market funds 70,087 — — 70,087 Total restricted cash 70,087 — — 70,087 Total financial assets $ 72,107 $ 117,466 $ — $ 189,573 There were no transfers of assets and liabilities measured at fair value between Level 1 and Level 2, or between Level 2 and Level 3, during the three and nine months ended September 30, 2020 and 2019.

Balance Sheet Information

Balance Sheet Information	9 Months Ended
	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Information	Balance Sheet Information Property and equipment, net Property and equipment, net consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Computer and networking equipment $ 121,096 $ 89,830 Leasehold improvements 3,319 3,285 Furniture and fixtures 684 681 Office equipment 662 579 Internal-use software 19,221 13,901 Property and equipment, gross $ 144,982 $ 108,276 Accumulated depreciation and amortization (61,484) (48,239) Property and equipment, net $ 83,498 $ 60,037 Depreciation and amortization expense on property and equipment for the three months ended September 30, 2020 and 2019 was approximately $4.9 million and $4.0 million, respectively. Included in these amounts was amortization expense for capitalized internal-use software costs of approximately $0.5 million for both the three months ended September 30, 2020 and 2019. Depreciation and amortization expense on property and equipment for the nine months ended September 30, 2020 and 2019 was approximately $14.3 million and $11.6 million, respectively. Included in these amounts was amortization expense for capitalized internal-use software costs of approximately $1.7 million and $1.6 million for the nine months ended September 30, 2020 and 2019, respectively. During the three and nine months ended September 30, 2020, we recorded a gain on disposal of computer and networking equipment of $0.1 million. During the three and nine months ended September 30, 2019, we did not record a gain on disposal of computer and networking equipment. As of September 30, 2020 and December 31, 2019, the unamortized balance of capitalized internal-use software costs on our Condensed Consolidated Balance Sheets was approximately $12.1 million and $8.5 million, respectively. Accrued expenses Accrued expenses consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Accrued compensation and related benefits $ 21,362 $ 8,734 Sales and use tax payable 5,324 3,938 Accrued acquisition-related costs 4,436 — Accrued colocation and bandwidth costs 3,886 3,237 Other accrued liabilities 3,551 3,969 Total accrued expenses $ 38,559 $ 19,878 Other Current Liabilities Other current liabilities consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Liability for early-exercised stock options $ 257 $ 467 Deferred revenue 42 317 Accrued computer and networking equipment 8,977 7,060 Other current liabilities 279 325 Total other current liabilities $ 9,555 $ 8,169 Other Long-Term Liabilities Other long-term liabilities consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Deferred rent $ 3,731 $ 634 Other long-term liabilities 213 404 Total other long-term liabilities $ 3,944 $ 1,038

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The changes in the carrying amount of goodwill for the nine months ended September 30, 2020 are as follows: Nine months ended (in thousands) Balance as of December 31, 2019 $ 372 Foreign currency translation (10) Balance as of September 30, 2020 $ 362 As of September 30, 2020 and December 31, 2019, our intangible assets consisted of the following: As of September 30, 2020 As of December 31, 2019 Gross carrying value Accumulated amortization Net carrying value Gross carrying value Accumulated amortization Net carrying value (in thousands) Intangible assets: In-process research and development ("IPR&D") $ 368 $ — $ 368 $ — $ — $ — Internet protocol addresses 2,891 (506) 2,385 1,448 (362) 1,086 Domain name 39 — 39 39 — 39 Total intangible assets $ 3,298 $ (506) $ 2,792 $ 1,487 $ (362) $ 1,125 Our intangible assets are comprised of internet protocol address costs, domain name costs and IPR&D. Internet protocol addresses and Domain name intangible assets are subject to amortization. During the nine months ended September 30, 2020, we acquired certain IPR&D assets for $0.4 million, which are not subject to amortization. During the nine months ended September 30, 2020, we purchased additional internet protocol addresses and domain names for a gross carrying value of $1.4 million. We did not acquire internet protocol addresses and domain names during the three months ended September 30, 2020. During the three and nine months ended September 30, 2019, we purchased additional internet protocol addresses and domain names for a gross carrying value of $0.6 million and $0.1 million, respectively. The annual expected amortization expense of intangible assets subject to amortization as of September 30, 2020 is as follows: As of September 30, 2020 (in thousands) Remainder of 2020 $ 72 2021 298 2022 302 2023 302 2024 292 Thereafter 1,158 Total $ 2,424 We perform tests for impairment of goodwill and long-lived assets on an annual basis as of October 31 or more frequently if events or changes in circumstances indicate that our long-lived assets might be impaired. We did not record any impairment charges during both the three and nine months ended September 30, 2020 and 2019.

Debt Instruments

Debt Instruments	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt Instruments	Debt Instruments Capital Lease Agreement In June 2017, we entered into a Capital Lease Agreement with an equipment provider. The agreement provides for a bargain purchase price at the end of the term. The following table reflects the Capital Lease agreements under our single master Capital Lease agreement entered into in June 2017: Date of Signed Agreement Date of Commencement, per Signed Agreement Amount of Network Equipment (in millions) Annual Interest Rate Term of Agreement (in years) June 2017 June 2017 $ 5.0 5.24 % 4.0 March 2018 March 2018 $ 0.5 5.38 % 4.0 February 2019 February 2019 $ 2.9 5.38 % 3.0 March 2019 March 2019 $ 1.3 5.38 % 3.0 August 2019 August 2019 $ 1.3 6.33 % 3.0 November 2019 November 2019 $ 2.2 5.69 % 3.0 December 2019 December 2019 $ 1.0 5.42 % 3.0 January 2020 February 2020 $ 1.0 5.42 % 3.0 March 2020 April 2020 $ 2.3 5.42 % 3.0 June 2020 July 2020 $ 3.6 4.95 % 3.0 September 2020 October 2020 $ 1.3 4.95 % 3.0 September 2020 October 2020 $ 2.2 4.95 % 3.0 As of September 30, 2020 and December 31, 2019, $11.9 million and $9.5 million was outstanding under the Capital Lease Agreement, respectively. We recognize the amortization of the underlying capital lease assets as depreciation and amortization expense. Cash Collateralized Revolving Credit Agreement In November 2019, we entered into a Revolving Credit Agreement with Citibank, N.A (the "Lender") for an aggregate commitment amount of $70.0 million with a maturity date of November 3, 2022 (the "Revolver"). The amount of borrowings available under the Revolving Credit Agreement at any time are collateralized by our cash, which is classified as restricted cash on our balance sheets. With prior written notice to the Lender, we have the right, at any time prior to the Revolver's maturity date, without premium or penalty, to terminate or reduce the Revolver arrangement. In event of such termination, the aggregate principal of the then outstanding amounts, including any accrued interest to date, shall be repaid and the restrictions on the associated collateralized cash would be released. The interest rate associated with each advance under the Revolving Credit Agreement is equal to the sum of LIBOR for the applicable interest period plus 1.50% which is a per annum rate based on outstanding borrowings. As such, for the initial interest period ending in November 2020, the interest rate is set at 3.46%. The commitment fee is 0.20% per annum based on the average daily unused amount of the commitment amount. Interest payments on outstanding borrowings are due on the last day of each interest period and payments for the commitment fee are due at the end of each calendar quarter. As of both September 30, 2020 and December 31, 2019, the outstanding balance on the Revolving Credit Agreement was $20.3 million. On November 4, 2020, we notified the Lender that we are terminating the Revolving Credit Agreement in accordance with its terms. In connection with the termination of the Revolving Credit Agreement, we will repay the currently outstanding aggregate principal amount of $20.3 million, as well as any accrued interest, as of the termination date. The associated restrictions on the collateralized cash of $70.1 million would be released, accordingly. We expect termination of the Revolving Credit Agreement and repayment to take place in November 2020. The following table reflects the carrying values of the debt and capital lease agreements as of September 30, 2020 and December 31, 2019: As of September 30, As of December 31, 2020 2019 (in thousands) Liability component: Principal amount—Cash Collateralized Revolving Credit Agreement $ 20,300 $ 20,300 Less: unamortized debt issuance costs (161) (219) Less: current portion of long-term debt — — Long-term debt, less current portion—Cash Collateralized Revolving Credit Agreement $ 20,139 $ 20,081 Principal amount—Capital Lease Agreement 11,928 9,549 Less: current portion of long-term debt (6,060) (4,472) Long-term debt, less current portion—Capital Lease Agreement $ 5,868 $ 5,077 Total long-term debt, less current portion $ 26,007 $ 25,158 Contractual future repayments for our debt and capital lease obligations as of September 30, 2020 are as follows: Principal Interest Total (in thousands) Remainder of 2020 $ 1,872 $ 926 $ 2,798 2021 6,921 1,350 8,271 2022 25,150 982 26,132 2023 1,795 30 1,825 2024 — — — Thereafter — — — Total $ 35,738 $ 3,288 $ 39,026 Interest expense related to debt for the three months ended September 30, 2020 and 2019 was $0.4 million and $0.6 million, respectively. Interest expense related to debt for the nine months ended September 30, 2020 and 2019 was $1.1 million and $4.8 million, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Lease Commitments We lease our facilities under non-cancelable operating leases. These operating leases expire at various dates through July 2027 and generally require the payment of real estate taxes, insurance, maintenance, and operating costs. There have been no material changes to our operating lease commitments as compared to those described in our most recently filed Annual Report on Form 10-K for the fiscal year ended December 31, 2019. We recognize rent expense on a straight-line basis over the lease period and have accrued for any rent expense incurred but not paid at each reporting period end. Rent expense for the three months ended September 30, 2020 and 2019 was $2.0 million and $1.8 million, respectively. Rent expense for the nine months ended September 30, 2020 and 2019 was $6.3 million and $4.9 million, respectively. During the three and nine months ended September 30, 2020 and 2019, we also had sublease agreements with tenants of various properties vacated by us. The amount earned from our sublease tenants was approximately $0.3 million and $0.3 million during the three months ended September 30, 2020 and 2019, respectively. The amount earned from our sublease tenants was approximately $0.9 million and $0.9 million during the nine months ended September 30, 2020 and 2019, respectively. Purchase Commitments As of September 30, 2020, we had long-term commitments for cost of revenue related agreements (i.e., bandwidth usage, colocation, peering and other managed services with various networks, internet service providers ("ISPs") and other third-party vendors). Our minimum future commitments related to cost of revenue related agreements as of September 30, 2020 were as follows: Cost of Revenue Commitments (in thousands) Remainder of 2020 $ 12,388 2021 35,411 2022 10,548 2023 3,141 2024 523 Thereafter 816 Total $ 62,827 We also have long-term commitments for various non-cancelable software as a service ("SaaS") agreements. There have been no material changes to our purchase commitments related to SaaS agreements as compared to those described in our most recently filed Annual Report on Form 10-K for the fiscal year ended December 31, 2019. Legal Matters On August 27, 2020, a purported securities class action lawsuit was filed in the United States District Court for the Northern District of California, captioned Marcos Betancourt v. Fastly, Inc., et al. (Case No. 4:20-cv-06024-PJH) naming as defendants us and certain of our officers. On September 15, 2020, a substantively identical complaint was filed against the same defendants in the same court, captioned Rami Habib v. Fastly, Inc., et al. (Case No. 4:20-cv-06454-JST). The complaints assert that all defendants violated Section 10(b) of the Exchange Act and SEC Rule 10b-5 by making materially false or misleading statements between May 6, 2020 and August 5, 2020 regarding our business and financials, while not disclosing the identity of one of its largest customers. The plaintiffs also allege that certain of our officers violated Section 20(a) of the Exchange Act. On September 27, 2020, the court consolidated the two cases into one putative class action, captioned In re Fastly, Inc. Securities Litigation. Motions for lead plaintiff were filed on October 26, 2020 and the hearing on the lead plaintiff motion is set for December 2, 2020. It is possible that additional lawsuits will be filed, or allegations made by stockholders, regarding these same or other matters and also naming as defendants the Company and our officers and directors. We are also party to various disputes that management considers routine and incidental to our business. Management does not expect the results of any of these routine actions to have a material effect on our business, results of operations, financial conditions, or cash flows. The pending lawsuits and any other related lawsuits are subject to inherent uncertainties, and the actual defense and disposition costs will depend upon many unknown factors. The outcome of the pending lawsuits and any other related lawsuits is necessarily uncertain. We could be forced to expend significant resources in the defense of the pending lawsuits and any additional lawsuits, and we may not prevail. In addition, we may incur substantial legal fees and costs in connection with such lawsuits. We currently are not able to estimate the possible cost to us from these matters, as the pending lawsuits are currently at an early stage, and we cannot be certain how long it may take to resolve the pending lawsuits or the possible amount of any damages that we may be required to pay. Such amounts could be material to our financial statements if we do not prevail in the defense against the pending lawsuits and any other related lawsuits, or even if we do prevail. As of September 30, 2020, we have not accrued for any loss contingencies on the above mentioned lawsuit as we do not believe an outcome resulting in a loss is probable. We will accrue for loss contingencies if it becomes both probable that we will incur a loss and if we can reasonably estimate the amount or range of the loss. Indemnification We enter into standard indemnification agreements in the ordinary course of business. Pursuant to these agreements, we agree to indemnify, hold harmless, and reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally our business partners or customers, in connection with our provision of its services. Generally, these obligations are limited to claims relating to infringement of a patent, copyright, or other intellectual property right, breach of the Company’s security or data protection obligations, or the Company’s negligence, willful misconduct, or violation of law. Subject to applicable statutes of limitation, the term of these indemnification agreements is generally for the duration of the agreement. The maximum potential amount of future payments we could be required to make under these indemnification agreements is unlimited; however, we carry insurance that covers certain third-party claims relating to our services and could limit our exposure in that respect. We have agreed to indemnify each of our officers and directors during his or her lifetime for certain events or occurrences that happen by reason of the fact that the officer or director is, was, or has agreed to serve as an officer or director of the Company. We have director and officer insurance policies that may limit our exposure and may enable us to recover a portion of certain future amounts paid. To date, we have not encountered material costs as a result of such indemnification obligations and have not accrued any related liabilities in our financial statements. In assessing whether to establish an accrual, we consider such factors as the degree of probability of an unfavorable outcome and the ability to make a reasonable estimate of the amount of loss.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders' Equity Common Stock Our Amended and Restated Certificate of Incorporation, as amended and restated in May 2019, authorizes the issuance of 1.0 billion shares of Class A common stock and 94.1 million shares of Class B common stock, and 10.0 million shares of preferred stock, each at a par value per share of $0.00002. Holders of Class A common stock are entitled to one vote per share and holders of Class B common stock are entitled to 10 votes per share. Preferred stockholders, do not have voting rights. As of September 30, 2020 and December 31, 2019, 95.5 million and 61.0 million shares of Class A common stock were issued and outstanding, respectively. As of September 30, 2020 and December 31, 2019, 11.4 million and 33.9 million shares of Class B common stock were issued and outstanding, respectively. As of both September 30, 2020 and December 31, 2019, no shares of preferred stock were issued and outstanding. Equity Incentive Plans In March 2011, our stockholders approved our 2011 Equity Incentive Plan ("2011 Plan") which allows for the issuance of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, and restricted stock unit awards ("RSUs") to employees, directors, and consultants of the Company. Options granted under our 2011 Plan are exercisable for shares of our Class B common stock. As of both September 30, 2020 and December 31, 2019, there were 23.6 million shares of Class B common stock reserved for issuance pursuant to outstanding stock options under the 2011 Plan. As of September 30, 2020 and December 31, 2019, there were no shares of Class B common stock available for issuance for future grants under the 2011 Plan. In May 2019, in conjunction with our IPO, our Board and stockholders approved our 2019 Equity Incentive Plan (the "2019 Plan") which allows for the issuance of incentive stock options, non-statutory stock options, stock appreciation rights, RSUs, performance-based stock awards, and other forms of equity compensation, which are collectively referred to as stock awards. Additionally, the 2019 Plan provides for the grant of performance cash awards. Options are exercisable for shares of our Class A common stock. No further awards will be issued under the 2011 Plan. As of September 30, 2020 and December 31, 2019, there were 19.2 million shares and 14.4 million shares of Class A common stock reserved for issuance under the 2019 Plan, respectively. As of September 30, 2020 and December 31, 2019, there were 13.4 million and 12.4 million Class A common stock available for issuance under the 2019 Plan, respectively. In May 2019, in conjunction with our IPO, our Board and stockholders approved the Employee Stock Purchase Plan ("ESPP"). The ESPP allows eligible employees to purchase shares of our Class A common stock through payroll deductions of up to 15% of their eligible compensation, subject to a maximum of $25,000 per calendar year. As of September 30, 2020 and December 31, 2019, there were 3.5 million shares and 2.5 million shares of Class A common stock reserved for issuance under the ESPP, respectively. As of September 30, 2020 and December 31, 2019, there were 2.9 million shares and 2.2 million shares of Class A common stock available for future issuance under the ESPP, respectively. Stock Options Options granted under the 2011 Plan are exercisable for Class B common stock and generally expire within 10 years from the date of grant and generally vest over four years, at the rate of 25% on the first anniversary of the date of grant and ratably on a monthly basis over the remaining 36-month period thereafter based on continued service. Options granted under the 2019 Plan are exercisable for Class A common stock and generally expire within 10 years from the date of grant and generally vest over four years, at the rate of 25% on the first anniversary of the date of grant and ratably on a monthly basis over the remaining 36-month period thereafter based on continued service. Forfeitures are recognized as they occur. The following table summarizes stock option activity during the nine months ended September 30, 2020: Shares Weighted- Weighted- Aggregate (in thousands) (in years) (in thousands) Outstanding at December 31, 2019 11,269 $ 4.68 7.3 $ 173,471 Granted — — Exercised (3,803) 3.36 Cancelled/forfeited (176) 8.80 Outstanding at September 30, 2020 7,290 $ 5.28 6.8 $ 644,502 Vested and exercisable at September 30, 2020 4,296 $ 3.41 5.9 $ 387,817 The total pre-tax intrinsic value of options exercised during the nine months ended September 30, 2020 and 2019 was $157.9 million and $12.7 million, respectively. The total grant date fair value of employee options vested for the nine months ended September 30, 2020 and 2019 was $6.5 million and $4.4 million, respectively. The weighted average grant-date fair value for options granted to employees during the nine months ended September 30, 2019 was $6.05. There were no options granted during the nine months ended September 30, 2020. We estimate the fair value of stock options on the date of grant using the Black-Scholes option-pricing model. Each of the Black-Scholes inputs is subjective and generally requires significant judgments to determine. We estimated the fair value of stock option awards using the Black-Scholes option pricing model with the following weighted-average assumptions: Nine months ended September 30, 2020 2019 Fair value of common stock N/A $12.38 Expected term (in years) N/A 6.48 Risk-free interest rate N/A 2.30% Expected volatility N/A 40.0% Dividend yield N/A —% During the three months ended September 30, 2020 and 2019, we recorded stock-based compensation expense from stock options of approximately $1.8 million and $2.1 million, respectively. During the nine months ended September 30, 2020 and 2019, we recorded stock-based compensation expense from stock options of approximately $5.7 million and $5.4 million, respectively. As of September 30, 2020, total unrecognized stock-based compensation cost related to outstanding unvested stock options that are expected to vest was $12.4 million. This unrecognized stock-based compensation cost is expected to be recognized over a weighted-average period of approximately 2.13 years. Early Exercise of Stock Options Certain stock options granted by the Company are exercisable at the date of grant, with unvested shares subject to repurchase by the Company in the event of voluntary or involuntary termination of employment of the stockholder. Such exercises are recorded as a liability on the accompanying Condensed Consolidated Balance Sheets and reclassified into equity as the options vest. As of September 30, 2020 and December 31, 2019, a total of 105,847 and 199,895 shares of Class B Common Stock were subject to repurchase by the Company at the lower of (i) the fair market value of such shares on the date of repurchase, or (ii) the original exercise price of such shares. The corresponding exercise value of approximately $0.5 million and $0.9 million as of September 30, 2020 and December 31, 2019, respectively, is recorded in other current liabilities and other liabilities on the accompanying Condensed Consolidated Balance Sheets. The activity of non-vested shares as a result of early exercise of options granted to employees and non-employees, is as follows: Nine months ended September 30, 2020 (in thousands) Beginning balance as of December 31, 2019 200 Early exercise of options — Vested (94) Repurchased Ending balance as of September 30, 2020 106 Restricted Stock Units ("RSUs") We began granting RSUs under the 2019 Plan during the fiscal year ended December 31, 2019. The fair value of RSUs is based on the grant date fair value and is expensed on a straight-line basis over the applicable vesting period. RSUs typically vest over four years, at the rate of 25% on the first anniversary of the vest date and ratably on a quarterly basis over the remaining 36-month period thereafter, based on continued service. Forfeitures are recognized as they occur. The following table summarizes RSU activity during the nine months ended September 30, 2020: Shares Weighted-Average (in thousands) RSUs outstanding as of December 31, 2019 1,641 $ 20.07 Granted 3,726 24.62 Vested (905) 21.52 Cancelled/forfeited (108) 21.53 RSUs outstanding as of September 30, 2020 4,354 $ 23.67 During the three and nine months ended September 30, 2020, we recognized stock-based compensation expense related to RSUs of $10.6 million and $28.0 million, respectively. During the three and nine months ended September 30, 2019, we recognized stock-based compensation expense related to RSUs of $0.7 million. During the nine months ended September 30, 2020, the Company modified the terms of its RSUs awarded to an employee to allow for the remainder unvested awards to be fully vested upon their change in employment status. As a result, the Company recorded incremental stock-based compensation expense in relation to the modification of $4.8 million for the nine months ended September 30, 2020. Included in this expense, is the incremental fair value resulting from the modifications of the RSUs of $0.1 million. During the three months ended September 30, 2020, there were no equity award modifications that resulted in a material incremental expense recorded. During both the three and nine months ended September 30, 2019, there were no equity award modifications that resulted in incremental expense recorded. As of September 30, 2020, total unrecognized stock-based compensation cost related to non-vested RSUs was $92.4 million. This unrecognized stock-based compensation cost is expected to be recognized over a weighted-average period of approximately 3.34 years. Performance-Based Restricted Stock Units ("PSUs") In March 2020, the Company granted a maximum total of 87,918 shares of PSUs to certain employees of the company, pursuant to the Company’s 2019 Equity Incentive Plan. The PSUs granted reflect a maximum of 200% of target performance and represent the right of the employees to be issued on a future date, one (1) share of Class A common stock for each RSU received that will vest on the applicable vesting date. On November 2, 2020, the Compensation Committee of the Board of Directors set the performance conditions related to the previously granted PSUs. The performance conditions are based on the level of achievement of certain Company and individual targets related to Fastly's operating plan for the fiscal year 2020 ("2020 operating plan"). The PSUs will vest at 50% of the target if the Company achieves 90% performance under the 2020 operating plan, 100% of the target if the Company achieves 100% performance under the 2020 operating plan and 200% of the target if the Company achieves 110% performance or greater under the 2020 operating plan. These awards will be eligible to vest linearly within those parameters. Subject to employees’ continuous service with the Company through each vesting date, 25% of the number of RSUs credited to them upon certification of achievement will vest on February 15, 2021, May 15, 2021, August 15, 2021, and November 15, 2021, respectively. As of the nine months ended September 30, 2020, none of these performance conditions have been met. We expect to record stock-based compensation related to these PSUs once it is considered probable that the performance conditions set will be met. ESPP The ESPP allows eligible employees to purchase shares of our common stock through payroll deductions of up to 15% of their eligible compensation. The ESPP provides for six-month offering periods, commencing in May and November of each year. At the end of each offering period employees are able to purchase shares at 85% of the lower of the fair market value of our Class A common stock on the first trading day of the offering period or on the date of purchase. We estimate the fair value of shares to be issued under the ESPP on the first day of the offering period using the Black-Scholes valuation model. The inputs to the Black-Scholes option pricing model are our stock price on the first date of the offering period, the risk-free interest rate, the estimated volatility of our stock price over the term of the offering period, the expected term of the offering period and the expected dividend rate. Stock-based compensation expense related to the ESPP is recognized on a straight-line basis over the offering period. Forfeitures are recognized as they occur. We estimated the fair value of shares granted under the ESPP on the first date of the offering period using the Black-Scholes option pricing model with the following assumptions: Nine months ended September 30, 2020 2019 Fair value of common stock $14.09 $6.92 Expected term (in years) 0.5 0.5 Risk-free interest rate 0.85% 2.35% Expected volatility 52.0% 36.4% Dividend yield —% —% During the three and nine months ended September 30, 2020, we withheld $2.0 million and $6.1 million in contributions from employees, respectively, and recognized $0.4 million and $2.3 million in stock-based compensation expense related to the ESPP, respectively. During the three and nine months ended September 30, 2019, we withheld $2.3 million and $3.1 million in contributions from employees, respectively, and recognized $1.1 million and $1.5 million in stock-based compensation expense related to the ESPP, respectively. During the nine months ended September 30, 2020, 0.2 million shares of our Class A common stock was purchased under the offering period that commenced on November 21, 2019. No common stock was issued under the ESPP in the three months ended September 30, 2020, nor in the three and nine months ended September 30, 2019. Stock-based Compensation Expense The following table summarizes the components of total stock-based compensation expense included in the accompanying Condensed Consolidated Statements of Operations: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) Stock-based compensation expense by caption: Cost of revenue $ 929 $ 438 $ 2,634 $ 875 Research and development 4,371 968 10,095 2,114 Sales and marketing 3,194 929 11,753 1,894 General and administrative 3,648 1,505 10,270 2,667 Total $ 12,142 $ 3,840 $ 34,752 $ 7,550 For the three and nine months ended September 30, 2020, we capitalized $0.6 million and $1.2 million of stock-based compensation expense. For the three and nine months ended September 30, 2019, we did not capitalize any stock-based compensation expense. Common Stock Warrant Liabilities Prior to the IPO, we issued convertible preferred stock warrants in conjunction with the issuances of debt. We recorded these warrants to purchase convertible preferred stock as a liability on the consolidated balance sheets at fair value upon issuance as the warrants were exercisable for contingently redeemable preferred stock which was classified outside of stockholders' equity (deficit). The liability associated with these warrants were subject to remeasurement at each balance sheet date, with changes in fair value recorded in the consolidated statement of operations and comprehensive loss as other expense, net. On May 17, 2019, immediately upon closing of the IPO, our warrants to purchase convertible preferred stock were automatically converted to warrants to purchase an equal number of shares of our Class B common stock. As a result, the warrant was remeasured a final time, immediately prior to the closing of the IPO, and reclassified to additional paid-in capital within stockholders' equity. Changes in the fair value were recorded within other expense, net on the consolidated statement of operations. As of December 31, 2019, the warrants were classified and recorded as additional paid-in capital on the condensed consolidated balance sheets. In the nine months ended September 30, 2020, certain Class B common stock warrants related to the previously outstanding subordinated debt and loan agreements were exercised under the cashless exercise method pursuant to the corresponding warrant agreements. As a result of such exercises, we issued 144,635 shares of our Class B common stock. No Class B common stock warrants were exercised under the cashless exercise method pursuant to the corresponding warrant agreements during the three months ended September 30, 2020. In the three months ended September 30, 2019, certain Class B common stock warrants related to the Credit Facility were exercised under the cashless exercise method pursuant to the corresponding warrant agreement. In the nine months ended September 30, 2019, certain Class B common stock warrants related to the Credit Facility, certain class B common stock warrants related to the Facility, certain Class B common stock warrants related to the Prior Loan Agreement, the Class B common stock warrants related to a previously outstanding term loan agreement, certain Class B common stock warrants related to the Mezzanine Loan and Security Agreement were exercised under the cashless exercise method pursuant to the corresponding warrant agreements. As a result of such exercises, we issued 51,722 and 224,102 shares of our Class B common stock in the three and nine months ended September 30, 2019.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders We compute net loss per share using the two-class method required for multiple classes of common stock and participating securities. Class A and Class B common stock are the only outstanding equity of the Company. The rights of the holders of the Class A common stock and Class B common stock are identical, except with respect to voting and conversion. Each share of Class A common stock is entitled to one vote per share and each share of Class B common stock is entitled to 10 votes per share. Shares of Class B common stock may be converted into Class A common stock at any time at the option of the stockholder on a one-for-one basis, and are automatically converted into Class A common stock upon sale or transfer, subject to certain limited exceptions. Shares of Class A common stock are not convertible. Accordingly, the Class A common stock and Class B common stock share equally in our net losses. Prior to the IPO, our participating securities also included convertible preferred stock. The holders of convertible preferred stock did not have a contractual obligation to share in our losses, and as a result, net losses were not allocated to these participating securities. The following table sets forth the calculation of basic and diluted net loss per share attributable to common stockholders during the periods presented. The shares issued in the IPO, the shares issued pursuant to the exercise by the underwriters of an option to purchase additional shares, and the shares of Class A and Class B common stock issued upon conversion of the outstanding shares of convertible preferred stock in the IPO are included in the table below, weighted for the period outstanding: Three months ended September 30, 2020 2019 Class A (1) Class B (2) Class A (1) Class B (2) (in thousands, except per share amounts) Net loss attributable to common stockholders $ (20,763) $ (3,015) (1,703) $ (10,460) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 92,510 13,432 13,054 80,186 Net loss per share attributable to common stockholders, basic and diluted $ (0.22) $ (0.22) $ (0.13) $ (0.13) Nine months ended September 30, 2020 2019 Class A (1) Class B (2) Class A (1) Class B (2) (in thousands, except per share amounts) Net loss attributable to common stockholders $ (39,670) $ (10,558) $ (4,116) $ (33,361) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 79,307 21,106 6,555 53,124 Net loss per share attributable to common stockholders, basic and diluted $ (0.50) $ (0.50) $ (0.63) $ (0.63) __________ (1) Class A common stock includes the issuance of 12.9 million shares of Class A common stock issued by us in connection with our IPO and shares issued upon the exercise of options and vesting of RSUs subsequent to our IPO. It also includes the shares issued in connection with our follow-on offering on May 26, 2020. (2) Class B common stock includes, for all periods presented, the conversion of all of our preferred stock into an aggregate of 53.6 million shares of our Class B common stock upon closing of the IPO. Since we were in a loss position for the periods presented, basic net loss per share is the same as diluted net loss per share, as the inclusion of all potential common shares outstanding would have been anti-dilutive. The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive are as follows: Number of Shares As of September 30, 2020 2019 (in thousands) Stock options 7,290 12,459 RSUs 4,354 864 Early exercised stock options 106 240 Common stock warrants — 183 Shares issuable pursuant to the ESPP 90 230 PSUs 88 — Total 11,928 13,976

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our provision for income taxes for interim periods is determined using an estimate of our annual effective tax rate, adjusted for discrete items, if any, that arise during the period. Each quarter, we update our estimate of the annual effective tax rate, and if the estimated annual effective tax rate changes, we make a cumulative adjustment in such period. In the three months ended September 30, 2020 and 2019, we recorded income tax expenses of $0.3 million and less than $0.1 million, respectively. In the nine months ended September 30, 2020 and 2019, we recorded income tax expenses of $1.1 million and $0.2 million, respectively. We continue to maintain a full valuation allowance on our U.S. Federal and state net deferred tax assets. The tax expense for the three and nine months ended September 30, 2020 and 2019 was primarily due to foreign and state income tax expense. On March 27, 2020, the “Coronavirus Aid, Relief and Economic Security (CARES) Act” was signed into law (the "CARES Act"). The CARES Act includes provisions relating to refundable payroll tax credits, deferment of the employer portion of certain payroll taxes, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. Since the second quarter of 2020, we utilized the provision to defer payment of certain of our payroll taxes. Any deferred payments will be accrued for as a liability and included in our condensed consolidated balance sheet for the applicable period. As of September 30, 2020, we have accrued for $2.7 million in payroll tax deferrals related to the CARES Act. We are continuing to evaluate the other provisions of the CARES Act, but do not expect them to have a material impact on our consolidated financial statements.

Information About Revenue and G

Information About Revenue and Geographic Areas	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Information About Revenue and Geographic Areas	Information About Revenue and Geographic AreasWe consider operating segments to be components of the Company in which separate financial information is available and is evaluated regularly by our Chief Operating Decision Maker ("CODM") in deciding how to allocate resources and in assessing performance. Our CODM is the Chief Executive Officer ("CEO"). The CEO reviews financial information presented on a consolidated basis, accompanied by information about revenue, customer size, and industry vertical for purposes of allocating resources and evaluating financial performance. We have determined that we operate under one business unit with no segment managers who are held accountable for operations, operating results, or plans for levels or components below the consolidated unit level. Accordingly, we have determined that we have a single reporting segment and operating unit structure. Revenue Revenue by geography is based on the billing address of the customer. Refer to Note 3, "Revenue" for more information on net revenue by geographic region. Long-Lived Assets The following table presents long-lived assets by geographic region: As of September 30, As of December 31, 2020 2019 (in thousands) United States $ 54,734 $ 40,747 All other countries 28,764 19,290 Total long-lived assets $ 83,498 $ 60,037

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionsIn July 2016, a stockholder borrowed approximately $0.1 million to exercise stock options for 53,125 shares of common stock pursuant to a promissory note from the stockholder. The note bears interest at a rate of 1.77%. In June 2019, the promissory note was repaid in full. Prior to repayment, for the purposes of the financial statements, the shares were not reported as exercised, issued, or outstanding. This stockholder is not one of our executive officers or directors. There were no outstanding balances as of both September 30, 2020 and December 31, 2019.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Event	Subsequent Events Signal Sciences Acquisition On August 27, 2020, we entered into the Merger Agreement to acquire Signal Sciences. We completed this acquisition on October 1, 2020. As a result of the acquisition, we acquired 100% of the voting rights of Signal Sciences and it is now our wholly-owned subsidiary. The acquisition is expected to expand our security portfolio and bolster our existing security offerings with our web application and API protection solutions. Under the terms of the Merger Agreement, we acquired Signal Sciences for an aggregate purchase price of $775.0 million, consisting of approximately $200.0 million in cash and the balance in 6,367,709 shares of our Class A Common Stock, with a par value $0.00002 per share; provided, that (a) unvested options to purchase Signal Sciences capital stock held by employees of Signal Sciences, who remained or became employees of Fastly or any of our subsidiaries following the acquisition, were assumed by us and (b) all unvested options to purchase stock held by any former employees of Signal Sciences were cancelled for no consideration. In October 2020, we assumed the aforementioned unvested options to purchase Signal Sciences capital stock held by employees of Signal Sciences who remained or became employees of Fastly or any of our subsidiaries following the acquisition. Options to purchase 251,754 shares of our Class A common stock are outstanding in connection with the assumption of these awards. In addition, we have established a retention pool in an aggregate amount of $50.0 million in the form of restricted stock units covering shares of our Class A Common Stock that will be granted to certain former Signal Sciences employees in accordance with the terms of the Merger Agreement. Due to the limited time since the acquisition date and limitations on access to Signal Sciences information prior to the acquisition date, the initial accounting for the business combination has not been completed at this time. As a result, we are

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The interim unaudited condensed consolidated financial statements and accompanying notes have been prepared in accordance with United States generally accepted accounting principles ("U.S. GAAP") along with instructions to Form 10-Q and Article 10 of Securities and Exchange Commission ("SEC") Regulation S-X. Certain changes in presentation have been made to conform the prior period presentation to the current period reporting. We have made certain presentation changes to distinguish and disclose as a separate line item, the non-cash amortization
Principles of Consolidation and Unaudited Interim Financial Statements	Principles of Consolidation The accompanying interim condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions and balances have been eliminated in consolidation. Unaudited Interim Financial Statements The accompanying interim condensed consolidated balance sheet as of September 30, 2020, the related interim condensed consolidated statements of operations, the condensed consolidated statements of comprehensive loss, and the condensed consolidated statements of convertible preferred stock and stockholders' equity (deficit) for the three and nine months ended September 30, 2020 and 2019, the condensed consolidated statements of cash flows for the nine months ended September 30, 2020 and 2019, and the related footnote disclosures are unaudited. The unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. GAAP. In management’s opinion, the unaudited financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments necessary for the fair presentation of our financial position as of September 30, 2020. The results for the three and nine months ended September 30, 2020 are not necessarily indicative of the results expected for the full fiscal year or any other periods.
Use of Estimates	Use of Estimates The preparation of our condensed consolidated financial statements requires us to make estimates, judgments, and assumptions that affect the reported amounts of assets, liabilities, revenue, costs and expenses, and related disclosures. Actual results and outcomes could differ significantly from our estimates, judgments, and assumptions. Significant estimates, judgments, and assumptions used in these financial statements include, but are not limited to, those related to revenue, accounts receivable and related reserves, useful lives and realizability of long-lived assets, income tax reserves, and accounting for stock-based compensation. Estimates are periodically reviewed in light of changes in circumstances, facts, and experience. The effects of material revisions in estimates are reflected in the condensed consolidated financial statements in the period of change and prospectively from the date of the change in estimate. The ongoing global COVID-19 pandemic has impacted many operational aspects of our business and may continue to do so in the future. We assessed the impact that COVID-19 had on our results of operations, including, but not limited to an assessment of our allowance for doubtful accounts, the carrying value of short-term and long-term investments, the carrying value of goodwill and other long-lived assets, and the impact to revenue recognition and cost of revenues. While the COVID-19 pandemic has not had a material adverse impact on our financial operations to date, the future impacts of the pandemic and any resulting economic impact are largely unknown and rapidly evolving. We will continue to actively monitor the impact that COVID-19 has on the results of our business operations, and may make decisions required by federal, state or local authorities, or that are determined to be in the best interests of our employees, customers, partners, suppliers and stockholders. As a result, our estimates and judgments may change materially as new events occur or additional information becomes available to us.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject us to significant concentration of credit risk consist primarily of cash, cash equivalents, marketable securities, and accounts receivable. The primary focus of our investment strategy is to preserve capital and meet liquidity requirements. Our investment policy addresses the level of credit exposure by limiting the concentration in any one corporate issuer or sector and establishing a minimum allowable credit rating. To manage the risk exposure, we invest cash equivalents and marketable securities in a variety of fixed income securities, including government and investment-grade debt securities and money market funds. We place our cash primarily in checking and money market accounts with reputable financial institutions. Deposits held with these financial institutions may exceed the amount of insurance provided on such deposits, if any. Concentrations of credit risk with respect to accounts receivable are primarily limited to certain customers to which we make substantial sales. Our customer base consists of a large number of geographically dispersed customers diversified across several industries. To reduce risk, we routinely assess the financial strength of our customers. Based on such assessments, we believe that our accounts receivable credit risk exposure is limited.
Recently Adopted and Issued Accounting Pronouncements	New Accounting Pronouncements to be Adopted We are currently an emerging growth company as defined in Jumpstart Our Business Startups Act of 2012 ("JOBS Act"). For as long as we continue to be an emerging growth company, we intend to take advantage of certain exemptions from various public company reporting requirements, including delaying adoption of new or revised accounting standards until those standards apply to private companies. Based on the market value of our common stock held by non-affiliates as of June 30, 2020, we will cease to be an emerging growth company as of December 31, 2020. Once we no longer qualify as an emerging growth company, we will no longer be permitted to use these reporting exemptions. In February 2016, the FASB issued new guidance, Accounting Standard Update No. 2016-02, Leases (Topic 842) ("ASU 2016-02"), which establishes the principles to report transparent and economically neutral information about the assets and liabilities that arise from leases. Accordingly, this new standard introduces a lessee model that brings most operating leases on the balance sheet and also aligns certain of the underlying principles of the new lessor model with those in the new revenue recognition standard. The standard is effective for public entities' interim and annual periods beginning after December 15, 2018. As we will cease to be an emerging growth company as of December 31, 2020, we expect to adopt the standard on December 31, 2020, presenting the initial application of ASC 842 beginning on January 1, 2020, in our annual financial statements included in our Form 10-K for year ended December 31, 2020. We are currently evaluating the impact of ASC 842 on our financial statements. We expect the adoption of ASC 842 to materially gross up our consolidated balance sheets due to the recognition of operating lease right-of-use assets and operating lease liabilities, relating to the discounted future lease payments associated with our office leases and colocation arrangements. We do not anticipate a material impact to our results of operations and our statements of cash flows. We intend to elect the modified transition method of adoption discussed in ASU 2018-11 and the package of practical expedients. We also intend to apply the short-term lease exception for all lease arrangements that exempts us from recognizing a right-of-use assets or lease liabilities for leases that, at the acquisition date, have a remaining lease term of 12 months or less. In June 2016, FASB issued new guidance, ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which introduces a new methodology for accounting for credit losses on financial instruments, including available-for-sale debt securities. The guidance establishes a new “expected loss model” that requires entities to estimate current expected credit losses on financial instruments by using all practical and relevant information. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements and related disclosures. We expect to adopt the guidance prospectively and do not expect the adoption of this standard to have a material impact on our consolidated financial statements. The standard is effective for public entities' interim and annual periods beginning after December 15, 2018. As we will cease to be an emerging growth company as of December 31, 2020, we expect to adopt the standard on December 31, 2020, presenting the initial application of ASC 326 beginning on January 1, 2020, in our annual financial statements included in our Form 10-K for year ended December 31, 2020. In August 2018, the FASB issued Accounting Standards Update No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (ASC 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement ("ASU 2018-15"). This guidance provides that implementation costs be evaluated for capitalization using the same criteria as that used for internal-use software development costs, with amortization expense being recorded in the same income statement expense line as the hosted service costs and over the expected term of the hosting arrangement. We are currently evaluating the impact of this guidance on our condensed consolidated financial statements and related disclosures. We do not expect the adoption of ASU 2018-15 to have a material impact on our consolidated financial statements. The standard is effective for public entities' interim and annual periods beginning after December 15, 2018. As we will cease to be an emerging growth company as of December 31, 2020, we expect to adopt the standard on December 31, 2020, presenting the initial application of ASC 350 beginning on January 1, 2020, in our annual financial statements included in our Form 10-K for year ended December 31, 2020.
Revenue recognition	Revenue recognition Revenue is recognized upon transfer of control of promised products or services to customers in an amount that reflects the consideration we expect to receive in exchange for those products or services. We enter into contracts that can include various combinations of products and services, each of which are distinct and accounted for as separate performance obligations. Revenue is recognized net of any taxes collected from customers, which are subsequently remitted to governmental authorities. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in Topic 606. Our contracts with customers often include promises to transfer multiple products and services to a customer. Determining whether products and services are considered distinct performance obligations that should be accounted for separately versus together may require significant judgment. For contracts with multiple performance obligations, we allocate the contract transaction price to each performance obligation using our estimate of the standalone selling price ("SSP") of each distinct good or service in the contract. Judgment is required to determine the SSP for each distinct performance obligation. We analyze separate sales of our products and services as a basis for estimating the SSP of our products and services. We then use that SSP as the basis for allocating the transaction price when our product and services are sold together in a contract with multiple performance obligations. In instances where SSP is not directly observable, such as when we do not sell the product or service separately, we determine the SSP using information that may include market conditions and other observable inputs. We typically have more than one SSP for individual products and services due to the stratification of those products and services by customers and circumstances. In these instances, we may use information, such geographic region and distribution channel, in determining the SSP. The transaction price in a contract is typically equal to the minimum commit price in the contract less any discounts provided. Because our typical contracts represent distinct services delivered over time with the same pattern of transfer to the customer, usage-based consideration primarily related to actual consumption over the minimum commit levels is allocated to the period to which it relates. The amount of consideration recognized for usage above the minimum commit price is limited to the amount we expect to be entitled to receive in exchange for providing services. We have elected to apply the practical expedient for estimating and disclosing the variable consideration when variable consideration is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct good or service that forms part of a single performance obligation from our remaining performance obligations under these contracts. Performance obligations represent stand-ready obligations that are satisfied over time as the customer simultaneously receives and consumes the benefits provided by us. These obligations can be content delivery, security, professional services, support, edge cloud platform services, and others. Accordingly, our revenue is recognized over time, consistent with the pattern of benefit provided to the customer over the term of the agreement. At times, customers may request changes that either amend, replace, or cancel existing contracts. Judgment is required to determine whether the specific facts and circumstances within the contracts should be accounted for as a separate contract or as a modification.
Fair value of financial instruments	Fair Value of Financial Instruments For certain of our financial instruments, including cash held in banks, accounts receivable, and accounts payable, the carrying amounts approximate fair value due to their short maturities, and are therefore excluded from the fair value tables below. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. There is a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1—Observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3—Unobservable inputs that are supported by little or no market activity, which require management judgment or estimation. We measure our cash equivalents, marketable securities, and restricted cash at fair value. We classify our cash equivalents, marketable securities and restricted cash within Level 1 or Level 2 because we value these investments using quoted market prices or alternative pricing sources and models utilizing market observable inputs. The fair value of our Level 1 financial assets is based on quoted market prices of the identical underlying security. The fair value of our Level 2 financial assets is based on inputs that are directly or indirectly observable in the market, including the readily available pricing sources for the identical underlying security that may not be actively traded.

Revenue (Tables)

Revenue (Tables)	9 Months Ended
	Sep. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue by Geographic Area	The following table presents our net revenue by geographic region: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) United States $ 49,140 $ 35,473 $ 136,194 $ 101,416 Asia Pacific 10,306 4,607 34,157 12,747 Europe 8,003 7,108 23,549 19,890 All other 3,189 2,609 14,325 7,473 Total revenue $ 70,638 $ 49,797 $ 208,225 $ 141,526
Revenue by Customer Type	The following table presents our net revenue for enterprise and non-enterprise customers: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) (in thousands) Enterprise customers $ 63,353 $ 42,765 $ 186,490 $ 121,230 Non-enterprise customers 7,285 7,032 21,735 20,296 Total revenue $ 70,638 $ 49,797 $ 208,225 $ 141,526
Contract Assets and Liabilities	The following table presents our contract assets and contract liabilities as of September 30, 2020 and as of December 31, 2019: As of September 30, 2020 As of December 31, 2019 (in thousands) Contract assets $ 403 $ 271 Contract liabilities $ 42 $ 317 The following table presents the revenue recognized during the three and nine months ended September 30, 2020 and 2019 from amounts included in the contract liability at the beginning of the period: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) Revenue recognized in the period from: Amounts included in contract liability at the beginning of the period $ 37 $ 518 $ 310 $ 1,517
Costs to Obtain Contracts	As of September 30, 2020 and December 31, 2019, our costs to obtain contracts were as follows: As of September 30, 2020 As of December 31, 2019 (in thousands) Deferred contract costs $ 11,693 $ 6,804

Investments and Fair Value Me_2

Investments and Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of Cash, Cash Equivalents, and Marketable Securities	Our total cash, cash equivalents and marketable securities consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Cash and cash equivalents: Cash $ 273,734 $ 11,623 Money market funds 36,234 2,020 Commercial paper — 2,499 Total cash and cash equivalents $ 309,968 $ 16,142 Marketable securities: Corporate notes and bonds $ 14,391 $ 17,470 Commercial paper 17,464 5,481 U.S. Treasury securities 60,447 78,160 Asset-backed securities — 13,856 Total marketable securities $ 92,302 $ 114,967
Schedule of Available-For-Sale Investments	The following table summarizes adjusted cost, gross unrealized gains and losses, and fair value related to available-for-sale securities classified as marketable securities on the accompanying Condensed Consolidated Balance Sheets as of September 30, 2020 and December 31, 2019: As of September 30, 2020 Amortized Gross Gross Fair (in thousands) Corporate notes and bonds $ 14,348 $ 43 $ — $ 14,391 Commercial paper 17,464 — — 17,464 U.S. Treasury securities 60,253 194 — 60,447 Total available-for-sale investments $ 92,065 $ 237 $ — $ 92,302 As of December 31, 2019 Amortized Gross Gross Fair (in thousands) Corporate notes and bonds $ 17,462 $ 9 $ (1) $ 17,470 Commercial paper 5,481 — — 5,481 U.S. Treasury securities 78,075 85 — 78,160 Asset-backed securities 13,852 4 — 13,856 Total available-for-sale investments $ 114,870 $ 98 $ (1) $ 114,967
Financial Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis	Financial assets and liabilities measured and recorded at fair value on a recurring basis consisted of the following types of instruments: As of September 30, 2020 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents: Money market funds $ 36,234 $ — $ — $ 36,234 Total cash equivalents 36,234 — — 36,234 Marketable securities: Corporate notes and bonds — 14,391 — 14,391 Commercial paper — 17,464 — 17,464 U.S. Treasury securities — 60,447 — 60,447 Asset-backed securities — — — — Total marketable securities — 92,302 — 92,302 Restricted cash: Money market funds 70,087 — — 70,087 Total restricted cash 70,087 — — 70,087 Total financial assets $ 106,321 $ 92,302 $ — $ 198,623 As of December 31, 2019 Level 1 Level 2 Level 3 Total (in thousands) Cash equivalents: Money market funds $ 2,020 $ — $ — $ 2,020 Commercial paper — 2,499 — 2,499 Total cash equivalents 2,020 2,499 — 4,519 Marketable securities: Corporate notes and bonds — 17,470 — 17,470 Commercial paper — 5,481 — 5,481 U.S. Treasury securities — 78,160 — 78,160 Asset-backed securities — 13,856 — 13,856 Total marketable securities — 114,967 — 114,967 Restricted cash: Money market funds 70,087 — — 70,087 Total restricted cash 70,087 — — 70,087 Total financial assets $ 72,107 $ 117,466 $ — $ 189,573

Balance Sheet Information (Tabl

Balance Sheet Information (Tables)	9 Months Ended
	Sep. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Computer and networking equipment $ 121,096 $ 89,830 Leasehold improvements 3,319 3,285 Furniture and fixtures 684 681 Office equipment 662 579 Internal-use software 19,221 13,901 Property and equipment, gross $ 144,982 $ 108,276 Accumulated depreciation and amortization (61,484) (48,239) Property and equipment, net $ 83,498 $ 60,037
Schedule of Accrued Expenses	Accrued expenses consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Accrued compensation and related benefits $ 21,362 $ 8,734 Sales and use tax payable 5,324 3,938 Accrued acquisition-related costs 4,436 — Accrued colocation and bandwidth costs 3,886 3,237 Other accrued liabilities 3,551 3,969 Total accrued expenses $ 38,559 $ 19,878
Schedule of Other Current Liabilities	Other current liabilities consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Liability for early-exercised stock options $ 257 $ 467 Deferred revenue 42 317 Accrued computer and networking equipment 8,977 7,060 Other current liabilities 279 325 Total other current liabilities $ 9,555 $ 8,169
Schedule of Other Long-Term Liabilities	Other long-term liabilities consisted of the following: As of September 30, As of December 31, 2020 2019 (in thousands) Deferred rent $ 3,731 $ 634 Other long-term liabilities 213 404 Total other long-term liabilities $ 3,944 $ 1,038

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the Carrying Amount of Goodwill	The changes in the carrying amount of goodwill for the nine months ended September 30, 2020 are as follows: Nine months ended (in thousands) Balance as of December 31, 2019 $ 372 Foreign currency translation (10) Balance as of September 30, 2020 $ 362
Schedule of Intangible Assets	As of September 30, 2020 and December 31, 2019, our intangible assets consisted of the following: As of September 30, 2020 As of December 31, 2019 Gross carrying value Accumulated amortization Net carrying value Gross carrying value Accumulated amortization Net carrying value (in thousands) Intangible assets: In-process research and development ("IPR&D") $ 368 $ — $ 368 $ — $ — $ — Internet protocol addresses 2,891 (506) 2,385 1,448 (362) 1,086 Domain name 39 — 39 39 — 39 Total intangible assets $ 3,298 $ (506) $ 2,792 $ 1,487 $ (362) $ 1,125
Expected Amortization Expense of Intangible Assets	The annual expected amortization expense of intangible assets subject to amortization as of September 30, 2020 is as follows: As of September 30, 2020 (in thousands) Remainder of 2020 $ 72 2021 298 2022 302 2023 302 2024 292 Thereafter 1,158 Total $ 2,424

Debt Instruments (Tables)

Debt Instruments (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Capital Lease Agreements	The following table reflects the Capital Lease agreements under our single master Capital Lease agreement entered into in June 2017: Date of Signed Agreement Date of Commencement, per Signed Agreement Amount of Network Equipment (in millions) Annual Interest Rate Term of Agreement (in years) June 2017 June 2017 $ 5.0 5.24 % 4.0 March 2018 March 2018 $ 0.5 5.38 % 4.0 February 2019 February 2019 $ 2.9 5.38 % 3.0 March 2019 March 2019 $ 1.3 5.38 % 3.0 August 2019 August 2019 $ 1.3 6.33 % 3.0 November 2019 November 2019 $ 2.2 5.69 % 3.0 December 2019 December 2019 $ 1.0 5.42 % 3.0 January 2020 February 2020 $ 1.0 5.42 % 3.0 March 2020 April 2020 $ 2.3 5.42 % 3.0 June 2020 July 2020 $ 3.6 4.95 % 3.0 September 2020 October 2020 $ 1.3 4.95 % 3.0 September 2020 October 2020 $ 2.2 4.95 % 3.0
Carrying Values of Debt Agreements	The following table reflects the carrying values of the debt and capital lease agreements as of September 30, 2020 and December 31, 2019: As of September 30, As of December 31, 2020 2019 (in thousands) Liability component: Principal amount—Cash Collateralized Revolving Credit Agreement $ 20,300 $ 20,300 Less: unamortized debt issuance costs (161) (219) Less: current portion of long-term debt — — Long-term debt, less current portion—Cash Collateralized Revolving Credit Agreement $ 20,139 $ 20,081 Principal amount—Capital Lease Agreement 11,928 9,549 Less: current portion of long-term debt (6,060) (4,472) Long-term debt, less current portion—Capital Lease Agreement $ 5,868 $ 5,077 Total long-term debt, less current portion $ 26,007 $ 25,158
Schedule of Contractual Future Repayments	Contractual future repayments for our debt and capital lease obligations as of September 30, 2020 are as follows: Principal Interest Total (in thousands) Remainder of 2020 $ 1,872 $ 926 $ 2,798 2021 6,921 1,350 8,271 2022 25,150 982 26,132 2023 1,795 30 1,825 2024 — — — Thereafter — — — Total $ 35,738 $ 3,288 $ 39,026

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Purchase Commitments	Our minimum future commitments related to cost of revenue related agreements as of September 30, 2020 were as follows: Cost of Revenue Commitments (in thousands) Remainder of 2020 $ 12,388 2021 35,411 2022 10,548 2023 3,141 2024 523 Thereafter 816 Total $ 62,827

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Schedule of Stock Option Activity	The following table summarizes stock option activity during the nine months ended September 30, 2020: Shares Weighted- Weighted- Aggregate (in thousands) (in years) (in thousands) Outstanding at December 31, 2019 11,269 $ 4.68 7.3 $ 173,471 Granted — — Exercised (3,803) 3.36 Cancelled/forfeited (176) 8.80 Outstanding at September 30, 2020 7,290 $ 5.28 6.8 $ 644,502 Vested and exercisable at September 30, 2020 4,296 $ 3.41 5.9 $ 387,817
Employee Stock Purchase Plan, Valuation Assumptions	We estimated the fair value of stock option awards using the Black-Scholes option pricing model with the following weighted-average assumptions: Nine months ended September 30, 2020 2019 Fair value of common stock N/A $12.38 Expected term (in years) N/A 6.48 Risk-free interest rate N/A 2.30% Expected volatility N/A 40.0% Dividend yield N/A —% We estimated the fair value of shares granted under the ESPP on the first date of the offering period using the Black-Scholes option pricing model with the following assumptions: Nine months ended September 30, 2020 2019 Fair value of common stock $14.09 $6.92 Expected term (in years) 0.5 0.5 Risk-free interest rate 0.85% 2.35% Expected volatility 52.0% 36.4% Dividend yield —% —%
Schedule of Unvested Exercised Options	The activity of non-vested shares as a result of early exercise of options granted to employees and non-employees, is as follows: Nine months ended September 30, 2020 (in thousands) Beginning balance as of December 31, 2019 200 Early exercise of options — Vested (94) Repurchased Ending balance as of September 30, 2020 106
Schedule of Restricted Stock Units	The following table summarizes RSU activity during the nine months ended September 30, 2020: Shares Weighted-Average (in thousands) RSUs outstanding as of December 31, 2019 1,641 $ 20.07 Granted 3,726 24.62 Vested (905) 21.52 Cancelled/forfeited (108) 21.53 RSUs outstanding as of September 30, 2020 4,354 $ 23.67
Schedule of Stock-Based Compensation Expense	The following table summarizes the components of total stock-based compensation expense included in the accompanying Condensed Consolidated Statements of Operations: Three months ended September 30, Nine months ended September 30, 2020 2019 2020 2019 (in thousands) Stock-based compensation expense by caption: Cost of revenue $ 929 $ 438 $ 2,634 $ 875 Research and development 4,371 968 10,095 2,114 Sales and marketing 3,194 929 11,753 1,894 General and administrative 3,648 1,505 10,270 2,667 Total $ 12,142 $ 3,840 $ 34,752 $ 7,550

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The shares issued in the IPO, the shares issued pursuant to the exercise by the underwriters of an option to purchase additional shares, and the shares of Class A and Class B common stock issued upon conversion of the outstanding shares of convertible preferred stock in the IPO are included in the table below, weighted for the period outstanding: Three months ended September 30, 2020 2019 Class A (1) Class B (2) Class A (1) Class B (2) (in thousands, except per share amounts) Net loss attributable to common stockholders $ (20,763) $ (3,015) (1,703) $ (10,460) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 92,510 13,432 13,054 80,186 Net loss per share attributable to common stockholders, basic and diluted $ (0.22) $ (0.22) $ (0.13) $ (0.13) Nine months ended September 30, 2020 2019 Class A (1) Class B (2) Class A (1) Class B (2) (in thousands, except per share amounts) Net loss attributable to common stockholders $ (39,670) $ (10,558) $ (4,116) $ (33,361) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 79,307 21,106 6,555 53,124 Net loss per share attributable to common stockholders, basic and diluted $ (0.50) $ (0.50) $ (0.63) $ (0.63) __________ (1) Class A common stock includes the issuance of 12.9 million shares of Class A common stock issued by us in connection with our IPO and shares issued upon the exercise of options and vesting of RSUs subsequent to our IPO. It also includes the shares issued in connection with our follow-on offering on May 26, 2020.
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive are as follows: Number of Shares As of September 30, 2020 2019 (in thousands) Stock options 7,290 12,459 RSUs 4,354 864 Early exercised stock options 106 240 Common stock warrants — 183 Shares issuable pursuant to the ESPP 90 230 PSUs 88 — Total 11,928 13,976

Information About Revenue and_2

Information About Revenue and Geographic Areas (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Schedule of Long-Lived Assets by Geographic Region	The following table presents long-lived assets by geographic region: As of September 30, As of December 31, 2020 2019 (in thousands) United States $ 54,734 $ 40,747 All other countries 28,764 19,290 Total long-lived assets $ 83,498 $ 60,037

Nature of Business (Details)

Nature of Business (Details) $ / shares in Units, $ in Thousands	May 26, 2020USD ($)$ / sharesshares	May 21, 2019USD ($)$ / sharesshares	May 03, 2019	Sep. 30, 2020locationmarketshares	Sep. 30, 2019shares	Sep. 30, 2020USD ($)locationmarketshares	Sep. 30, 2019USD ($)shares	Dec. 31, 2019shares	May 20, 2019series_of_stock$ / shares
Class of Stock [Line Items]
Points of presence | location				72		72
Number of operating markets | market				55		55
Common stock, stock split ratio			0.5
Proceeds from initial public offering, net of underwriting discounts | $						$ 0	$ 192,510
Number of convertible preferred stock series | series_of_stock									7
Preferred series par value (in dollars per share) | $ / shares									$ 0.00002
Convertible preferred stock shares issued (in shares)				0		0		0
Convertible preferred stock shares outstanding (in shares)				0		0		0
Proceeds from follow-on public offering, net of underwriting fees | $						$ 274,896	$ 0
Common Class A
Class of Stock [Line Items]
Shares issued (in shares)	6,900,000
Common stock price per share (in dollars per share) | $ / shares	$ 41.50
Proceeds from follow-on public offering, net of underwriting fees | $	$ 274,900
Common Class B
Class of Stock [Line Items]
Number of shares converted (in shares)	53,600,000			0	51,722	144,635,000	224,102
Convertible securities, conversion ratio		1
IPO | Common Class A
Class of Stock [Line Items]
Shares issued (in shares)		12,937,500
Common stock price per share (in dollars per share) | $ / shares		$ 16
Proceeds from initial public offering, net of underwriting discounts | $		$ 192,500
Over-Allotment Option | Common Class A
Class of Stock [Line Items]
Shares issued (in shares)	900,000	1,687,500
Proceeds from initial public offering, net of underwriting discounts | $		$ 25,100
Common Stock | Common Class A
Class of Stock [Line Items]
Shares issued (in shares)						6,900,000	12,937,500
Number of shares converted (in shares)				3,371,024		22,727,685
Common Stock | Common Class B
Class of Stock [Line Items]
Number of shares converted (in shares)		53,630,213		(3,371,024)		22,727,685	53,630,213

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	9 Months Ended
	Sep. 30, 2020
Revenue | Major Customer | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%

Revenue - Narrative (Details)

Revenue - Narrative (Details)	9 Months Ended
	Sep. 30, 2020USD ($)
Concentration Risk [Line Items]
Enterprise customer threshold	$ 100,000
Revenue, performance obligation, description of payment terms	Payment terms on invoiced amounts are typically 15 to 45 days.
Geographic Concentration Risk | Revenue | Singapore
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%

Revenue - Revenue by Geographic

Revenue - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 70,638	$ 49,797	$ 208,225	$ 141,526
United States
Disaggregation of Revenue [Line Items]
Revenue	49,140	35,473	136,194	101,416
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenue	10,306	4,607	34,157	12,747
Europe
Disaggregation of Revenue [Line Items]
Revenue	8,003	7,108	23,549	19,890
All other
Disaggregation of Revenue [Line Items]
Revenue	$ 3,189	$ 2,609	$ 14,325	$ 7,473

Revenue - Revenue by Customer T

Revenue - Revenue by Customer Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 70,638	$ 49,797	$ 208,225	$ 141,526
Enterprise customers
Disaggregation of Revenue [Line Items]
Revenue	63,353	42,765	186,490	121,230
Non-enterprise customers
Disaggregation of Revenue [Line Items]
Revenue	$ 7,285	$ 7,032	$ 21,735	$ 20,296

Revenue - Contract Assets and L

Revenue - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Contract assets	$ 403		$ 403		$ 271
Contract liabilities	42		42		$ 317
Revenue recognized in the period from:
Amounts included in contract liability at the beginning of the period	$ 37	$ 518	$ 310	$ 1,517

Revenue - Remaining Performance

Revenue - Remaining Performance Obligation (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue performance obligation	$ 100	$ 70.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation, percentage	80.00%
Remaining performance obligation, timing of satisfaction	12 months

Revenue - Costs to Obtain Contr

Revenue - Costs to Obtain Contracts (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Capitalized contract costs, amortization period	5 years		5 years
Deferred contract costs	$ 11,693		$ 11,693		$ 6,804
Amortization of deferred contract costs	$ 900	$ 600	$ 2,375	$ 1,690

Investments and Fair Value Me_3

Investments and Fair Value Measurements - Cash, Cash Equivalent and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	$ 309,968	$ 16,142	$ 54,706
Marketable securities	92,302	114,967
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Marketable securities	14,391	17,470
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Marketable securities	17,464	5,481
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Marketable securities	60,447	78,160
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Marketable securities	0	13,856
Cash
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	273,734	11,623
Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	36,234	2,020
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents	$ 0	$ 2,499

Investments and Fair Value Me_4

Investments and Fair Value Measurements - Available-For-Sale Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 92,065	$ 114,870
Gross Unrealized Gain	237	98
Gross Unrealized Loss	0	(1)
Fair Value	92,302	114,967
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	14,348	17,462
Gross Unrealized Gain	43	9
Gross Unrealized Loss	0	(1)
Fair Value	14,391	17,470
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	17,464	5,481
Gross Unrealized Gain	0	0
Gross Unrealized Loss	0	0
Fair Value	17,464	5,481
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	60,253	78,075
Gross Unrealized Gain	194	85
Gross Unrealized Loss	0	0
Fair Value	$ 60,447	78,160
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		13,852
Gross Unrealized Gain		4
Gross Unrealized Loss		0
Fair Value		$ 13,856

Investments and Fair Value Me_5

Investments and Fair Value Measurements - Narrative (Details) - security	Sep. 30, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Securities in a continuous loss position (in securities)	0	0

Investments and Fair Value Me_6

Investments and Fair Value Measurements - Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 36,234	$ 4,519
Marketable securities	92,302	114,967
Total restricted cash	70,087	70,087	$ 87
Total financial assets	198,623	189,573
Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	14,391	17,470
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	17,464	5,481
U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	60,447	78,160
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	13,856
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	36,234	2,020
Total restricted cash	70,087	70,087
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		2,499
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	36,234	2,020
Marketable securities	0	0
Total restricted cash	70,087	70,087
Total financial assets	106,321	72,107
Level 1 | Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 1 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 1 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	36,234	2,020
Total restricted cash	70,087	70,087
Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	2,499
Marketable securities	92,302	114,967
Total restricted cash	0	0
Total financial assets	92,302	117,466
Level 2 | Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	14,391	17,470
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	17,464	5,481
Level 2 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	60,447	78,160
Level 2 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	13,856
Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total restricted cash	0	0
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		2,499
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Marketable securities	0	0
Total restricted cash	0	0
Total financial assets	0	0
Level 3 | Corporate notes and bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 3 | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 3 | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Total restricted cash	$ 0	0
Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		$ 0

Balance Sheet Information - Pro

Balance Sheet Information - Property and equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 144,982	$ 108,276
Accumulated depreciation and amortization	(61,484)	(48,239)
Property and equipment, net	83,498	60,037
Computer and networking equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	121,096	89,830
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,319	3,285
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	684	681
Office equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	662	579
Internal-use software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	19,221	13,901
Property and equipment, net	$ 12,100	$ 8,500

Balance Sheet Information - Nar

Balance Sheet Information - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Depreciation and amortization	$ 4,900,000	$ 4,000,000	$ 14,300,000	$ 11,600,000
Gain on disposal of property and equipment			133,000	(43,000)
Property and equipment, net	83,498,000		83,498,000		$ 60,037,000
Internal-use software
Property, Plant and Equipment [Line Items]
Depreciation and amortization	500,000	500,000	1,700,000	1,600,000
Property and equipment, net	12,100,000		12,100,000		$ 8,500,000
Computer and networking equipment
Property, Plant and Equipment [Line Items]
Gain on disposal of property and equipment	$ 100,000	$ 0	$ 100,000	$ 0

Balance Sheet Information - Acc

Balance Sheet Information - Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Accrued compensation and related benefits	$ 21,362	$ 8,734
Sales and use tax payable	5,324	3,938
Accrued acquisition-related costs	4,436	0
Accrued colocation and bandwidth costs	3,886	3,237
Other accrued liabilities	3,551	3,969
Total accrued expenses	$ 38,559	$ 19,878

Balance Sheet Information - Oth

Balance Sheet Information - Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Liability for early-exercised stock options	$ 257	$ 467
Deferred revenue	42	317
Accrued computer and networking equipment	8,977	7,060
Other current liabilities	279	325
Total other current liabilities	$ 9,555	$ 8,169

Balance Sheet Information - O_2

Balance Sheet Information - Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Deferred rent	$ 3,731	$ 634
Other long-term liabilities	213	404
Total other long-term liabilities	$ 3,944	$ 1,038

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 372
Foreign currency translation	(10)
Goodwill, ending balance	$ 362

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, accumulated amortization	$ (506)	$ (362)
Finite-lived intangible assets, net carrying value	2,424
Intangible assets, gross carrying value	3,298	1,487
Intangible assets, net carrying value	2,792	1,125
In-process research and development ("IPR&D")
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	368	0
Internet protocol addresses
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	2,891	1,448
Finite-lived intangible assets, accumulated amortization	(506)	(362)
Finite-lived intangible assets, net carrying value	2,385	1,086
Domain name
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 39	$ 39

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Finite-Lived Intangible Assets [Line Items]
Purchases of intangible assets			$ 1,811,000	$ 636,000
Amortization of intangible assets	$ 100,000	$ 100,000	100,000	100,000
In-process research and development ("IPR&D")
Finite-Lived Intangible Assets [Line Items]
Purchases of intangible assets			400,000
Internet Protocol Addresses and Domain Names
Finite-Lived Intangible Assets [Line Items]
Purchases of intangible assets	$ 0		$ 1,400,000
Internet protocol addresses
Finite-Lived Intangible Assets [Line Items]
Purchases of intangible assets		600,000		600,000
Domain name
Finite-Lived Intangible Assets [Line Items]
Purchases of intangible assets		$ 100,000		$ 100,000

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Expected Amortization of Intangible Assets (Details) $ in Thousands	Sep. 30, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Remainder of 2020	$ 72
2021	298
2022	302
2023	302
2024	292
Thereafter	1,158
Finite-lived intangible assets, net carrying value	$ 2,424

Debt Instruments - Capital Leas

Debt Instruments - Capital Lease Agreement (Details) - USD ($)	1 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Dec. 31, 2019	Nov. 30, 2019	Aug. 31, 2019	Mar. 31, 2019	Feb. 28, 2019	Mar. 31, 2018	Jun. 30, 2017
Debt Instrument [Line Items]
Capital lease obligations	$ 11,928,000				$ 9,549,000
Network equipment | Capital Lease Obligations
Debt Instrument [Line Items]
Capital lease, face amount		$ 3,600,000	$ 2,300,000	$ 1,000,000	$ 1,000,000	$ 2,200,000	$ 1,300,000	$ 1,300,000	$ 2,900,000	$ 500,000	$ 5,000,000
Interest rate, stated percentage		4.95%	5.42%	5.42%	5.42%	5.69%	6.33%	5.38%	5.38%	5.38%	5.24%
Capital lease term		3 years	3 years	3 years	3 years	3 years	3 years	3 years	3 years	4 years	4 years
Network equipment | Capital Lease Obligations | Capital Lease September 2020, 1
Debt Instrument [Line Items]
Capital lease, face amount	$ 1,300,000
Interest rate, stated percentage	4.95%
Capital lease term	3 years
Network equipment | Capital Lease Obligations | Capital Lease September 2020, 2
Debt Instrument [Line Items]
Capital lease, face amount	$ 2,200,000
Interest rate, stated percentage	4.95%
Capital lease term	3 years

Debt Instruments - Cash Collate

Debt Instruments - Cash Collateralized Revolving Credit Facility (Details) - USD ($)	9 Months Ended
	Sep. 30, 2020	Nov. 04, 2020	Dec. 31, 2019	Nov. 30, 2019
Debt Instrument [Line Items]
Amount of debt outstanding	$ 20,300,000		$ 20,300,000
Subsequent Event
Debt Instrument [Line Items]
Amount of debt outstanding		$ 20,300,000
Cash collateral for line of credit		$ 70,100,000
Line of Credit | Second Lien Credit Facility
Debt Instrument [Line Items]
Debt facility, maximum borrowing amount				$ 70,000,000
Effective interest rate	3.46%
Line of credit, unused capacity, commitment fee percentage	0.20%
Line of Credit | Second Lien Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%

Debt Instruments - Carrying Val

Debt Instruments - Carrying Values of Debt Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Principal amount—Cash Collateralized Revolving Credit Agreement	$ 20,300	$ 20,300
Less: unamortized debt issuance costs	(161)	(219)
Less: current portion of long-term debt	0	0
Long-term debt, less current portion—Cash Collateralized Revolving Credit Agreement	20,139	20,081
Principal amount—Capital Lease Agreement	11,928	9,549
Less: current portion of long-term debt	(6,060)	(4,472)
Long-term debt, less current portion—Capital Lease Agreement	5,868	5,077
Total long-term debt, less current portion	$ 26,007	$ 25,158

Debt Instruments - Maturities S

Debt Instruments - Maturities Schedule (Details) $ in Thousands	Sep. 30, 2020USD ($)
Principal
Principal - Remainder of 2020	$ 1,872
Principal - 2021	6,921
Principal - 2022	25,150
Principal - 2023	1,795
Principal - 2024	0
Principal - thereafter	0
Principal - Total	35,738
Interest
Interest - Remainder of 2020	926
Interest - 2021	1,350
Interest - 2022	982
Interest - 2023	30
Interest - 2024	0
Interest - thereafter	0
Interest - Total	3,288
Total
Total - Remainder of 2020	2,798
Total - 2021	8,271
Total - 2022	26,132
Total - 2023	1,825
Total - 2024	0
Total - thereafter	0
Total	$ 39,026

Debt Instruments - Narrative (D

Debt Instruments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Debt Disclosure [Abstract]
Interest expense	$ 0.4	$ 0.6	$ 1.1	$ 4.8

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 27, 2020numberOfLawsuits
Commitments and Contingencies Disclosure [Abstract]
Rent expense | $	$ 2	$ 1.8	$ 6.3	$ 4.9
Sublease income | $	$ 0.3	$ 0.3	$ 0.9	$ 0.9
Number of lawsuits consolidated | numberOfLawsuits					2
Number of lawsuits | numberOfLawsuits					1

Commitments and Contingencies_2

Commitments and Contingencies - Purchase Commitments (Details) $ in Thousands	Sep. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2020	$ 12,388
2021	35,411
2022	10,548
2023	3,141
2024	523
Thereafter	816
Total	$ 62,827

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock (Details)	Sep. 30, 2020voteshares	Dec. 31, 2019shares	May 31, 2019vote$ / sharesshares
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)			10,000,000
Preferred stock, par value (in USD per share) | $ / shares			$ 0.00002
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common Class A
Class of Stock [Line Items]
Common stock, shares authorized (in shares)			1,000,000,000
Common stock, par value (in USD per share) | $ / shares			$ 0.00002
Common stock, voting rights (votes per share) | vote	1		1
Common stock, shares issued (in shares)	95,500,000	61,000,000
Common stock, shares outstanding (in shares)	95,500,000	61,000,000
Common Class B
Class of Stock [Line Items]
Common stock, shares authorized (in shares)			94,100,000
Common stock, voting rights (votes per share) | vote	10		10
Common stock, shares issued (in shares)	11,400,000	33,900,000
Common stock, shares outstanding (in shares)	11,400,000	33,900,000

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plans (Details) - USD ($)	1 Months Ended
	May 31, 2019	Sep. 30, 2020	Dec. 31, 2019
Shares issuable pursuant to the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum deduction of eligible compensation, percent	15.00%
Maximum purchase value during offering period, per employee	$ 25,000
Common Class B | 2011 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares reserved for future issuance (in shares)		23,600,000	23,600,000
Common stock, shares available for future issuance (in shares)		0	0
Common Class A | Shares issuable pursuant to the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares reserved for future issuance (in shares)		3,500,000	2,500,000
Common stock, shares available for future issuance (in shares)		2,900,000	2,200,000
Common Class A | 2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares reserved for future issuance (in shares)		19,200,000	14,400,000
Common stock, shares available for future issuance (in shares)		13,400,000	12,400,000

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pre-tax intrinsic value	$ 157.9	$ 12.7
Vesting of early exercised stock options	$ 6.5	$ 4.4
Weighted-average grant date fair value (in USD per share)	$ 6.05
2011 Equity Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	10 years
Award vesting period	4 years
2011 Equity Incentive Plan | Stock options | First Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	25.00%
2011 Equity Incentive Plan | Stock options | Remaining Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	36 months
2019 Equity Incentive Plan | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period	10 years
Award vesting period	4 years
2019 Equity Incentive Plan | Stock options | First Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	25.00%
2019 Equity Incentive Plan | Stock options | Remaining Period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	36 months

Stockholders' Equity - Stock _2

Stockholders' Equity - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2020	Dec. 31, 2019
Shares
Options outstanding, beginning balance (in shares)	11,269
Granted (in shares)	0
Exercised (in shares)	(3,803)
Cancelled/forfeited (in shares)	(176)
Options outstanding, ending balance (in shares)	7,290	11,269
Options vested and exercisable (in shares)			4,296
Stock Options Weighted Average Exercise Price
Options outstanding, weighted average exercise price, beginning of period (in USD per share)	$ 5.28	$ 4.68	$ 5.28	$ 4.68
Granted, weighted average exercise price (in USD per share)	0
Exercised, weighted average exercise price (in USD per share)	3.36
Cancelled/forfeited, weighted average exercise price (in USD per share)	8.80
Options outstanding, weighted average exercise price, end of period (in USD per share)	$ 5.28	$ 4.68
Vested and exercisable, weighted-average exercise price (in USD per share)			$ 3.41
Stock Option Activity, Additional Disclosures
Weighted-average remaining contractual period	6 years 9 months 18 days	7 years 3 months 18 days
Aggregate intrinsic value			$ 644,502	$ 173,471
Vested and exercisable, weighted average contractual term	5 years 10 months 24 days
Vested and exercisable, aggregate intrinsic value			$ 387,817

Stockholders' Equity - Employee

Stockholders' Equity - Employee Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 12,142	$ 3,840	$ 34,752	$ 7,550
Unrecognized stock-based compensation cost	12,400		12,400
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of common stock (in dollars per share)		$ 12.38		$ 12.38
Expected term (in years)				6 years 5 months 23 days
Risk-free interest rate				2.30%
Expected volatility				40.00%
Dividend yield				0.00%
Stock-based compensation expense	$ 1,800	$ 2,100	$ 5,700	$ 5,400
Weighted-average period of recognition			2 years 1 month 17 days

Stockholders' Equity - Early Ex

Stockholders' Equity - Early Exercise of Stock Options (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested shares (in shares)	199,895	105,847	199,895
Shares
Beginning balance (in shares)	199,895
Ending balance (in shares)	105,847
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested shares (in shares)	106,000	106,000	200,000
Other long-term liabilities		$ 0.5	$ 0.9
Shares
Beginning balance (in shares)	200,000
Early exercise of options (in shares)	0
Vested (in shares)	(94,000)
Repurchased (in shares)
Ending balance (in shares)	106,000

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Units (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Weighted-Average  Grant Date Fair Value Per Share
Stock-based compensation expense	$ 12,142	$ 3,840	$ 34,752	$ 7,550
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			4 years
Award vesting percentage			25.00%
Offering period duration			36 months
Shares
Beginning balance (in shares)			1,641
Granted (in shares)			3,726
Vested (in shares)			(905)
Cancelled/forfeited (in shares)			(108)
Ending balance (in shares)	4,354		4,354
Weighted-Average  Grant Date Fair Value Per Share
Beginning balance (in USD per share)			$ 20.07
Granted (in USD per share)			24.62
Vested (in USD per share)			21.52
Forfeited (in USD per share)			21.53
Ending balance (in USD per share)	$ 23.67		$ 23.67
Stock-based compensation expense	$ 10,600	$ 700	$ 28,000	$ 700
Expense related to modification	4,800		4,800
Modification expense, incremental fair value	100		100
Unrecognized stock-based compensation cost	$ 92,400		$ 92,400
Weighted-average period of recognition			3 years 4 months 2 days

Stockholders' Equity - Performa

Stockholders' Equity - Performance-Based Stock Units (Details) - PSUs	1 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2020shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)		87,918
Shares issued for each PSU, ratio		1
Award vesting percentage	25.00%
Performance Target One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance percentage	90.00%
Award vesting percentage	50.00%
Performance Target Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance percentage	100.00%
Award vesting percentage	100.00%
Performance Target Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance percentage	110.00%
Award vesting percentage	200.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target performance percentage	200.00%

Stockholders' Equity - ESPP (De

Stockholders' Equity - ESPP (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contributions withheld for taxes	$ 2,000	$ 2,300	$ 6,100	$ 3,100
Stock-based compensation expense	$ 12,142	$ 3,840	$ 34,752	$ 7,550
Common Class A | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased under ESPP (in shares)			226,288
Shares issuable pursuant to the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum employee contribution as a percentage of salary			15.00%
Offering period duration			6 months
Purchase price of common stock, percent			85.00%
Fair value of common stock (in dollars per share)	$ 14.09	$ 6.92	$ 14.09	$ 6.92
Expected term (in years)			6 months	6 months
Risk-free interest rate			0.85%	2.35%
Expected volatility			52.00%	36.40%
Dividend yield			0.00%	0.00%
Stock-based compensation expense	$ 400	$ 1,100	$ 2,300	$ 1,500
Shares issued under ESPP (in shares)		0	0	0

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 12,142,000	$ 3,840,000	$ 34,752,000	$ 7,550,000
Stock-based compensation capitalized to internal-use software	600,000	0	1,238,000	0
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	929,000	438,000	2,634,000	875,000
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	4,371,000	968,000	10,095,000	2,114,000
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3,194,000	929,000	11,753,000	1,894,000
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,648,000	$ 1,505,000	$ 10,270,000	$ 2,667,000

Stockholders' Equity - Common_2

Stockholders' Equity - Common Stock Warrant Liabilities (Details) - shares	May 26, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Common Class B
Class of Stock [Line Items]
Conversion of stock (in shares)	53,600,000	0	51,722	144,635,000	224,102

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Narrative (Details)	Sep. 30, 2020vote	May 31, 2019vote
Common Class A
Class of Stock [Line Items]
Common stock, voting rights (votes per share)	1	1
Common Class B
Class of Stock [Line Items]
Common stock, voting rights (votes per share)	10	10
Common Class B | Conversion Of Class B Common Stock To Class A Common Stock
Class of Stock [Line Items]
Common stock, conversion ratio	1

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Computation of EPS (Details) - USD ($) $ / shares in Units, $ in Thousands	May 26, 2020	May 21, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Class of Stock [Line Items]
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)			105,942,000	93,240,000	100,413,000	59,679,000
Net loss per share attributable to common shareholders, basic and diluted (in USD per share)			$ (0.22)	$ (0.13)	$ (0.50)	$ (0.63)
Common Class A
Class of Stock [Line Items]
Net loss attributable to common stockholders			$ (20,763)	$ (1,703)	$ (39,670)	$ (4,116)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)			92,510,000	13,054,000	79,307,000	6,555,000
Net loss per share attributable to common shareholders, basic and diluted (in USD per share)			$ (0.22)	$ (0.13)	$ (0.50)	$ (0.63)
Shares issued (in shares)	6,900,000
Common Class A | IPO
Class of Stock [Line Items]
Shares issued (in shares)		12,937,500
Common Class B
Class of Stock [Line Items]
Net loss attributable to common stockholders			$ (3,015)	$ (10,460)	$ (10,558)	$ (33,361)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)			13,432,000	80,186,000	21,106,000	53,124,000
Net loss per share attributable to common shareholders, basic and diluted (in USD per share)			$ (0.22)	$ (0.13)	$ (0.50)	$ (0.63)
Number of shares converted (in shares)	53,600,000		0	51,722	144,635,000	224,102

Net Loss Per Share Attributab_5

Net Loss Per Share Attributable to Common Stockholders - Antidilutive Securities (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	11,928	13,976
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	7,290	12,459
RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	4,354	864
Early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	106	240
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	183
Shares issuable pursuant to the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	90	230
PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	88	0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income taxes	$ 336	$ 46	$ 1,131	$ 183
Accrued payroll taxes, CARES Act	$ 2,700		$ 2,700

Information About Revenue and_3

Information About Revenue and Geographic Areas (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020USD ($)segment	Dec. 31, 2019USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment	1
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 83,498	$ 60,037
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	54,734	40,747
All other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total long-lived assets	$ 28,764	$ 19,290

Related Party Transactions (Det

Related Party Transactions (Details) - Related Party Promissory Note - Stockholder - USD ($)	1 Months Ended
	Jul. 31, 2016	Sep. 30, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Related party note receivable	$ 100,000
Number of shares converted (in shares)	53,125
Interest rate of promissory note	1.77%
Promissory note, amount outstanding		$ 0	$ 0

Subsequent Events - Merger with

Subsequent Events - Merger with Signal Sciences (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 01, 2020	May 31, 2019
Common Class A
Subsequent Event [Line Items]
Common stock, par value (in USD per share)		$ 0.00002
Subsequent Event | Common Class A
Subsequent Event [Line Items]
Common stock, par value (in USD per share)	$ 0.00002
Signal Sciences Corp. | Subsequent Event
Subsequent Event [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%
Aggregate consideration transferred	$ 775
Cash consideration transferred	$ 200
Shares issued in acquisition (in shares)	6,367,709
Signal Sciences Corp. | Subsequent Event | RSUs
Subsequent Event [Line Items]
Aggregate retention pool value	$ 50
Signal Sciences Corp. | Subsequent Event | Common Class A
Subsequent Event [Line Items]
Stock options assumed (in shares)	251,754