Twilio (TWLO) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Annual Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-37806
Entity Registrant Name	TWILIO INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-2574840
Entity Address, Address Line One	101 Spear Street
Entity Address, Address Line Two	First Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94105
City Area Code	415
Local Phone Number	390-2337
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	TWLO
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001447669
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Common Stock Class A
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		162,370,009
Common Stock Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		10,325,768

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 2,331,774	$ 933,885
Short-term marketable securities	3,375,284	2,105,906
Accounts receivable, net	257,854	251,167
Prepaid expenses and other current assets	129,063	81,377
Total current assets	6,093,975	3,372,335
Property and equipment, net	195,885	183,239
Operating right-of-use asset	241,328	258,610
Intangible assets, net	951,884	966,573
Goodwill	4,635,177	4,595,394
Other long-term assets	123,932	111,282
Total assets	12,242,181	9,487,433
Current liabilities:
Accounts payable	66,511	60,042
Accrued expenses and other current liabilities	293,658	252,895
Deferred revenue and customer deposits	93,516	87,031
Operating lease liability, current	46,239	48,338
Total current liabilities	499,924	448,306
Operating lease liability, noncurrent	214,456	229,905
Finance lease liability, noncurrent	19,933	17,856
Long-term debt	1,218,048	302,068
Other long-term liabilities	42,624	36,633
Total liabilities	1,994,985	1,034,768
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock	0	0
Class A and Class B common stock	171	164
Additional paid-in capital	11,618,698	9,613,246
Accumulated other comprehensive income	4,660	9,046
Accumulated deficit	(1,376,333)	(1,169,791)
Total stockholders’ equity	10,247,196	8,452,665
Total liabilities and stockholders’ equity	$ 12,242,181	$ 9,487,433

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Revenue	$ 589,988	$ 364,868
Cost of revenue	291,684	171,333
Gross profit	298,304	193,535
Operating expenses:
Research and development	174,800	114,339
Sales and marketing	210,590	116,722
General and administrative	110,253	55,170
Total operating expenses	495,643	286,231
Loss from operations	(197,339)	(92,696)
Other expenses, net	(8,313)	(1,118)
Loss before provision for income taxes	(205,652)	(93,814)
Provision for income taxes	(890)	(977)
Net loss attributable to common stockholders	$ (206,542)	$ (94,791)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.24)	$ (0.68)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.24)	$ (0.68)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	167,160,458	139,231,594
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	167,160,458	139,231,594

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (206,542)	$ (94,791)
Other comprehensive loss:
Unrealized loss on marketable securities	(4,176)	(9,375)
Foreign currency translation	(210)	0
Total other comprehensive loss	(4,386)	(9,375)
Comprehensive loss attributable to common stockholders	$ (210,928)	$ (104,166)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders Equity - USD ($) $ in Thousands	Total	RSAs	Follow-on Public Offering	Common StockCommon Stock Class A	Common StockCommon Stock Class AFollow-on Public Offering	Common StockCommon Stock Class B	Additional Paid-In Capital	Additional Paid-In CapitalFollow-on Public Offering	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance (in shares) at Dec. 31, 2019				126,882,172		11,530,627
Balance at Dec. 31, 2019	$ 4,279,411			$ 124		$ 14	$ 4,952,999		$ 5,086	$ (678,812)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(94,791)									(94,791)
Exercises of vested stock options (in shares)				243,029		426,001
Exercises of vested stock options	8,231			$ 0		$ 0	8,231
Vesting of restricted stock units (in shares)				849,763		23,107
Vesting of restricted stock units	1			$ 1		$ 0
Value of equity awards withheld for tax liability (in shares)				(8,726)		(4,692)
Value of equity awards withheld for tax liability	(1,674)						(1,674)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)				618,103		(618,103)
Conversion of shares of Class B common stock into shares of Class A common stock				$ 1		$ (1)
Donated common stock (in shares)				22,102
Donated common stock	2,701						2,701
Unrealized loss on marketable securities	(9,375)								(9,375)
Foreign currency translation	0
Stock-based compensation	72,021						72,021
Balance (in shares) at Mar. 31, 2020				128,606,443		11,356,940
Balance at Mar. 31, 2020	4,256,525			$ 126		$ 13	5,034,278		(4,289)	(773,603)
Balance (in shares) at Dec. 31, 2019				126,882,172		11,530,627
Balance at Dec. 31, 2019	4,279,411			$ 124		$ 14	4,952,999		5,086	(678,812)
Balance (in shares) at Dec. 31, 2020				153,496,222		10,551,302
Balance at Dec. 31, 2020	8,452,665			$ 151		$ 13	9,613,246		9,046	(1,169,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(206,542)									(206,542)
Exercises of vested stock options (in shares)				248,008		211,371
Exercises of vested stock options	11,564			$ 0		$ 0	11,564
Vesting of restricted stock units (in shares)				913,966		0
Vesting of restricted stock units	0			$ 1		$ 0	(1)
Value of equity awards withheld for tax liability (in shares)				(6,989)		0
Value of equity awards withheld for tax liability	(2,774)						(2,774)
Conversion of shares of Class B common stock into shares of Class A common stock (in shares)				419,371		(419,371)
Conversion of shares of Class B common stock into shares of Class A common stock	0			$ 0		$ 0
Equity component from partial settlement of 2023 convertible senior notes (in shares)				1,158,381
Equity component from partial settlement of 2023 convertible senior notes	80,049			$ 2			80,047
Donated common stock (in shares)				22,102
Donated common stock	9,405						9,405
Issuance of common stock in connection with a follow-on public offering, net of underwriter discounts and issuance costs (in shares)					4,312,500
Issuance of common stock in connection with a follow-on public offering, net of underwriter discounts			$ 1,766,400		$ 4			$ 1,766,396
Costs related to the follow-on public offering	(727)
Issuance of restricted stock awards (in shares)		24,697
Unrealized loss on marketable securities	(4,176)								(4,176)
Foreign currency translation	(210)								(210)
Stock-based compensation	141,542						141,542
Balance (in shares) at Mar. 31, 2021				160,588,258		10,343,302
Balance at Mar. 31, 2021	$ 10,247,196			$ 158		$ 13	$ 11,618,698		$ 4,660	$ (1,376,333)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (206,542)	$ (94,791)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	59,592	32,239
Non-cash reduction to the right-of-use asset	11,711	8,023
Net amortization of investment premium and discount	4,240	343
Amortization of debt discount and issuance costs	3,373	6,178
Stock-based compensation	137,155	69,025
Amortization of deferred commissions	5,630	1,981
Allowance for credit losses	1,985	4,170
Value of donated common stock	9,405	2,701
Loss on extinguishment of debt	7,602	0
Other adjustments	3,089	1,866
Changes in operating assets and liabilities:
Accounts receivable	5,565	(23,123)
Prepaid expenses and other current assets	(29,912)	(8,130)
Other long-term assets	(15,232)	(5,759)
Accounts payable	(10,275)	(20,803)
Accrued expenses and other current liabilities	28,307	44,840
Deferred revenue and customer deposits	3,435	589
Operating lease liabilities	(12,053)	(7,008)
Other long-term liabilities	(2,570)	3,194
Net cash provided by operating activities	4,505	15,535
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisitions, net of cash acquired and other related payments	(66,926)	(2,377)
Purchases of marketable securities and other investments	(1,640,499)	(228,025)
Proceeds from sales and maturities of marketable securities	356,824	316,992
Capitalized software development costs	(10,434)	(8,626)
Purchases of long-lived and intangible assets	(4,986)	(6,319)
Net cash (used in) provided by investing activities	(1,366,021)	71,645
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from a public equity offering	1,766,400	0
Payments of costs related to public offerings	(360)	0
Proceeds from issuance of senior notes	987,500	0
Payments of debt issuance costs	(130)	0
Principal payments on debt and finance leases	(2,751)	(1,954)
Proceeds from exercises of stock options and shares issued in ESPP	11,564	8,231
Value of equity awards withheld for tax liabilities	(2,774)	(1,674)
Net cash provided by financing activities	2,759,449	4,603
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(44)	0
NET INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	1,397,889	91,783
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—Beginning of period	933,885	253,735
CASH, CASH EQUIVALENTS AND RESTRICTED CASH —End of period	2,331,774	345,518
Supplemental Cash Flow Information [Abstract]
Cash paid for income taxes, net	1,252	257
Cash paid for interest	263	198
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property, equipment and intangible assets, accrued but not paid	3,494	5,510
Purchases of property and equipment through finance leases	5,266	0
Value of common stock issued to settle convertible senior notes	422,716	0
Stock-based compensation capitalized in software development costs	4,650	3,418
Costs related to public debt and equity offerings, accrued but not paid	2,681	0
Costs related to proposed investment in Syniverse, accrued but not paid	$ 3,262	$ 0

Organization and Description of

Organization and Description of Business	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Twilio Inc. (the “Company”) was incorporated in the state of Delaware on March 13, 2008. The Company is the leading cloud communications platform and enables developers to build, scale and operate real-time customer engagement within their software applications via simple-to-use Application Programming Interfaces (“API”). The power, flexibility, and reliability offered by the Company’s software building blocks empower entities of virtually every shape and size to build world-class engagement into their customer experience. The Company’s headquarters are located in San Francisco, California, and the Company has subsidiaries in Australia, Bermuda, Brazil, Canada, Colombia, Czech Republic, Estonia, France, Germany, Hong Kong, India, Ireland, Japan, Mexico, the Netherlands, Serbia, Singapore, Spain, Sweden, the United Kingdom and the United States.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies (a) Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company's Annual Report on Form 10-K filed with the SEC on February 26, 2021 (“Annual Report”). The condensed consolidated balance sheet as of December 31, 2020, included herein, was derived from the audited financial statements as of that date, but may not include all disclosures including certain notes required by U.S. GAAP on an annual reporting basis. In the opinion of management, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss, stockholders' equity and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year 2021 or any future period. (b) Principles of Consolidation The condensed consolidated financial statements include the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated. (c) Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates are used for, but not limited to, revenue allowances and sales credit reserves; recoverability of long-lived and intangible assets; capitalization and useful life of the Company’s capitalized internal-use software development costs; fair value of acquired intangible assets and goodwill; accruals and contingencies. Estimates are based on historical experience and on various assumptions that the Company believes are reasonable under current circumstances. However, future events are subject to change and best estimates and judgments may require further adjustments, therefore, actual results could differ materially from those estimates. Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation. (d) Concentration of Credit Risk Financial instruments that potentially expose the Company to a concentration of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. The Company maintains cash, cash equivalents and marketable securities with financial institutions that management believes are financially sound and have minimal credit risk exposure although the balances will exceed insured limits. The Company sells its services to a wide variety of customers. If the financial condition or results of operations of any significant customers deteriorate substantially, operating results could be adversely affected. To reduce credit risk, management performs credit evaluations of the financial condition of significant customers. The Company does not require collateral from its credit customers and maintains reserves for estimated credit losses on customer accounts when considered necessary. Actual credit losses may differ from the Company’s estimates. During the three months ended March 31, 2021 and 2020, no customer organization accounted for more than 10% of the Company’s total revenue. As of March 31, 2021 and December 31, 2020, no customer organization represented more than 10% of the Company’s gross accounts receivable. (e) Significant Accounting Policies There have been no changes to the Company's significant accounting policies as described in its Annual Report. (f) Recently Issued Accounting Guidance, Not yet Adopted In August 2020, the FASB issued ASU 2020-06, “Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40),” which removes certain separation models for convertible debt instruments and convertible preferred stock that require the separation of a convertible debt instrument into a debt component and an equity or derivative component. The ASU also expands disclosure requirements for convertible instruments and simplifies areas of the guidance for diluted earnings-per-share calculations that are impacted by the amendments. The standard is effective for interim and annual periods beginning after December 15, 2021, with early adoption permitted. The Company is evaluating the impact of the adoption of this guidance on its consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Financial Assets The following tables provide the financial assets measured at fair value on a recurring basis: Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 1,867,034 $ — $ — $ 1,867,034 $ — $ — $ 1,867,034 Commercial paper 322,701 — — — 322,701 — 322,701 Total included in cash and cash equivalents 2,189,735 — — 1,867,034 322,701 — 2,189,735 Marketable securities: U.S. Treasury securities 236,651 248 (56) 236,843 — — 236,843 Corporate debt securities and commercial paper 3,134,407 5,582 (1,548) 45,000 3,093,441 — 3,138,441 Total marketable securities 3,371,058 5,830 (1,604) 281,843 3,093,441 — 3,375,284 Total financial assets $ 5,560,793 $ 5,830 $ (1,604) $ 2,148,877 $ 3,416,142 $ — $ 5,565,019 Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 656,749 $ — $ — $ 656,749 $ — $ — $ 656,749 Commercial paper 2,000 — — — 2,000 — 2,000 Total included in cash and cash equivalents 658,749 — — 656,749 2,000 — 658,749 Marketable securities: U.S. Treasury securities 223,247 389 (1) 223,635 — — 223,635 Corporate debt securities and commercial paper 1,874,257 8,149 (135) 50,000 1,832,271 — 1,882,271 Total marketable securities 2,097,504 8,538 (136) 273,635 1,832,271 — 2,105,906 Total financial assets $ 2,756,253 $ 8,538 $ (136) $ 930,384 $ 1,834,271 $ — $ 2,764,655 The Company's primary objective when investing excess cash is preservation of capital, hence the Company's marketable securities primarily consist of U.S. Treasury Securities, high credit quality corporate debt securities and commercial paper. As the Company views its marketable securities as available to support current operations, it has classified all available for sale securities as short-term. As of March 31, 2021 and December 31, 2020, for fixed income securities that were in unrealized loss positions, the Company has determined that (i) it does not have the intent to sell any of these investments, and (ii) it is not more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. In addition, as of March 31, 2021 and December 31, 2020, the Company anticipates that it will recover the entire amortized cost basis of such fixed income securities before maturity. The Company regularly reviews changes to the rating of its debt securities by rating agencies as well as reasonably monitors the surrounding economic conditions to assess the risk of expected credit losses. As of March 31, 2021, the risk of expected credit losses was not significant. Interest earned on marketable securities was $3.9 million and $8.8 million in the three months ended March 31, 2021 and 2020, respectively. The interest is recorded as other expenses, net, in the accompanying condensed consolidated statements of operations. The following table summarizes the contractual maturities of marketable securities: As of March 31, 2021 As of December 31, 2020 Amortized Aggregate Amortized Aggregate Financial Assets: (In thousands) Less than one year $ 1,322,778 $ 1,325,489 $ 1,126,091 $ 1,128,927 One to three years 2,048,280 2,049,795 971,413 976,979 Total $ 3,371,058 $ 3,375,284 $ 2,097,504 $ 2,105,906 Strategic Investments As of March 31, 2021 and December 31, 2020, the Company held strategic investments with a fair value of $9.3 million in equity securities of privately held companies in which the Company does not have a controlling interest or significant influence. These securities are recorded as other long-term assets in the accompanying condensed consolidated balance sheets. There were no impairments in the three months ended March 31, 2021 and 2020. Financial Liabilities The Company's financial liabilities that are not measured at fair value on a recurring basis consist of its convertible senior notes due 2023 (“Convertible Notes”) and its senior notes due 2029 and 2031 (“2029 Notes” and “2031 Notes,” respectively) that are further described in Note 9. As of March 31, 2021, the fair values of the Convertible Notes, 2029 Notes and 2031 Notes were $1.3 billion, $510.5 million and $512.8 million, respectively. The fair value of the Convertible Notes as of December 31, 2020 was $1.7 billion. The Convertible Notes, 2029 Notes and 2031 Notes are classified as level 2 financial instruments within the fair value hierarchy.

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) Capitalized internal-use software development costs $ 154,117 $ 142,489 Data center equipment (1) 49,627 43,477 Leasehold improvements 70,663 69,756 Office equipment 45,040 35,346 Furniture and fixtures (1) 12,808 12,312 Software 10,218 9,943 Total property and equipment 342,473 313,323 Less: accumulated depreciation and amortization (146,588) (130,084) Total property and equipment, net $ 195,885 $ 183,239 ____________________________________ ( 1 ) Data center equipment and furniture and fixtures contain assets under finance leases. See Note 5 for further detail. Depreciation and amortization expense was $14.4 million and $11.9 million for the three months ended March 31, 2021 and 2020, respectively.

Right-of-Use Asset and Lease Li

Right-of-Use Asset and Lease Liabilities	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Right-of-Use Asset and Lease Liabilities	Right-of-Use Asset and Lease Liabilities The Company has entered into various operating lease agreements for office space and data centers and finance lease agreements for data center and office equipment and furniture. As of March 31, 2021, the Company had 24 leased properties with remaining lease terms of 0.1 years to 8.0 years, some of which include options to extend the leases for up to 5.0 years. The components of the lease expense recorded in the accompanying condensed consolidated statements of operations were as follows: Three Months Ended 2021 2020 (In thousands) Operating lease cost $ 14,873 $ 10,424 Finance lease cost: Amortization of assets 2,680 1,904 Interest on lease liabilities 263 198 Short-term lease cost 1,692 1,412 Variable lease cost 2,900 1,296 Total net lease cost $ 22,408 $ 15,234 Supplemental balance sheet information related to leases was as follows: As of As of March 31, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 241,328 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 28,357 25,771 Total leased assets $ 269,685 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 46,239 $ 48,338 Finance Finance lease liability, current 9,389 9,062 Noncurrent Operating Operating lease liability, noncurrent 214,456 229,905 Finance Finance lease liability, noncurrent 19,933 17,856 Total lease liabilities $ 290,017 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $65.2 million and $57.1 million as of March 31, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $17.7 million and $15.0 million as of March 31, 2021 and December 31, 2020, respectively. Supplemental cash flow and other information related to leases was as follows: Three Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 14,691 $ 9,953 Operating cash flows from finance leases (interest) $ 263 $ 198 Financing cash flows from finance leases $ 2,748 $ 1,881 Weighted average remaining lease term (in years): Operating leases 5.9 5.8 Finance leases 3.4 2.9 Weighted average discount rate: Operating leases 4.8 % 5.7 % Finance leases 3.7 % 5.3 % Maturities of lease liabilities were as follows: As of March 31, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining nine months) $ 42,698 $ 7,911 2022 57,060 8,987 2023 48,937 8,240 2024 44,373 4,999 2025 32,167 547 Thereafter 75,304 518 Total lease payments 300,539 31,202 Less: imputed interest (39,844) (1,880) Total lease obligations 260,695 29,322 Less: current obligations (46,239) (9,389) Long-term lease obligations $ 214,456 $ 19,933 As of March 31, 2021, the Company had an additional operating lease obligation totaling $11.0 million for a lease that will commence in the first quarter of 2023 with a lease term of 6.2 years. As of March 31, 2021, the Company had no additional finance leases with future commencement dates.
Right-of-Use Asset and Lease Liabilities	Right-of-Use Asset and Lease Liabilities The Company has entered into various operating lease agreements for office space and data centers and finance lease agreements for data center and office equipment and furniture. As of March 31, 2021, the Company had 24 leased properties with remaining lease terms of 0.1 years to 8.0 years, some of which include options to extend the leases for up to 5.0 years. The components of the lease expense recorded in the accompanying condensed consolidated statements of operations were as follows: Three Months Ended 2021 2020 (In thousands) Operating lease cost $ 14,873 $ 10,424 Finance lease cost: Amortization of assets 2,680 1,904 Interest on lease liabilities 263 198 Short-term lease cost 1,692 1,412 Variable lease cost 2,900 1,296 Total net lease cost $ 22,408 $ 15,234 Supplemental balance sheet information related to leases was as follows: As of As of March 31, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 241,328 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 28,357 25,771 Total leased assets $ 269,685 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 46,239 $ 48,338 Finance Finance lease liability, current 9,389 9,062 Noncurrent Operating Operating lease liability, noncurrent 214,456 229,905 Finance Finance lease liability, noncurrent 19,933 17,856 Total lease liabilities $ 290,017 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $65.2 million and $57.1 million as of March 31, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $17.7 million and $15.0 million as of March 31, 2021 and December 31, 2020, respectively. Supplemental cash flow and other information related to leases was as follows: Three Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 14,691 $ 9,953 Operating cash flows from finance leases (interest) $ 263 $ 198 Financing cash flows from finance leases $ 2,748 $ 1,881 Weighted average remaining lease term (in years): Operating leases 5.9 5.8 Finance leases 3.4 2.9 Weighted average discount rate: Operating leases 4.8 % 5.7 % Finance leases 3.7 % 5.3 % Maturities of lease liabilities were as follows: As of March 31, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining nine months) $ 42,698 $ 7,911 2022 57,060 8,987 2023 48,937 8,240 2024 44,373 4,999 2025 32,167 547 Thereafter 75,304 518 Total lease payments 300,539 31,202 Less: imputed interest (39,844) (1,880) Total lease obligations 260,695 29,322 Less: current obligations (46,239) (9,389) Long-term lease obligations $ 214,456 $ 19,933 As of March 31, 2021, the Company had an additional operating lease obligation totaling $11.0 million for a lease that will commence in the first quarter of 2023 with a lease term of 6.2 years. As of March 31, 2021, the Company had no additional finance leases with future commencement dates.

Business Combinations

Business Combinations	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Business Combinations	Business Combinations On March 12, 2021, the Company acquired ValueFirst Digital Media Private Limited (“ValueFirst”) for a purchase price of $70.2 million paid in cash. ValueFirst is an enterprise communications platform in India. The acquisition was accounted for as a business combination and the preliminary purchase price was allocated to the net tangible and intangible assets as follows: Total (In thousands) Net tangible assets $ 9,756 Intangible assets (1) 30,300 Deferred tax liability (6,179) Goodwill 36,356 Total preliminary purchase price $ 70,233 ____________________________________ (1) Identifiable intangible assets were comprised of the following: Total Estimated (In thousands) (In years) Developed technology $ 6,700 7 Customer relationships 11,200 7 Carrier relationships 7,700 5 Trademark and trade name 4,700 5 Total intangible assets acquired $ 30,300 The acquired entity's results of operations were included in the Company's condensed consolidated financial statements from the date of the acquisition. Pro forma results of operations for this acquisition are not presented as the financial impact to the Company's consolidated financial statements is not material. As of March 31, 2021, the areas not yet finalized due to information that may become available subsequent to the filing of this Quarterly Report on Form 10-Q and may result in changes in the values recorded at March 31, 2021, relate to the purchase price, valuation of acquired intangible assets, contingencies and income and other taxes.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill The Goodwill balance as of March 31, 2021 and December 31, 2020, was as follows: Total (In thousands) Balance as of December 31, 2020 $ 4,595,394 Goodwill additions and adjustments 39,783 Balance as of March 31, 2021 $ 4,635,177 Intangible assets Intangible assets consisted of the following: As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 731,311 $ (139,293) $ 592,018 Customer relationships 390,564 (74,466) 316,098 Supplier relationships 12,071 (3,461) 8,610 Trade names 30,268 (9,252) 21,016 Order backlog 10,000 (4,167) 5,833 Patent 3,503 (409) 3,094 Total amortizable intangible assets 1,177,717 (231,048) 946,669 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,182,932 $ (231,048) $ 951,884 As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 724,599 $ (113,282) $ 611,317 Customer relationships 379,344 (59,574) 319,770 Supplier relationships 4,356 (3,044) 1,312 Trade name 25,560 (7,921) 17,639 Order backlog 10,000 (1,667) 8,333 Patent 3,360 (373) 2,987 Total amortizable intangible assets 1,147,219 (185,861) 961,358 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,152,434 $ (185,861) $ 966,573 Amortization expense was $45.2 million and $20.3 million for the three months ended March 31, 2021 and 2020, respectively. Total estimated future amortization expense is as follows: As of Year Ended December 31, (In thousands) 2021 (remaining nine months) $ 136,983 2022 172,264 2023 168,954 2024 163,380 2025 161,067 Thereafter 144,021 Total $ 946,669

Accrued Expenses and Other Liab

Accrued Expenses and Other Liabilities	3 Months Ended
	Mar. 31, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Accrued Expenses and Other Liabilities	Accrued Expenses and Other Liabilities Accrued expenses and other current liabilities consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) Accrued payroll and related $ 55,713 $ 54,683 Accrued bonus and commission 18,582 25,341 Accrued cost of revenue 88,882 80,620 Sales and other taxes payable 51,069 48,390 ESPP contributions 16,202 6,272 Finance lease liability, current 9,389 9,062 Accrued other expense 53,821 28,527 Total accrued expenses and other current liabilities $ 293,658 $ 252,895 Other long-term liabilities consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) Deferred tax liability $ 19,031 $ 13,684 Acquisition holdback 8,751 8,800 Accrued other expenses 14,842 14,149 Total other long-term liabilities $ 42,624 $ 36,633

Notes Payable

Notes Payable	3 Months Ended
	Mar. 31, 2021
Long-term Debt, Unclassified [Abstract]
Notes Payable	Notes Payable Long-term debt consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) 2029 Senior Notes (1) Principal $ 500,000 $ — Unamortized discount (6,209) — Unamortized issuance costs (1,213) — Net carrying amount 492,578 — 2031 Senior Notes (1) Principal 500,000 — Unamortized discount (6,219) — Unamortized issuance costs (1,216) — Net carrying amount 492,565 — Convertible Senior Notes (2) Principal 261,570 343,702 Unamortized discount (26,455) (38,406) Unamortized issuance costs (2,210) (3,228) Net carrying amount 232,905 302,068 Total long-term debt $ 1,218,048 $ 302,068 (1) 2029 and 2031 Senior Notes In March 2021, the Company issued $1.0 billion aggregate principal amount of senior notes, consisting of $500.0 million principal amount of 3.625% notes due 2029 (the “2029 Notes”) and $500.0 million principal amount of 3.875% notes due 2031 (the “2031 Notes,” and together with the 2029 Notes, the “Notes”). Initially, none of the Company's subsidiaries guaranteed the Notes. However, under certain circumstances in the future the Notes can be guaranteed by each of the Company's material domestic subsidiaries. The 2029 Notes and 2031 Notes will mature on March 15, 2029, and March 15, 2031, respectively. Interest payments are payable semi-annually in arrears on March 15 and September 15 of each year, commencing on September 15, 2021. The aggregate net proceeds from offering of the Notes were approximately $985.1 million, after deducting underwriting discounts and issuance costs, paid and payable by the Company. The issuance costs of $2.4 million will be amortized into interest expense using the effective interest method over the term of the Notes. The Company may voluntarily redeem the 2029 Notes, in whole or in part, under the following circumstances: (1) at any time prior to March 15, 2024 with the net cash proceeds received by the Company from an equity offering at a redemption price equal to 103.625% of the principal amount, provided the aggregate principal amount of all such redemptions does not exceed 40% of the original aggregate principal amount of the 2029 Notes. Such redemption shall occur within 180 days after the closing of an equity offering and at least 50% of the then-outstanding aggregate principal amount of the 2029 Notes shall remain outstanding, unless all 2029 Notes are redeemed concurrently; (2) at any time prior to March 15, 2024 at 100% of the principal amount, plus a “make-whole” premium; (3) at any time on or after March 15, 2024 at a prepayment price equal to 101.813% of the principal amount; (4) at any time on or after March 15, 2025 at a prepayment price equal to 100.906% of the principal amount; and (5) at any time on or after March 15, 2026 at a prepayment price equal to 100.000% of the principal amount; in each case, the redemption will include the accrued and unpaid interest, as applicable. The Company may voluntarily redeem the 2031 Notes, in whole or in part, under the following circumstances: (1) at any time prior to March 15, 2024 with the net cash proceeds received by the Company from an equity offering at a redemption price equal to 103.875% of the principal amount, provided the aggregate principal amount of all such redemptions does not to exceed 40% of the original aggregate principal amount of the 2031 Notes. Such redemption shall occur within 180 days after the closing of an equity offering and at least 50% of the then-outstanding aggregate principal amount of the 2031 Notes shall remain outstanding, unless all 2031 Notes are redeemed concurrently; (2) at any time prior to March 15, 2026 at 100% of the principal amount, plus a “make-whole” premium; (3) at any time on or after March 15, 2026 at a prepayment price equal to 101.938% of the principal amount; (4) at any time on or after March 15, 2027 at a prepayment price equal to 101.292% of the principal amount; (5) at any time on or after March 15, 2028 at a prepayment price equal to 100.646% of the principal amount; and (6) at any time on or after March 15, 2029 at a prepayment price equal to 100.000% of the principal amount; in each case, the redemption will include accrued and unpaid interest, as applicable. The Notes are unsecured obligations and will rank senior in right of payment to any of the Company’s indebtedness that is expressly subordinated in right of payment to the Notes that the Company may incur in the future and equal in right of payment with the Company’s existing and future liabilities that are not subordinated. In certain circumstances involving a change of control event, the Company will be required to make an offer to repurchase all, or, at the holder's option, any part, of each holder's notes of that series at 101% of the aggregate principal amount, plus accrued and unpaid interest, as applicable. The indenture governing the Notes (the “Indenture”) contains covenants limiting the Company's ability and the ability of its subsidiaries to: (i) create liens on certain assets to secure debt; (ii) grant a subsidiary guarantee of certain debt without also providing a guarantee of the Notes; and (iii) consolidate or merge with or into, or sell or otherwise dispose of all or substantially all of its assets to another person. These covenants are subject to a number of limitations and exceptions. Certain of these covenants will not apply during any period in which the Notes are rated investment grade by either Moody's Investors Service, Inc. or Standard & Poor's Ratings Services. For the three months ended March 31, 2021, the interest expense recognized related to the 2029 Notes and 2031 Notes was as follows: 2029 Notes 2031 Notes (In thousands) Contractual interest expense $ 1,120 $ 1,197 Amortization of debt discount and issuance costs 49 37 Total interest expense $ 1,169 $ 1,234 As of March 31, 2021, the Company was in compliance with all of its financial covenants under the Indenture. (2) Convertible Senior Notes and Capped Call Transactions In May 2018, the Company issued $550.0 million aggregate principal amount of 0.25% convertible senior notes due 2023 in a private placement, including $75.0 million aggregate principal amount of such Notes pursuant to the exercise in full of the over-allotment options of the initial purchasers (collectively, the “Convertible Notes”). The interest on the Convertible Notes is payable semi-annually in arrears on June 1 and December 1 of each year, beginning on December 1, 2018. The Convertible Notes may bear special interest under specified circumstances relating to the Company’s failure to comply with its reporting obligations under the indenture relating to the issuance of Convertible Notes (the “Convertible Notes Indenture”) or if the Convertible Notes are not freely tradeable as required by the Convertible Notes Indenture. The Convertible Notes will mature on June 1, 2023, unless earlier repurchased or redeemed by the Company or converted pursuant to their terms. The total net proceeds from the debt offering, after deducting initial purchaser discounts and debt issuance costs paid by us were approximately $537.0 million. Each $1,000 principal amount of the Convertible Notes is initially convertible into 14.104 shares of the Company’s Class A common stock par value $0.001, which is equivalent to an initial conversion price of approximately $70.90 per share. The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for any accrued and unpaid special interest. In addition, upon the occurrence of a make-whole fundamental change, as defined in the Convertible Notes Indenture, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its Convertible Notes in connection with such make-whole fundamental change or during the relevant redemption period. Prior to the close of business on the business day immediately preceding March 1, 2023, the Convertible Notes may be convertible at the option of the holders only under the following circumstances: (1) during any calendar quarter commencing after September 30, 2018, and only during such calendar quarter, if the last reported sale price of the Class A common stock for at least 20 trading days (whether or not consecutive) in a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is more than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business days period after any five consecutive trading day period in which, for each trading day of that period, the trading price per $1,000 principal amount of Convertible Notes for such trading day was less than 98% of the product of the last reported sale price of the Class A common stock and the conversion rate on each such trading day; (3) upon the Company’s notice that it is redeeming any or all of the Convertible Notes; or (4) upon the occurrence of specified corporate events. On or after March 1, 2023, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders of the Convertible Notes may, at their option, convert all or a portion of their Convertible Notes regardless of the foregoing conditions. Upon conversion, the Company may pay or deliver, as the case may be, cash, shares of Class A common stock, or a combination of cash and shares of Class A common stock, at the Company’s election. It is the Company’s current intent to settle the principal amount of the Convertible Notes in shares of Class A common stock if a conversion were to occur. During the three months ended March 31, 2021, the conditional conversion feature of the Convertible Notes was triggered as the last reported sale price of the Company's Class A common stock was more than or equal to 130% of the conversion price for at least 20 trading days (whether or not consecutive) in the period of 30 consecutive trading days ending on March 31, 2021 (the last trading day of the calendar quarter), and therefore the Convertible Notes are currently convertible, in whole or in part, at the option of the holders between April 1, 2021 through June 30, 2021. Whether the Convertible Notes will be convertible following such period will depend on the continued satisfaction of this condition or another conversion condition in the future. The Company continues to classify the Convertible Notes as a long-term liability in its condensed consolidated balance sheet as of March 31, 2021, based on contractual settlement provisions. The Company may redeem the Convertible Notes, in whole or in part, at its option, on or after June 1, 2021 but before the 35th scheduled trading day before the maturity date, at a cash redemption price equal to 100% of the principal amount of the Convertible Notes to be redeemed, plus accrued and unpaid interest, if any, if the last reported sale price of the Class A common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading days ending on, and including, the trading day immediately before the date the redemption notices were sent; and the trading day immediately before such notices were sent. No sinking fund is provided for the Convertible Notes. Upon the occurrence of a fundamental change (as defined in the Convertible Notes Indenture) prior to the maturity date, holders may require the Company to repurchase all or a portion of the Convertible Notes for cash at a price equal to 100% of the principal amount of the Convertible Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date. The Convertible Notes are senior unsecured obligations and will rank senior in right of payment to any of the Company’s indebtedness that is expressly subordinated in right of payment to the Convertible Notes; equal in right of payment with the Company’s existing and future liabilities that are not so subordinated; effectively subordinated to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness; and structurally junior to all indebtedness and other liabilities (including trade payables) of current or future subsidiaries of the Company. The foregoing description is qualified in its entirety by reference to the text of the Convertible Notes Indenture and the form of 0.25% convertible senior notes due 2023, which were filed as exhibits to the Company's Quarterly Report on Form 10-Q for the quarter ended June 30, 2018 and are incorporated herein by reference. In accounting for the issuance of the Convertible Notes, the Company separated the Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was $119.4 million and was determined by deducting the fair value of the liability component from the par value of the Convertible Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount, or the debt discount, is amortized to interest expense at an annual effective interest rate of 5.7% over the contractual terms of the Convertible Notes. In accounting for the transaction costs related to the Convertible Notes, the Company allocated the total amount incurred to the liability and equity components of the Convertible Notes based on the proportion of the proceeds allocated to the debt and equity components. Issuance costs attributable to the liability component were approximately $10.2 million, were recorded as an additional debt discount and are amortized to interest expense using the effective interest method over the contractual terms of the Convertible Notes. Issuance costs attributable to the equity component were netted with the equity component in stockholders’ equity. In the three months ended March 31, 2021, the Company converted $82.1 million aggregate principal amount of the Convertible Notes by issuing 1,158,381 shares of its Class A common stock. Of the $422.7 million total value of these transactions, $342.7 million and $80.1 million were allocated to the equity and liability components, respectively, utilizing an effective interest rate to determine the fair value of the liability component. The selected interest rate reflects the Company's incremental borrowing rate, adjusted for the Company's credit standing on nonconvertible debt with similar maturity. The extinguishment of these Convertible Notes resulted in a $7.6 million loss that is included in other expenses, net, in the accompanying condensed consolidated statement of operations. The net carrying amount of the equity component of the Convertible Notes was as follows: As of As of March 31, December 31, 2021 2020 (In thousands) Proceeds allocated to the conversion options (debt discount) $ 56,801 $ 74,636 Issuance costs (2,819) (2,819) Net carrying amount $ 53,982 $ 71,817 The following table sets forth the interest expense recognized related to the Convertible Notes: Three Months Ended 2021 2020 (In thousands) Contractual interest expense $ 170 $ 344 Amortization of debt issuance costs 259 484 Amortization of debt discount 3,028 5,694 Total interest expense $ 3,457 $ 6,522

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information A roll‑forward of the Company’s reserves is as follows: (a) Allowance for doubtful accounts: Three Months Ended 2021 2020 (In thousands) Balance, beginning of period $ 12,046 $ 6,287 Additions 3,381 4,261 Write-offs (2,036) (1,463) Balance, end of period $ 13,391 $ 9,085 Percentage of revenue 2 % 2 % (b) Customer credit reserve: Three Months Ended 2021 2020 (In thousands) Balance, beginning of period $ 16,783 $ 6,784 Additions 15,466 8,174 Deductions against reserve (14,998) (5,271) Balance, end of period $ 17,251 $ 9,687 Percentage of revenue 3 % 3 %

Revenue by Geographic Area

Revenue by Geographic Area	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Revenue by Geographic Area	Revenue by Geographic Area Revenue by geographic area is based on the IP address or the mailing address at the time of registration. The following table sets forth revenue by geographic area: Three Months Ended 2021 2020 Revenue by geographic area: (In thousands) United States $ 421,531 $ 261,813 International 168,457 103,055 Total $ 589,988 $ 364,868 Percentage of revenue by geographic area: United States 71 % 72 % International 29 % 28 % Long-lived assets outside of the United States were not significant.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and ContingenciesLease and Other Commitments The Company entered into various non-cancelable operating lease agreements for its facilities with remaining lease terms from less than one year to eight years. See Note 5 to these condensed consolidated financial statements for additional detail on the Company's operating and finance lease commitments. Additionally, the Company has noncancellable contractual commitments with its cloud infrastructure provider, network service providers and other vendors. In the three months ended March 31, 2021, the Company entered into several such agreements with terms up to three years for a total purchase commitment of $426.9 million. In February 2021, the Company entered into a Framework Agreement with Syniverse Corporation (“Syniverse”) and Carlyle Partners V Holdings, L.P. (“Carlyle”) (the “Framework Agreement”), pursuant to which Syniverse will issue to the Company shares of Syniverse common stock in consideration for an investment by the Company of up to $750.0 million. In connection with the closing of the investment, the Company and Syniverse will enter into a wholesale agreement, in which Syniverse will process, route and deliver application-to-person messages originating and/or terminating between the Company's customers and mobile network operators. The investment is expected to result in the Company holding a significant minority equity ownership position in Syniverse, subject to certain adjustments based on the terms of the final agreement. This proposed transaction closing is subject to consummation of certain other transactions by Syniverse, as defined in the Framework Agreement, and other customary closing conditions, including regulatory approvals. The closing is expected to occur before the end of 2021. As of March 31, 2021, the Company has deferred $3.3 million of costs related to this proposed transaction that are recorded in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheet. From time to time, the Company may be subject to legal actions and claims in the ordinary course of business. The Company has received, and may in the future continue to receive, claims from third parties asserting, among other things, infringement of their intellectual property rights. Future litigation may be necessary to defend the Company, its partners and its customers by determining the scope, enforceability and validity of third‑party proprietary rights, or to establish our proprietary rights. The results of any current or future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources, and other factors. Legal fees and other costs related to litigation and other legal proceedings are expensed as incurred and are included in general and administrative expenses in the accompanying condensed consolidated statements of operations. The Company has signed indemnification agreements with all of its board members and executive officers. The agreements indemnify the board members and executive officers from claims and expenses on actions brought against the individuals separately or jointly with the Company for certain indemnifiable events. Indemnifiable events generally mean any event or occurrence related to the fact that the board member or the executive officer was or is acting in his or her capacity as a board member or an executive officer for the Company or was or is acting or representing the interests of the Company. In the ordinary course of business and in connection with our financing and business combinations transactions, the Company enters into contractual arrangements under which it agrees to provide indemnification of varying scope and terms to business partners, customers and other parties with respect to certain matters, including, but not limited to, losses arising out of the breach of such agreements, intellectual property infringement claims made by third parties and other liabilities relating to or arising from the Company’s various products, or its acts or omissions. In these circumstances, payment may be conditional on the other party making a claim pursuant to the procedures specified in the particular contract. Further, the Company’s obligations under these agreements may be limited in terms of time and/or amount, and in some instances, the Company may have recourse against third parties for certain payments. The terms of such obligations may vary. As of March 31, 2021 and December 31, 2020, no amounts were accrued related to any outstanding indemnification agreements. The Company conducts operations in many tax jurisdictions within and outside the United States. In many of these jurisdictions, non-income-based taxes, such as sales, use, telecommunications, and other local taxes are assessed on the Company’s operations. Prior to March 2017, the Company had not billed nor collected these taxes from its customers and, in accordance with U.S. GAAP, recorded a provision for its tax exposure in these jurisdictions when it was both probable that a liability had been incurred and the amount of the exposure could be reasonably estimated. These estimates included several key assumptions including, but not limited to, the taxability of the Company’s services, the jurisdictions in which its management believes it had nexus, and the sourcing of revenues to those jurisdictions. Starting in March 2017, the Company began collecting these taxes from customers in certain jurisdictions and since then has expanded to collect taxes in most jurisdictions where the Company operates. The Company is also in discussions with certain jurisdictions regarding its prior sales and other taxes, if any, that it may owe. In the event any of these jurisdictions disagrees with management’s assumptions and analysis, the assessment of the Company's tax exposure could differ materially from management's current estimates. For example, one jurisdiction has assessed the Company for $38.8 million in taxes, including interest and penalties, which exceeded the $11.5 million the Company had accrued for the period covered by this assessment. The Company believes that this assessment is incorrect and has disputed it, paid the full amount as required by law, and is seeking a refund or settlement. The payment made in excess of the accrued amount is reflected as a deposit in the Company's accompanying condensed consolidated balance sheets. If a reasonable settlement cannot be reached in the near future, the Company will challenge the jurisdiction’s assessment in court. However, litigation is uncertain and a ruling against the Company may adversely affect its financial position and results of operation. As of March 31, 2021 and December 31, 2020, the liability recorded for these taxes was $26.6 million and $25.6 million, respectively.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock As of March 31, 2021 and December 31, 2020, the Company had authorized 100,000,000 shares of preferred stock, par value $0.001, of which no shares were issued and outstanding. Common Stock As of March 31, 2021 and December 31, 2020, the Company had authorized 1,000,000,000 shares of Class A common stock and 100,000,000 shares of Class B common stock, each par value $0.001 per share. As of March 31, 2021, 160,588,258 shares of Class A common stock and 10,343,302 shares of Class B common stock were issued and outstanding. As of December 31, 2020, 153,496,222 shares of Class A common stock and 10,551,302 shares of Class B common stock were issued and outstanding. Holders of Class A and Class B common stock are entitled to one vote per share and 10 votes per share, respectively, and the shares of Class A common stock and Class B common stock are identical, except for voting and conversion rights. The Company had reserved shares of common stock for issuance as follows: As of As of March 31, December 31, 2021 2020 Stock options issued and outstanding 5,216,385 5,625,735 Unvested restricted stock units issued and outstanding 6,758,222 7,523,882 Class A common stock reserved for Twilio.org 685,163 707,265 Stock-based awards available for grant under 2016 Plan 26,871,942 18,942,205 Stock-based awards available for grant under 2016 ESPP 6,581,756 4,941,281 Class A common stock reserved for the convertible senior notes 6,411,350 7,569,731 Total 52,524,818 45,310,099 Public Equity Offerings In February 2021, the Company completed public equity offerings in which it sold 4,312,500 shares of its Class A common stock at a public offering price of $409.60 per share. The Company received total proceeds of $1.8 billion, net of offering expenses paid and payable by the Company.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company's 2016 Stock Option and Incentive Plan (the “2016 Plan”) provides for granting stock options, restricted stock units ("RSU"), restricted stock awards (“RSA”), stock appreciation rights, unrestricted stock awards, performance share awards, dividend equivalent rights and cash-based awards to its employees, directors and consultants. Certain of the Company's outstanding equity awards were granted under equity incentive plans that are no longer active but continue to govern the outstanding equity awards granted thereunder. The Company also offers an Employee Stock Purchase Plan ("ESPP") to eligible employees. The ESPP provides for separate six-month offering periods beginning in May and November of each year. On January 1, 2021, the shares available for grant under the 2016 Plan and ESPP were automatically increased by 8,202,376 shares and 1,640,475 shares, respectively. Stock-options and restricted stock units and awards activity under the Company's equity incentive plans was as follows: Stock Options Number of Weighted- Weighted- Aggregate Outstanding options as of December 31, 2020 5,070,735 $ 51.71 6.85 $ 1,454,222 Granted 108,429 378.11 Exercised (459,379) 25.17 Forfeited and canceled (58,400) 62.63 Outstanding options as of March 31, 2021 4,661,385 $ 61.78 6.67 $ 1,304,466 Options vested and exercisable as of March 31, 2021 2,609,089 $ 26.89 5.35 $ 818,926 Three Months Ended 2021 2020 (In thousands, except per share amounts) Aggregate intrinsic value of stock options exercised (1) $ 165,559 $ 68,359 Total estimated grant date fair value of options vested $ 31,979 $ 23,335 Weighted-average grant date fair value per share of options granted $ 205.36 $ 60.47 ____________________________________ ( 1 ) Aggregate intrinsic value represents the difference between the fair value of the Company’s Class A common stock as reported on the New York Stock Exchange and the exercise price of outstanding “in-the-money” options. Additionally, as of March 31, 2021, the Company had outstanding 555,000 shares of performance-based stock options with a weighted average exercise price of $31.72, of which 543,437 were vested and exercisable. All performance conditions have been met. Restricted Stock Units and Awards Number of Weighted- Aggregate Unvested RSUs as of December 31, 2020 7,523,882 $ 131.76 $ 2,542,858 Granted 314,291 389.26 Vested (919,022) 84.12 Forfeited and canceled (160,929) 124.66 Unvested RSUs as of March 31, 2021 6,758,222 $ 150.39 $ 2,302,932 Additionally, as of March 31, 2021, the Company granted 24,697 shares of RSAs with a weighted average grant date fair value of $359.80 per share and aggregate intrinsic value of $8.9 million. As of March 31, 2021, the Company had 258,554 shares of its Class A common stock in escrow that are subject to future vesting over a period of 2.5 years with a weighted average grant date fair value of $273.38 per share and aggregate intrinsic value of $88.1 million. As of March 31, 2021, total unrecognized compensation cost was as follows: Unrecognized Compensation Cost Weighted-average remaining period (In thousands) (In years) Unvested stock options $ 225,119 2.4 Unvested restricted stock units and awards 923,508 2.9 Class A shares in escrow subject to future vesting 58,889 2.5 ESPP 2,119 0.1 Total $ 1,209,635 Valuation Assumptions The fair value of employee stock options was estimated on the date of grant using the following assumptions in the Black-Scholes option pricing model: Three Months Ended Employee Stock Options: 2021 2020 Fair value of common stock $377.6 - $409.2 $117.9 - $126.7 Expected term (in years) 6.08 6.08 Expected volatility 58.3% - 58.4% 51.9% Risk-free interest rate 0.8% - 1.0% 1.3% - 1.4% Dividend rate —% —% Stock-Based Compensation Expense The Company recorded total stock-based compensation expense as follows: Three Months Ended 2021 2020 (In thousands) Cost of revenue $ 2,717 $ 1,837 Research and development 56,959 33,209 Sales and marketing 41,636 19,943 General and administrative 35,843 14,036 Total $ 137,155 $ 69,025

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common StockholdersBasic and diluted net loss per common share is presented in conformity with the two-class method required for participating securities and is described in detail in the Company's Annual Report. The following table sets forth the calculation of basic and diluted net loss per share attributable to common stockholders during the periods presented: Three Months Ended 2021 2020 Net loss attributable to common stockholders (in thousands) $ (206,542) $ (94,791) Weighted-average shares used to compute net loss per share attributable to 167,160,458 139,231,594 Net loss per share attributable to common stockholders, basic and diluted $ (1.24) $ (0.68) The following outstanding shares of common stock equivalents were excluded from the calculation of the diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive: As of March 31, 2021 2020 Stock options issued and outstanding 5,216,385 7,492,970 Restricted stock units issued and outstanding 6,758,222 8,039,823 Class A common stock reserved for Twilio.org 685,163 773,571 Class A common stock committed under 2016 ESPP 101,030 212,028 Convertible senior notes (1) 3,689,177 2,747,996 Class A common stock in escrow 75,612 — Class A common stock in escrow and restricted stock awards subject to future 289,618 — Total 16,815,207 19,266,388 ____________________________________

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes        The Company computes its provision for interim periods by applying an estimated annual effective tax rate to anticipated annual pretax income or loss. The estimated annual effective tax rate is applied to the Company's year to date income or loss, and is adjusted for discrete items recorded in the period. The Company recorded an income tax provision of $0.9 million and $1.0 million for the three months ended March 31, 2021 and 2020, respectively. The provision for income taxes recorded in the three months ended March 31, 2021 and 2020 consists primarily of income taxes and withholding taxes in foreign jurisdictions in which the Company conducts business, partially offset by an income tax benefit from the reversal of U.S. deferred tax liabilities related to acquired intangibles from prior year business combinations. The primary difference between the effective tax rate and the federal statutory rate is the full valuation allowance the Company established on the federal, state, and certain foreign net operating losses and credits. The Company continues to maintain a full valuation allowance against its U.S. federal and state net deferred tax assets.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. Therefore, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes included in the Company's Annual Report on Form 10-K filed with the SEC on February 26, 2021 (“Annual Report”). The condensed consolidated balance sheet as of December 31, 2020, included herein, was derived from the audited financial statements as of that date, but may not include all disclosures including certain notes required by U.S. GAAP on an annual reporting basis. In the opinion of management, the accompanying condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the financial position, results of operations, comprehensive loss, stockholders' equity and cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full year 2021 or any future period.
Principles of Consolidation	Principles of ConsolidationThe condensed consolidated financial statements include the Company and its wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated.
Use of Estimates	Use of EstimatesThe preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. These estimates are used for, but not limited to, revenue allowances and sales credit reserves; recoverability of long-lived and intangible assets; capitalization and useful life of the Company’s capitalized internal-use software development costs; fair value of acquired intangible assets and goodwill; accruals and contingencies. Estimates are based on historical experience and on various assumptions that the Company believes are reasonable under current circumstances. However, future events are subject to change and best estimates and judgments may require further adjustments, therefore, actual results could differ materially from those estimates. Management periodically evaluates such estimates and they are adjusted prospectively based upon such periodic evaluation.
Concentration of Credit Risk	Concentration of Credit RiskFinancial instruments that potentially expose the Company to a concentration of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. The Company maintains cash, cash equivalents and marketable securities with financial institutions that management believes are financially sound and have minimal credit risk exposure although the balances will exceed insured limits.The Company sells its services to a wide variety of customers. If the financial condition or results of operations of any significant customers deteriorate substantially, operating results could be adversely affected. To reduce credit risk, management performs credit evaluations of the financial condition of significant customers. The Company does not require collateral from its credit customers and maintains reserves for estimated credit losses on customer accounts when considered necessary. Actual credit losses may differ from the Company’s estimates.
Recently Issued Accounting Guidance, Not yet Adopted	Recently Issued Accounting Guidance, Not yet Adopted In August 2020, the FASB issued ASU 2020-06, “Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40),” which removes certain separation models for convertible debt instruments and convertible preferred stock that require the separation of a convertible debt instrument into a debt component and an equity or derivative component. The ASU also expands disclosure requirements for convertible instruments and simplifies areas of the guidance for diluted earnings-per-share calculations that are impacted by the amendments. The standard is effective for interim and annual periods beginning after December 15, 2021, with early adoption permitted. The Company is evaluating the impact of the adoption of this guidance on its consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of financial assets measured at fair value on a recurring basis	The following tables provide the financial assets measured at fair value on a recurring basis: Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 1,867,034 $ — $ — $ 1,867,034 $ — $ — $ 1,867,034 Commercial paper 322,701 — — — 322,701 — 322,701 Total included in cash and cash equivalents 2,189,735 — — 1,867,034 322,701 — 2,189,735 Marketable securities: U.S. Treasury securities 236,651 248 (56) 236,843 — — 236,843 Corporate debt securities and commercial paper 3,134,407 5,582 (1,548) 45,000 3,093,441 — 3,138,441 Total marketable securities 3,371,058 5,830 (1,604) 281,843 3,093,441 — 3,375,284 Total financial assets $ 5,560,793 $ 5,830 $ (1,604) $ 2,148,877 $ 3,416,142 $ — $ 5,565,019 Amortized Gross Gross Fair Value Hierarchy as of Aggregate Level 1 Level 2 Level 3 Financial Assets: (In thousands) Cash and cash equivalents: Money market funds $ 656,749 $ — $ — $ 656,749 $ — $ — $ 656,749 Commercial paper 2,000 — — — 2,000 — 2,000 Total included in cash and cash equivalents 658,749 — — 656,749 2,000 — 658,749 Marketable securities: U.S. Treasury securities 223,247 389 (1) 223,635 — — 223,635 Corporate debt securities and commercial paper 1,874,257 8,149 (135) 50,000 1,832,271 — 1,882,271 Total marketable securities 2,097,504 8,538 (136) 273,635 1,832,271 — 2,105,906 Total financial assets $ 2,756,253 $ 8,538 $ (136) $ 930,384 $ 1,834,271 $ — $ 2,764,655
Schedule of contractual maturities of marketable securities	The following table summarizes the contractual maturities of marketable securities: As of March 31, 2021 As of December 31, 2020 Amortized Aggregate Amortized Aggregate Financial Assets: (In thousands) Less than one year $ 1,322,778 $ 1,325,489 $ 1,126,091 $ 1,128,927 One to three years 2,048,280 2,049,795 971,413 976,979 Total $ 3,371,058 $ 3,375,284 $ 2,097,504 $ 2,105,906

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	Property and equipment consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) Capitalized internal-use software development costs $ 154,117 $ 142,489 Data center equipment (1) 49,627 43,477 Leasehold improvements 70,663 69,756 Office equipment 45,040 35,346 Furniture and fixtures (1) 12,808 12,312 Software 10,218 9,943 Total property and equipment 342,473 313,323 Less: accumulated depreciation and amortization (146,588) (130,084) Total property and equipment, net $ 195,885 $ 183,239 ____________________________________ ( 1 ) Data center equipment and furniture and fixtures contain assets under finance leases. See Note 5 for further detail.

Right-of-Use Asset and Lease _2

Right-of-Use Asset and Lease Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Leases [Abstract]
Lease, Cost	The components of the lease expense recorded in the accompanying condensed consolidated statements of operations were as follows: Three Months Ended 2021 2020 (In thousands) Operating lease cost $ 14,873 $ 10,424 Finance lease cost: Amortization of assets 2,680 1,904 Interest on lease liabilities 263 198 Short-term lease cost 1,692 1,412 Variable lease cost 2,900 1,296 Total net lease cost $ 22,408 $ 15,234 Supplemental cash flow and other information related to leases was as follows: Three Months Ended 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: (In thousands) Operating cash flows from operating leases $ 14,691 $ 9,953 Operating cash flows from finance leases (interest) $ 263 $ 198 Financing cash flows from finance leases $ 2,748 $ 1,881 Weighted average remaining lease term (in years): Operating leases 5.9 5.8 Finance leases 3.4 2.9 Weighted average discount rate: Operating leases 4.8 % 5.7 % Finance leases 3.7 % 5.3 %
Assets and Liabilities, Lessee	Supplemental balance sheet information related to leases was as follows: As of As of March 31, December 31, Leases Classification 2021 2020 Assets: (In thousands) Operating lease assets Operating right-of-use asset, net of accumulated amortization (1) $ 241,328 $ 258,610 Finance lease assets Property and equipment, net of accumulated depreciation (2) 28,357 25,771 Total leased assets $ 269,685 $ 284,381 Liabilities: Current Operating Operating lease liability, current $ 46,239 $ 48,338 Finance Finance lease liability, current 9,389 9,062 Noncurrent Operating Operating lease liability, noncurrent 214,456 229,905 Finance Finance lease liability, noncurrent 19,933 17,856 Total lease liabilities $ 290,017 $ 305,161 ____________________________________ (1) Operating lease assets are recorded net of accumulated amortization of $65.2 million and $57.1 million as of March 31, 2021 and December 31, 2020, respectively. (2) Finance lease assets are recorded net of accumulated depreciation of $17.7 million and $15.0 million as of March 31, 2021 and December 31, 2020, respectively.
Lessee, Operating Lease, Liability, Maturity	Maturities of lease liabilities were as follows: As of March 31, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining nine months) $ 42,698 $ 7,911 2022 57,060 8,987 2023 48,937 8,240 2024 44,373 4,999 2025 32,167 547 Thereafter 75,304 518 Total lease payments 300,539 31,202 Less: imputed interest (39,844) (1,880) Total lease obligations 260,695 29,322 Less: current obligations (46,239) (9,389) Long-term lease obligations $ 214,456 $ 19,933
Finance Lease, Liability, Maturity	Maturities of lease liabilities were as follows: As of March 31, 2021 Operating Finance Year Ended December 31, (In thousands) 2021 (remaining nine months) $ 42,698 $ 7,911 2022 57,060 8,987 2023 48,937 8,240 2024 44,373 4,999 2025 32,167 547 Thereafter 75,304 518 Total lease payments 300,539 31,202 Less: imputed interest (39,844) (1,880) Total lease obligations 260,695 29,322 Less: current obligations (46,239) (9,389) Long-term lease obligations $ 214,456 $ 19,933

Business Combinations (Tables)

Business Combinations (Tables)	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Schedule of purchase price allocation	Total (In thousands) Net tangible assets $ 9,756 Intangible assets (1) 30,300 Deferred tax liability (6,179) Goodwill 36,356 Total preliminary purchase price $ 70,233 ____________________________________ (1) Identifiable intangible assets were comprised of the following: Total Estimated (In thousands) (In years) Developed technology $ 6,700 7 Customer relationships 11,200 7 Carrier relationships 7,700 5 Trademark and trade name 4,700 5 Total intangible assets acquired $ 30,300
Schedule of identifiable finite-lived intangible assets	(1) Identifiable intangible assets were comprised of the following: Total Estimated (In thousands) (In years) Developed technology $ 6,700 7 Customer relationships 11,200 7 Carrier relationships 7,700 5 Trademark and trade name 4,700 5 Total intangible assets acquired $ 30,300

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill balance	Goodwill balance as of March 31, 2021 and December 31, 2020, was as follows: Total (In thousands) Balance as of December 31, 2020 $ 4,595,394 Goodwill additions and adjustments 39,783 Balance as of March 31, 2021 $ 4,635,177
Schedule of intangible assets	Intangible assets consisted of the following: As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 731,311 $ (139,293) $ 592,018 Customer relationships 390,564 (74,466) 316,098 Supplier relationships 12,071 (3,461) 8,610 Trade names 30,268 (9,252) 21,016 Order backlog 10,000 (4,167) 5,833 Patent 3,503 (409) 3,094 Total amortizable intangible assets 1,177,717 (231,048) 946,669 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,182,932 $ (231,048) $ 951,884 As of Gross Accumulated Net Amortizable intangible assets: (In thousands) Developed technology $ 724,599 $ (113,282) $ 611,317 Customer relationships 379,344 (59,574) 319,770 Supplier relationships 4,356 (3,044) 1,312 Trade name 25,560 (7,921) 17,639 Order backlog 10,000 (1,667) 8,333 Patent 3,360 (373) 2,987 Total amortizable intangible assets 1,147,219 (185,861) 961,358 Non-amortizable intangible assets: Telecommunication licenses 4,920 — 4,920 Trademarks and other 295 — 295 Total $ 1,152,434 $ (185,861) $ 966,573
Schedule of total estimated future amortization expense	Total estimated future amortization expense is as follows: As of Year Ended December 31, (In thousands) 2021 (remaining nine months) $ 136,983 2022 172,264 2023 168,954 2024 163,380 2025 161,067 Thereafter 144,021 Total $ 946,669

Accrued Expenses and Other Li_2

Accrued Expenses and Other Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Accrued Liabilities and Other Liabilities [Abstract]
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) Accrued payroll and related $ 55,713 $ 54,683 Accrued bonus and commission 18,582 25,341 Accrued cost of revenue 88,882 80,620 Sales and other taxes payable 51,069 48,390 ESPP contributions 16,202 6,272 Finance lease liability, current 9,389 9,062 Accrued other expense 53,821 28,527 Total accrued expenses and other current liabilities $ 293,658 $ 252,895
Schedule of other long-term liabilities	Other long-term liabilities consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) Deferred tax liability $ 19,031 $ 13,684 Acquisition holdback 8,751 8,800 Accrued other expenses 14,842 14,149 Total other long-term liabilities $ 42,624 $ 36,633

Notes Payable (Tables)

Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2021
Long-term Debt, Unclassified [Abstract]
Schedule of net carrying amount of the liability and equity components of the Notes	Long-term debt consisted of the following: As of As of March 31, December 31, 2021 2020 (In thousands) 2029 Senior Notes (1) Principal $ 500,000 $ — Unamortized discount (6,209) — Unamortized issuance costs (1,213) — Net carrying amount 492,578 — 2031 Senior Notes (1) Principal 500,000 — Unamortized discount (6,219) — Unamortized issuance costs (1,216) — Net carrying amount 492,565 — Convertible Senior Notes (2) Principal 261,570 343,702 Unamortized discount (26,455) (38,406) Unamortized issuance costs (2,210) (3,228) Net carrying amount 232,905 302,068 Total long-term debt $ 1,218,048 $ 302,068 The net carrying amount of the equity component of the Convertible Notes was as follows: As of As of March 31, December 31, 2021 2020 (In thousands) Proceeds allocated to the conversion options (debt discount) $ 56,801 $ 74,636 Issuance costs (2,819) (2,819) Net carrying amount $ 53,982 $ 71,817
Schedule of interest expense recognized related to the Notes	For the three months ended March 31, 2021, the interest expense recognized related to the 2029 Notes and 2031 Notes was as follows: 2029 Notes 2031 Notes (In thousands) Contractual interest expense $ 1,120 $ 1,197 Amortization of debt discount and issuance costs 49 37 Total interest expense $ 1,169 $ 1,234 The following table sets forth the interest expense recognized related to the Convertible Notes: Three Months Ended 2021 2020 (In thousands) Contractual interest expense $ 170 $ 344 Amortization of debt issuance costs 259 484 Amortization of debt discount 3,028 5,694 Total interest expense $ 3,457 $ 6,522

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	3 Months Ended
	Mar. 31, 2021
Receivables [Abstract]
Schedule of the allowance for doubtful accounts	Allowance for doubtful accounts: Three Months Ended 2021 2020 (In thousands) Balance, beginning of period $ 12,046 $ 6,287 Additions 3,381 4,261 Write-offs (2,036) (1,463) Balance, end of period $ 13,391 $ 9,085 Percentage of revenue 2 % 2 %
Schedule of the sales credit reserve	Customer credit reserve: Three Months Ended 2021 2020 (In thousands) Balance, beginning of period $ 16,783 $ 6,784 Additions 15,466 8,174 Deductions against reserve (14,998) (5,271) Balance, end of period $ 17,251 $ 9,687 Percentage of revenue 3 % 3 %

Revenue by Geographic Area (Tab

Revenue by Geographic Area (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Schedule of revenue by geographic area	Revenue by geographic area is based on the IP address or the mailing address at the time of registration. The following table sets forth revenue by geographic area: Three Months Ended 2021 2020 Revenue by geographic area: (In thousands) United States $ 421,531 $ 261,813 International 168,457 103,055 Total $ 589,988 $ 364,868 Percentage of revenue by geographic area: United States 71 % 72 % International 29 % 28 %

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Stockholders' Equity Note [Abstract]
Schedule of reserved shares of common stock for issuance	The Company had reserved shares of common stock for issuance as follows: As of As of March 31, December 31, 2021 2020 Stock options issued and outstanding 5,216,385 5,625,735 Unvested restricted stock units issued and outstanding 6,758,222 7,523,882 Class A common stock reserved for Twilio.org 685,163 707,265 Stock-based awards available for grant under 2016 Plan 26,871,942 18,942,205 Stock-based awards available for grant under 2016 ESPP 6,581,756 4,941,281 Class A common stock reserved for the convertible senior notes 6,411,350 7,569,731 Total 52,524,818 45,310,099 Public Equity Offerings In February 2021, the Company completed public equity offerings in which it sold 4,312,500 shares of its Class A common stock at a public offering price of $409.60 per share. The Company received total proceeds of $1.8 billion, net of offering expenses paid and payable by the Company.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Schedule of stock options activity	Number of Weighted- Weighted- Aggregate Outstanding options as of December 31, 2020 5,070,735 $ 51.71 6.85 $ 1,454,222 Granted 108,429 378.11 Exercised (459,379) 25.17 Forfeited and canceled (58,400) 62.63 Outstanding options as of March 31, 2021 4,661,385 $ 61.78 6.67 $ 1,304,466 Options vested and exercisable as of March 31, 2021 2,609,089 $ 26.89 5.35 $ 818,926
Schedule of weighted average grant date fair value	Three Months Ended 2021 2020 (In thousands, except per share amounts) Aggregate intrinsic value of stock options exercised (1) $ 165,559 $ 68,359 Total estimated grant date fair value of options vested $ 31,979 $ 23,335 Weighted-average grant date fair value per share of options granted $ 205.36 $ 60.47 ____________________________________ ( 1 ) Aggregate intrinsic value represents the difference between the fair value of the Company’s Class A common stock as reported on the New York Stock Exchange and the exercise price of outstanding “in-the-money” options.
Schedule of restricted stock unit activity	Number of Weighted- Aggregate Unvested RSUs as of December 31, 2020 7,523,882 $ 131.76 $ 2,542,858 Granted 314,291 389.26 Vested (919,022) 84.12 Forfeited and canceled (160,929) 124.66 Unvested RSUs as of March 31, 2021 6,758,222 $ 150.39 $ 2,302,932
Schedule of unrecognized compensation	As of March 31, 2021, total unrecognized compensation cost was as follows: Unrecognized Compensation Cost Weighted-average remaining period (In thousands) (In years) Unvested stock options $ 225,119 2.4 Unvested restricted stock units and awards 923,508 2.9 Class A shares in escrow subject to future vesting 58,889 2.5 ESPP 2,119 0.1 Total $ 1,209,635
Schedule of valuation assumptions, options	The fair value of employee stock options was estimated on the date of grant using the following assumptions in the Black-Scholes option pricing model: Three Months Ended Employee Stock Options: 2021 2020 Fair value of common stock $377.6 - $409.2 $117.9 - $126.7 Expected term (in years) 6.08 6.08 Expected volatility 58.3% - 58.4% 51.9% Risk-free interest rate 0.8% - 1.0% 1.3% - 1.4% Dividend rate —% —%
Schedule of stock based compensation expense	The Company recorded total stock-based compensation expense as follows: Three Months Ended 2021 2020 (In thousands) Cost of revenue $ 2,717 $ 1,837 Research and development 56,959 33,209 Sales and marketing 41,636 19,943 General and administrative 35,843 14,036 Total $ 137,155 $ 69,025

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of the calculation of basic and diluted net loss per share attributable to common stockholders	The following table sets forth the calculation of basic and diluted net loss per share attributable to common stockholders during the periods presented: Three Months Ended 2021 2020 Net loss attributable to common stockholders (in thousands) $ (206,542) $ (94,791) Weighted-average shares used to compute net loss per share attributable to 167,160,458 139,231,594 Net loss per share attributable to common stockholders, basic and diluted $ (1.24) $ (0.68)
Schedule of common stock equivalents excluded from the computation of the diluted net loss per share attributable to common stockholders	The following outstanding shares of common stock equivalents were excluded from the calculation of the diluted net loss per share attributable to common stockholders because their effect would have been anti-dilutive: As of March 31, 2021 2020 Stock options issued and outstanding 5,216,385 7,492,970 Restricted stock units issued and outstanding 6,758,222 8,039,823 Class A common stock reserved for Twilio.org 685,163 773,571 Class A common stock committed under 2016 ESPP 101,030 212,028 Convertible senior notes (1) 3,689,177 2,747,996 Class A common stock in escrow 75,612 — Class A common stock in escrow and restricted stock awards subject to future 289,618 — Total 16,815,207 19,266,388 ____________________________________

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	$ 2,189,735	$ 658,749
Total amortized cost	3,371,058	2,097,504
Gross Unrealized Gains	5,830	8,538
Gross Unrealized Losses	(1,604)	(136)
Marketable securities, aggregate fair value	3,375,284	2,105,906
Financial Assets, Amortized Cost or Carrying Value	5,560,793	2,756,253
Total financial assets	5,565,019	2,764,655
Note receivable	9,300	9,300
U.S. Treasury securities
Fair Value Measurements, Financial Assets
Total amortized cost	236,651	223,247
Gross Unrealized Gains	248	389
Gross Unrealized Losses	(56)	(1)
Marketable securities, aggregate fair value	236,843	223,635
Corporate debt securities and commercial paper
Fair Value Measurements, Financial Assets
Total amortized cost	3,134,407	1,874,257
Gross Unrealized Gains	5,582	8,149
Gross Unrealized Losses	(1,548)	(135)
Marketable securities, aggregate fair value	3,138,441	1,882,271
Level 1
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	1,867,034	656,749
Marketable securities, aggregate fair value	281,843	273,635
Total financial assets	2,148,877	930,384
Level 1 | U.S. Treasury securities
Fair Value Measurements, Financial Assets
Marketable securities, aggregate fair value	236,843	223,635
Level 1 | Corporate debt securities and commercial paper
Fair Value Measurements, Financial Assets
Marketable securities, aggregate fair value	45,000	50,000
Level 2
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	322,701	2,000
Marketable securities, aggregate fair value	3,093,441	1,832,271
Total financial assets	3,416,142	1,834,271
Level 2 | U.S. Treasury securities
Fair Value Measurements, Financial Assets
Marketable securities, aggregate fair value	0	0
Level 2 | Corporate debt securities and commercial paper
Fair Value Measurements, Financial Assets
Marketable securities, aggregate fair value	3,093,441	1,832,271
Level 3
Fair Value Measurements, Financial Assets
Total financial assets	0	0
Carrying Value | Money market funds
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	1,867,034	656,749
Carrying Value | Commercial paper
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	322,701	2,000
Aggregate Fair Value | Money market funds
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	1,867,034	656,749
Aggregate Fair Value | Commercial paper
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	322,701	2,000
Aggregate Fair Value | Level 1 | Money market funds
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	1,867,034	656,749
Aggregate Fair Value | Level 2 | Commercial paper
Fair Value Measurements, Financial Assets
Cash and cash equivalents:	$ 322,701	$ 2,000

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	May 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest earned on marketable securities	$ 3,900,000	$ 8,800,000
Note receivable	9,300,000		$ 9,300,000
Impairment of long-lived assets	$ 0	$ 0
Senior Notes 3.525 Percent Due 2029
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate (as a percent)	3.625%
Senior Notes 3.525 Percent Due 2029 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of the notes	$ 510,500,000
Senior Notes 3.875 Percent Due 2031
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate (as a percent)	3.875%
Senior Notes 3.875 Percent Due 2031 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of the notes	$ 512,800,000
Convertible senior notes, 0.25%, due 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate (as a percent)				0.25%
Convertible senior notes, 0.25%, due 2023 | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of the notes	$ 1,300,000,000		$ 1,700,000,000

Fair Value Measurements - Contr

Fair Value Measurements - Contractual Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Less than one year, amortized cost	$ 1,322,778	$ 1,126,091
One to three years, amortized cost	2,048,280	971,413
Total amortized cost	3,371,058	2,097,504
Less than one year, aggregate fair value	1,325,489	1,128,927
One to three years, aggregate fair value	2,049,795	976,979
Total aggregate fair value	$ 3,375,284	$ 2,105,906

Property and Equipment - Proper

Property and Equipment - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property and Equipment
Total property and equipment	$ 342,473	$ 313,323
Less: accumulated depreciation and amortization	(146,588)	(130,084)
Total property and equipment, net	195,885	183,239
Capitalized internal-use software development costs
Property and Equipment
Total property and equipment	154,117	142,489
Data center equipment
Property and Equipment
Total property and equipment	49,627	43,477
Leasehold improvements
Property and Equipment
Total property and equipment	70,663	69,756
Office equipment
Property and Equipment
Total property and equipment	45,040	35,346
Furniture and fixtures
Property and Equipment
Total property and equipment	12,808	12,312
Software
Property and Equipment
Total property and equipment	$ 10,218	$ 9,943

Property and Equipment - Narrat

Property and Equipment - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Abstract]
Depreciation and amortization	$ 14,400	$ 11,900
Capitalized internal use software development costs	15,100	12,000
Stock-based compensation capitalized in software development costs	4,650	3,418
Capitalized Computer Software, Amortization	$ 4,500	$ 4,600

Right-of-Use Asset and Lease _3

Right-of-Use Asset and Lease Liabilities - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)property
Lessee, Lease, Description [Line Items]
Number of leased properties | property	24
Renewal option	5 years
Operating lease, not yet commenced, liability	$ 11
Finance lease not yet commenced, liability	$ 0
Minimum
Lessee, Lease, Description [Line Items]
Term of lease	1 month 6 days
Operating lease, not yet commenced, term of contract	6 years 2 months 12 days

Right-of-Use Asset and Lease _4

Right-of-Use Asset and Lease Liabilities - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Operating lease cost	$ 14,873	$ 10,424
Finance lease cost:
Amortization of assets	2,680	1,904
Interest on lease liabilities	263	198
Short-term lease cost	1,692	1,412
Variable lease cost	2,900	1,296
Total net lease cost	$ 22,408	$ 15,234

Right-of-Use Asset and Lease _5

Right-of-Use Asset and Lease Liabilities - Balance Sheet Classification of Lease Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
ASSETS
Operating lease assets	$ 241,328	$ 258,610
Finance lease assets	28,357	25,771
Total leased assets	269,685	284,381
Current liabilities:
Operating	46,239	48,338
Finance	9,389	9,062
Noncurrent liabilities
Operating	214,456	229,905
Finance	19,933	17,856
Total lease liabilities	290,017	305,161
Operating lease accumulated amortization	65,200	57,100
Finance lease accumulated depreciation	$ 17,700	$ 15,000

Right-of-Use Asset and Lease _6

Right-of-Use Asset and Lease Liabilities - Supplemental Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 14,691	$ 9,953
Operating cash flows from finance leases (interest)	263	198
Financing cash flows from finance leases	$ 2,748	$ 1,881
Weighted average remaining lease term (in years):
Operating leases	5 years 10 months 24 days		5 years 9 months 18 days
Finance leases	3 years 4 months 24 days		2 years 10 months 24 days
Weighted average discount rate:
Operating leases (as a percent)	4.80%		5.70%
Finance leases (as a percent)	3.70%		5.30%

Right-of-Use Asset and Lease _7

Right-of-Use Asset and Lease Liabilities - Lease Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Maturity Of Operating Lease Liabilities
2021 (remaining nine months)	$ 42,698
2022	57,060
2023	48,937
2024	44,373
2025	32,167
Thereafter	75,304
Total lease payments	300,539
Less: imputed interest	(39,844)
Total lease obligations	260,695
Less: current obligations	(46,239)	$ (48,338)
Long-term lease obligations	214,456	229,905
Maturity Of Finance Lease Liabilities
2021 (remaining nine months)	7,911
2022	8,987
2023	8,240
2024	4,999
2025	547
Thereafter	518
Total lease payments	31,202
Less: imputed interest	(1,880)
Total lease obligations	29,322
Less: current obligations	(9,389)	(9,062)
Long-term lease obligations	$ 19,933	$ 17,856

Business Combinations - Conside

Business Combinations - Consideration (Details) - ValueFirst - USD ($) $ in Millions	Mar. 12, 2021	Mar. 31, 2021
Acquisition
Payments to acquire businesses, gross	$ 70.2
Acquisition related costs		$ 1.3

Business Combinations - Purchas

Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 12, 2021	Dec. 31, 2020
Acquisition
Goodwill	$ 4,635,177		$ 4,595,394
ValueFirst
Acquisition
Net liabilities		$ 9,756
Intangible assets		30,300
Deferred tax liability		(6,179)
Goodwill		36,356
Total purchase price		$ 70,233

Business Combinations - Identif

Business Combinations - Identifiable Finite-lived Intangible Assets (Details) - ValueFirst $ in Thousands	Mar. 12, 2021USD ($)
Acquisitions
Intangible assets	$ 30,300
Developed technology
Acquisitions
Intangible assets	$ 6,700
Intangible assets, estimated life	7 years
Customer relationships
Acquisitions
Intangible assets	$ 11,200
Intangible assets, estimated life	7 years
Trademark and tradename
Acquisitions
Intangible assets	$ 4,700
Intangible assets, estimated life	5 years
Supplier relationships
Acquisitions
Intangible assets	$ 7,700
Intangible assets, estimated life	5 years

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Goodwill Rollforward (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Goodwill
Balance (beginning of period)	$ 4,595,394
Goodwill additions and adjustments	39,783
Balance (end of period)	$ 4,635,177

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Amortizable intangible assets:
Gross	$ 1,177,717	$ 1,147,219
Accumulated Amortization	(231,048)	(185,861)
Net	946,669	961,358
Intangible assets, gross	1,182,932	1,152,434
Total	951,884	966,573
Trademark and tradename
Amortizable intangible assets:
Non-amortizable intangible assets:	4,920	4,920
Trademarks and other
Amortizable intangible assets:
Non-amortizable intangible assets:	295	295
Developed technology
Amortizable intangible assets:
Gross	731,311	724,599
Accumulated Amortization	(139,293)	(113,282)
Net	592,018	611,317
Customer relationships
Amortizable intangible assets:
Gross	390,564	379,344
Accumulated Amortization	(74,466)	(59,574)
Net	316,098	319,770
Supplier relationships
Amortizable intangible assets:
Gross	12,071	4,356
Accumulated Amortization	(3,461)	(3,044)
Net	8,610	1,312
Trade names
Amortizable intangible assets:
Gross	30,268	25,560
Accumulated Amortization	(9,252)	(7,921)
Net	21,016	17,639
Order backlog
Amortizable intangible assets:
Gross	10,000	10,000
Accumulated Amortization	(4,167)	(1,667)
Net	5,833	8,333
Patent
Amortizable intangible assets:
Gross	3,503	3,360
Accumulated Amortization	(409)	(373)
Net	$ 3,094	$ 2,987

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 45.2	$ 20.3

Goodwill and Intangible Asset_5

Goodwill and Intangible Assets - Total Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Intangible Assets
2021 (remaining nine months)	$ 136,983
2022	172,264
2023	168,954
2024	163,380
2025	161,067
Thereafter	144,021
Net	$ 946,669	$ 961,358

Accrued Expenses and Other Li_3

Accrued Expenses and Other Liabilities - Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Accrued payroll and related	$ 55,713	$ 54,683
Accrued bonus and commission	18,582	25,341
Accrued cost of revenue	88,882	80,620
Sales and other taxes payable	51,069	48,390
ESPP contributions	16,202	6,272
Finance lease liability, current	9,389	9,062
Accrued other expense	53,821	28,527
Total accrued expenses and other current liabilities	$ 293,658	$ 252,895

Accrued Expenses and Other Li_4

Accrued Expenses and Other Liabilities - Long-term Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accrued Liabilities and Other Liabilities [Abstract]
Deferred tax liability	$ 19,031	$ 13,684
Acquisition holdback	8,751	8,800
Accrued other expenses	14,842	14,149
Total other long-term liabilities	$ 42,624	$ 36,633

Notes Payable - Summary of Long

Notes Payable - Summary of Long-Term Debt (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	May 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 1,218,048,000	$ 302,068,000
Senior Notes 3.525 Percent Due 2029
Debt Instrument [Line Items]
Principal	500,000,000	0
Unamortized discount	(6,209,000)	0
Unamortized issuance costs	(1,213,000)	0
Long-term debt	492,578,000	0
Senior Notes 3.875 Percent Due 2031
Debt Instrument [Line Items]
Principal	500,000,000	0
Unamortized discount	(6,219,000)	0
Unamortized issuance costs	(1,216,000)	0
Long-term debt	492,565,000	0
Convertible senior notes, 0.25%, due 2023
Debt Instrument [Line Items]
Principal	261,570,000	343,702,000	$ 550,000,000
Unamortized discount	(26,455,000)	(38,406,000)
Unamortized issuance costs	(2,210,000)	(3,228,000)	$ (10,200,000)
Long-term debt	$ 232,905,000	$ 302,068,000

Notes Payable - Issuance (Detai

Notes Payable - Issuance (Details) - USD ($)	1 Months Ended	3 Months Ended
	May 31, 2018	Mar. 31, 2021	Dec. 31, 2020
Senior Notes
Debt Instrument [Line Items]
Principal		$ 1,000,000,000
Net proceeds from the debt offering		985,100,000
Debt issuance costs, gross		2,400,000
Senior Notes 3.525 Percent Due 2029
Debt Instrument [Line Items]
Principal		$ 500,000,000	$ 0
Interest rate (as a percent)		3.625%
Senior Notes 3.875 Percent Due 2031
Debt Instrument [Line Items]
Principal		$ 500,000,000	0
Interest rate (as a percent)		3.875%
Convertible senior notes, 0.25%, due 2023
Debt Instrument [Line Items]
Principal	$ 550,000,000	$ 261,570,000	$ 343,702,000
Interest rate (as a percent)	0.25%
Net proceeds from the debt offering	$ 537,000,000
Convertible senior notes, 0.25%, due 2023 - over-allotment
Debt Instrument [Line Items]
Principal	$ 75,000,000

Notes Payable - Terms (Details)

Notes Payable - Terms (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	May 31, 2018USD ($)$ / shares	Mar. 31, 2021USD ($)D$ / sharesshares	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)
Debt Instrument [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.001		$ 0.001
Carrying amount of equity component		$ 342,700
Effective percentage		5.70%
Debt conversion, converted instrument, amount including cash		$ 422,700
Debt instrument, liability component		80,100
Loss on extinguishment of debt		$ (7,602)	$ 0
Common Stock Class A
Debt Instrument [Line Items]
Common stock, par value (in dollars per share) | $ / shares	$ 0.001
Common Stock Class A | Common Stock
Debt Instrument [Line Items]
Equity component from partial settlement of 2023 convertible senior notes (in shares) | shares		1,158,381
Senior Notes 3.525 Percent Due 2029
Debt Instrument [Line Items]
Interest rate (as a percent)		3.625%
Unamortized issuance costs		$ (1,213)		$ 0
Senior Notes 3.525 Percent Due 2029 | Redemption Period One
Debt Instrument [Line Items]
Debt instrument, maximum redemption price as a percentage of principal 180 days after equity offer		40.00%
Debt instrument, minimum redemption price as a percentage of principal outstanding		50.00%
Senior Notes 3.525 Percent Due 2029 | Redemption Period One | Minimum
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.00%
Senior Notes 3.525 Percent Due 2029 | Redemption Period One | Maximum
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		103.625%
Senior Notes 3.525 Percent Due 2029 | Redemption Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		101.813%
Senior Notes 3.525 Percent Due 2029 | Redemption Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.906%
Senior Notes 3.525 Percent Due 2029 | Redemption Period Four
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.00%
Senior Notes 3.875 Percent Due 2031
Debt Instrument [Line Items]
Interest rate (as a percent)		3.875%
Unamortized issuance costs		$ (1,216)		0
Senior Notes 3.875 Percent Due 2031 | Redemption Period One
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		103.875%
Debt instrument, maximum redemption price as a percentage of principal 180 days after equity offer		40.00%
Debt instrument, minimum redemption price as a percentage of principal outstanding		50.00%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Two
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.00%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Three
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		101.938%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Four
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		101.292%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Five
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.646%
Senior Notes 3.875 Percent Due 2031 | Redemption Period Six
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage		100.00%
Convertible senior notes, 0.25%, due 2023
Debt Instrument [Line Items]
Threshold trading days | D		20
Consecutive trading period | D		30
Minimum sale price of stock as a percentage of the conversion price		130.00%
Number of consecutive trading days of threshold Notes trading price for conversion eligibility to follow | D		5
Trading price as a percentage of the product of common stock sale price and conversion rate		98.00%
Percentage of principal amount of the Notes		100.00%
Interest rate (as a percent)	0.25%
Carrying amount of equity component		$ 56,801		74,636	$ 119,400
Unamortized issuance costs	$ (10,200)	(2,210)		$ (3,228)
Debt settlement, amount		$ 82,100
Convertible senior notes, 0.25%, due 2023 | Common Stock Class A
Debt Instrument [Line Items]
Conversion ratio	14.104
Capped calls
Debt Instrument [Line Items]
Initial strike price (in dollars per share) | $ / shares	$ 70.90

Notes Payable - Net Carrying Am

Notes Payable - Net Carrying Amount (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net carrying amount of the equity component of the Notes
Proceeds allocated to the conversion options (debt discount)	$ 342,700
Issuance costs	(727)
Convertible senior notes, 0.25%, due 2023
Net carrying amount of the equity component of the Notes
Proceeds allocated to the conversion options (debt discount)	56,801	$ 74,636	$ 119,400
Issuance costs	(2,819)	(2,819)
Net carrying amount	$ 53,982	$ 71,817

Notes Payable - Interest Expens

Notes Payable - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest expense recognized related to the Notes
Amortization of debt discount and issuance costs	$ 3,373	$ 6,178
Senior Notes 3.525 Percent Due 2029
Interest expense recognized related to the Notes
Contractual interest expense	1,120
Amortization of debt discount	49
Total interest expense	1,169
Senior Notes 3.875 Percent Due 2031
Interest expense recognized related to the Notes
Contractual interest expense	1,197
Amortization of debt discount	37
Total interest expense	1,234
Convertible senior notes, 0.25%, due 2023
Interest expense recognized related to the Notes
Contractual interest expense	170	344
Amortization of debt discount and issuance costs	259	484
Amortization of debt discount	3,028	5,694
Total interest expense	$ 3,457	$ 6,522

Notes Payable - Capped Calls (D

Notes Payable - Capped Calls (Details) - Capped calls $ / shares in Units, $ in Millions	1 Months Ended
	May 31, 2018USD ($)$ / sharesshares
Capped calls
Initial strike price (in dollars per share)	$ 70.90
Initial cap price (in dollars per share)	$ 105.04
Number of shares covered | shares	7,757,200
Net cost to purchase the transactions | $	$ 58.5

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information - Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Allowance for doubtful accounts
Balance, beginning of period	$ 12,046	$ 6,287
Additions	3,381	4,261
Write-offs	(2,036)	(1,463)
Balance, end of period	$ 13,391	$ 9,085
Percentage of revenue	2.00%	2.00%

Supplemental Balance Sheet In_4

Supplemental Balance Sheet Information - Sales Credit Reserve (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Sales credit reserve
Percentage of revenue	3.00%	3.00%
Sales credit reserve
Sales credit reserve
Balance, beginning of period	$ 16,783	$ 6,784
Additions	15,466	8,174
Deductions against reserve	(14,998)	(5,271)
Balance, end of period	$ 17,251	$ 9,687

Revenue by Geographic Area - Re

Revenue by Geographic Area - Revenue by Geographic Area (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenue by geographic area:
Revenue	$ 589,988	$ 364,868
United States
Revenue by geographic area:
Revenue	421,531	261,813
International
Revenue by geographic area:
Revenue	$ 168,457	$ 103,055

Revenue by Geographic Area - Pe

Revenue by Geographic Area - Percentage of Revenue by Geographic Area (Details) - Revenue from Contract with Customer Benchmark - Geographic Concentration Risk	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
United States
Percentage of revenue by geographic area:
Percentage of revenue (as a percent)	71.00%	72.00%
International
Percentage of revenue by geographic area:
Percentage of revenue (as a percent)	29.00%	28.00%

Commitments and Contingencies -

Commitments and Contingencies - Other Commitments (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Feb. 28, 2021	Mar. 31, 2021	Mar. 31, 2020
Long-term Purchase Commitment [Line Items]
Term of non-cancellable agreement		3 years
Purchase commitment		$ 426,900
Payments to acquire investments		1,640,499	$ 228,025
Syniverse
Long-term Purchase Commitment [Line Items]
Payments to acquire investments	$ 750,000
Deferred costs		$ 3,300
Minimum
Long-term Purchase Commitment [Line Items]
Term of non-cancellable lease		1 year
Maximum
Long-term Purchase Commitment [Line Items]
Term of non-cancellable lease		8 years

Commitments and Contingencies_2

Commitments and Contingencies - Indemnification Agreements (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Indemnification Agreements
Loss Contingencies [Line Items]
Amount accrued	$ 0	$ 0

Commitments and Contingencies_3

Commitments and Contingencies - Other taxes (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Taxes payable, jurisdictional estimate	$ 38.8
Accrued taxes	11.5
Liability for uncertain tax positions	$ 26.6	$ 25.6

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Preferred Stock
Preferred stock, authorized (in shares)	100,000,000	100,000,000
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock (Details)	Mar. 31, 2021vote$ / sharesshares	Dec. 31, 2020vote$ / sharesshares	May 31, 2018$ / shares
Common Stock
Common stock, par value (in dollars per share) | $ / shares	$ 0.001	$ 0.001
Common Stock Class A
Common Stock
Common stock, authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, par value (in dollars per share) | $ / shares			$ 0.001
Common stock, issued (in shares)	160,588,258	153,496,222
Common stock, outstanding (in shares)	160,588,258	153,496,222
Votes per share | vote		1
Common Stock Class B
Common Stock
Common stock, authorized (in shares)	100,000,000	100,000,000
Common stock, issued (in shares)	10,343,302	10,551,302
Common stock, outstanding (in shares)	10,343,302	10,551,302
Votes per share | vote	10

Stockholders' Equity - Common_2

Stockholders' Equity - Common Stock Shares Reserved (Details) - shares	Mar. 31, 2021	Dec. 31, 2020
Stockholders' Equity
Total (in shares)	52,524,818	45,310,099
2016 Stock Option and Incentive Plan
Stockholders' Equity
Stock-based awards available for grant under 2016 Plan (in shares)	26,871,942	18,942,205
Common Stock Class A
Stockholders' Equity
Class A common stock reserved for Twilio.org (in shares)	685,163	707,265
Class A common stock reserved for the convertible senior notes (in shares)	6,411,350	7,569,731
Stock options issued and outstanding
Stockholders' Equity
Stock options issued and outstanding (in shares)	5,216,385	5,625,735
Restricted stock units issued and outstanding
Stockholders' Equity
Unvested restricted stock units and awards issued and outstanding (in shares)	6,758,222	7,523,882
Nonvested restricted stock units issued and outstanding (in shares)	6,758,222	7,523,882
Class A common stock committed under 2016 ESPP
Stockholders' Equity
Stock-based awards available for grant under 2016 Plan (in shares)	6,581,756	4,941,281

Stockholders' Equity Stockholde

Stockholders' Equity Stockholders' Equity - Public Offering (Details) - Common Stock Class A $ / shares in Units, $ in Billions	1 Months Ended
	Feb. 28, 2021USD ($)$ / sharesshares
Class of Stock [Line Items]
Shares sold in offering (in shares) | shares	4,312,500
Offering price per share (in dollars per share) | $ / shares	$ 409.60
Aggregate proceeds from stock offering | $	$ 1.8

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2021	Mar. 31, 2021
Class A common stock committed under 2016 ESPP
Stock Based Compensation
Increase in shares available for grant (in shares)	1,640,475
Weighted-average period (in years)		1 month 6 days
Performance-based stock options
Stock Based Compensation
Granted (in shares)		555,000
Options vested and exercisable - number of options outstanding (in shares)		543,437
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price		$ 31.72
RSAs
Stock Based Compensation
Granted (in shares)		24,697
Granted (in dollars per share)		$ 359.80
Outstanding RSUs, aggregate intrinsic value		$ 8.9
Class A shares in escrow subject to future vesting
Stock Based Compensation
Outstanding RSUs, aggregate intrinsic value		$ 88.1
Shares subject to future vesting conditions (in shares)		258,554
Weighted-average period (in years)		2 years 6 months
Shares subject to future vesting conditions, weighted average grant date fair value (in dollars per share)		$ 273.38
2016 Stock Option and Incentive Plan
Stock Based Compensation
Increase in shares available for grant (in shares)	8,202,376

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Details) - Employee and nonemployee stock options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Number of options outstanding
Outstanding options as of the beginning of the period (in shares)	5,070,735
Granted (in shares)	108,429
Exercised (in shares)	(459,379)
Forfeited and cancelled (in shares)	(58,400)
Outstanding options as of the end of the period (in shares)	4,661,385
Weighted- average exercise price (Per share)
Outstanding options as of the beginning of the period (in dollars per share)	$ 51.71
Granted (in dollars per share)	378.11
Exercised (in dollars per share)	25.17
Forfeited and cancelled (in dollars per share)	62.63
Outstanding options as of the end of the period (in dollars per share)	$ 61.78
Weighted- average remaining contractual term (In years)
Weighted-average remaining contractual term (in years)	6 years 8 months 1 day	6 years 10 months 6 days
Aggregate intrinsic value	$ 1,304,466		$ 1,454,222
Options vested and exercisable and options vested and expected to vest
Options vested and exercisable - number of options outstanding (in shares)	2,609,089
Options vested and exercisable - weighted-average exercise price (in dollars per share)	$ 26.89
Options vested and exercisable - weighted-average remaining contractual term	5 years 4 months 6 days
Options vested and exercisable - aggregate intrinsic value	$ 818,926

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock Options - Additional Information (Details) - Employee and nonemployee stock options - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Stock Based Compensation
Aggregate intrinsic value of stock options exercised	$ 165,559	$ 68,359
Total estimated grant date fair value of options vested	$ 31,979	$ 23,335
Weighted-average grant date fair value per share of options granted (in dollars per share)	$ 205.36	$ 60.47

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units Activity (Details) - Restricted stock units issued and outstanding - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Number of awards outstanding
Nonvested RSUs at the beginning of the period (in shares)	7,523,882
Granted (in shares)	314,291
Vested (in shares)	(919,022)
Forfeited and canceled (in shares)	(160,929)
Nonvested RSUs at the end of the period (in shares)	6,758,222
Weighted- average grant date fair value (Per share)
Nonvested RSUs at the beginning of the period (in dollars per share)	$ 131.76
Granted (in dollars per share)	389.26
Vested (in dollars per share)	84.12
Forfeited and canceled (in dollars per share)	124.66
Nonvested RSUs at the end of the period (in dollars per share)	$ 150.39
Aggregate intrinsic value (In thousands)
Aggregate intrinsic value	$ 2,302,932	$ 2,542,858

Stock-Based Compensation - Re_2

Stock-Based Compensation - Restricted Stock Units - Unrecognized Compensation Cost (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Stock Based Compensation
Unvested stock options	$ 225,119
Total	$ 1,209,635
Equity Option
Stock Based Compensation
Weighted-average period (in years)	2 years 4 months 24 days
Restricted stock units issued and outstanding
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 923,508
Weighted-average period (in years)	2 years 10 months 24 days
Class A shares in escrow subject to future vesting
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 58,889
Weighted-average period (in years)	2 years 6 months
Class A common stock committed under 2016 ESPP
Stock Based Compensation
Unrecognized compensation cost, other than options	$ 2,119
Weighted-average period (in years)	1 month 6 days

Stock-Based Compensation - Valu

Stock-Based Compensation - Valuation Assumptions (Details) - Employee stock options - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Valuation Assumptions
Expected term (in years)	6 years 29 days	6 years 29 days
Expected volatility, low end of range (as a percent)	58.30%
Expected volatility, high end of range (as a percent)	58.40%	51.90%
Risk-free interest rate, low end of range (as a percent)	0.80%	1.30%
Risk-free interest rate, high end of range (as a percent)	1.00%	1.40%
Dividend rate (as a percent)	0.00%	0.00%
Minimum
Valuation Assumptions
Fair value of common stock (in dollars per share)	$ 377.6	$ 117.9
Maximum
Valuation Assumptions
Fair value of common stock (in dollars per share)	$ 409.2	$ 126.7

Stock-Based Compensation - St_3

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Stock-Based Compensation Expense
Stock-based compensation expense	$ 137,155	$ 69,025
Cost of revenue
Stock-Based Compensation Expense
Stock-based compensation expense	2,717	1,837
Research and development
Stock-Based Compensation Expense
Stock-based compensation expense	56,959	33,209
Sales and marketing
Stock-Based Compensation Expense
Stock-based compensation expense	41,636	19,943
General and administrative
Stock-Based Compensation Expense
Stock-based compensation expense	$ 35,843	$ 14,036

Net Loss per Share Attributab_3

Net Loss per Share Attributable to Common Stockholders - General Information (Details) - vote	Mar. 31, 2021	Dec. 31, 2020
Common Stock Class A
Net Loss Per Share Attributable to Common Stockholders
Votes per share		1
Common Stock Class B
Net Loss Per Share Attributable to Common Stockholders
Votes per share	10

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net Loss Per Share Attributable to Common Stockholders
Net loss attributable to common stockholders (in thousands)	$ (206,542)	$ (94,791)
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted (in shares)	167,160,458	139,231,594
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.24)	$ (0.68)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.24)	$ (0.68)

Net Loss Per Share Attributab_5

Net Loss Per Share Attributable to Common Stockholders - Anti-Dilutive Securities (Details) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Anti-dilutive securities
Antidilutive securities (in shares)	16,815,207	19,266,388
Conversion price (in dollars per share)	$ 70.90
Stock options issued and outstanding
Anti-dilutive securities
Antidilutive securities (in shares)	5,216,385	7,492,970
Restricted stock units issued and outstanding
Anti-dilutive securities
Antidilutive securities (in shares)	6,758,222	8,039,823
Class A common stock reserved for Twilio.org
Anti-dilutive securities
Antidilutive securities (in shares)	685,163	773,571
Class A common stock committed under 2016 ESPP
Anti-dilutive securities
Antidilutive securities (in shares)	101,030	212,028
Convertible senior notes
Anti-dilutive securities
Antidilutive securities (in shares)	3,689,177	2,747,996
Class A common stock in escrow
Anti-dilutive securities
Antidilutive securities (in shares)	75,612	0
Class A common stock in escrow and restricted stock awards subject to future vesting
Anti-dilutive securities
Antidilutive securities (in shares)	289,618	0

Income Taxes Income Taxes - Add

Income Taxes Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Tax expense (benefit)	$ 890	$ 977