Slack (WORK) 10-Q 8 Sep 20 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jul. 31, 2020	Aug. 17, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jul. 31, 2020
Document Transition Report	false
Entity File Number	001-38926
Entity Registrant Name	Slack Technologies, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-4400325
Entity Address, Address Line One	500 Howard Street
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	630-7943
Title of 12(b) Security	Class A Common Stock, $0.0001 par value per share
Trading Symbol	WORK
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Central Index Key	0001764925
Current Fiscal Year End Date	--01-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false
Class A Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		483,125,892
Class B Common Stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		87,398,710

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,316,395	$ 498,999
Marketable securities	216,957	269,593
Accounts receivable, net	111,950	145,844
Prepaid expenses and other current assets	58,340	55,967
Total current assets	1,703,642	970,403
Restricted cash	38,490	38,490
Strategic investments	42,826	28,814
Property and equipment, net	98,729	102,340
Operating lease right-of-use assets	185,911	197,830
Intangible assets, net	18,019	13,530
Goodwill	76,204	48,598
Other assets	37,306	41,701
Total assets	2,201,127	1,441,706
Current liabilities:
Accounts payable	12,778	16,893
Accrued compensation and benefits	68,154	65,196
Accrued expenses and other current liabilities	23,823	32,123
Operating lease liability	30,707	30,465
Deferred revenue	382,675	375,263
Total current liabilities	518,137	519,940
Convertible senior notes, net	630,326	0
Operating lease liability, noncurrent	185,166	196,378
Deferred revenue, noncurrent	732	1,451
Other liabilities	67	38
Total liabilities	1,334,428	717,807
Commitments and contingencies (Note 8)
Stockholders’ equity:
Common stock	57	56
Additional paid-in-capital	2,235,200	1,945,446
Accumulated other comprehensive income (loss)	929	(71)
Accumulated deficit	(1,386,680)	(1,236,621)
Total Slack Technologies, Inc. stockholders’ equity	849,506	708,810
Noncontrolling interest	17,193	15,089
Total stockholders’ equity	866,699	723,899
Total liabilities and stockholders’ equity	$ 2,201,127	$ 1,441,706

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Income Statement [Abstract]
Revenue	$ 215,864	$ 144,973	$ 417,514	$ 279,794
Cost of revenue	28,387	31,106	53,989	49,680
Gross profit	187,477	113,867	363,525	230,114
Operating expenses:
Research and development	94,201	217,769	185,426	268,872
Sales and marketing	109,122	136,392	219,442	203,230
General and administrative	52,788	123,356	103,442	160,100
Total operating expenses	256,111	477,517	508,310	632,202
Loss from operations	(68,634)	(363,650)	(144,785)	(402,088)
Interest expense	(11,552)	(208)	(14,394)	(321)
Interest income and other income, net	6,952	3,319	11,660	10,509
Loss before income taxes	(73,234)	(360,539)	(147,519)	(391,900)
Provision (benefit) for income taxes	(81)	(923)	61	(403)
Net loss	(73,153)	(359,616)	(147,580)	(391,497)
Net income (loss) attributable to noncontrolling interest	1,695	(54)	2,479	1,397
Net loss attributable to Slack	$ (74,848)	$ (359,562)	$ (150,059)	$ (392,894)
Basic and diluted net loss per share:
Net loss per share attributable to Slack common stockholders, basic and diluted (in dollars per share)	$ (0.13)	$ (0.98)	$ (0.27)	$ (1.58)
Weighted-average shares used in computing net loss per share attributable to Slack common stockholders, basic and diluted (in shares)	564,351	368,533	560,921	249,222

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (73,153)	$ (359,616)	$ (147,580)	$ (391,497)
Other comprehensive income (loss), net of tax:
Change in unrealized gain or loss on marketable securities	75	(41)	1,000	379
Other comprehensive income (loss), net of tax	75	(41)	1,000	379
Comprehensive loss	(73,078)	(359,657)	(146,580)	(391,118)
Comprehensive income (loss) attributable to noncontrolling interest	1,695	(54)	2,479	1,397
Comprehensive loss attributable to Slack	$ (74,773)	$ (359,603)	$ (149,059)	$ (392,515)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-In-Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Noncontrolling Interest	Restricted stockCommon Stock	Restricted stock unitsCommon Stock
Beginning of period (in shares) at Jan. 31, 2019		373,372	127,573
Beginning of period at Jan. 31, 2019	$ 841,606	$ 1,392,101	$ 13	$ 105,633	$ (498)	$ (665,563)	$ 9,920
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			2,694
Exercise of stock options	2,907			2,907
Vesting of early exercised stock options	88			88
Issuance of restricted stock awards (in shares)								505
Other comprehensive income	420				420
Stock-based compensation	3,639			3,639
Net income (loss)	(31,881)					(33,332)	1,451
End of period (in shares) at Apr. 30, 2019		373,372	130,772
End of period at Apr. 30, 2019	816,779	$ 1,392,101	$ 13	112,267	(78)	(698,895)	11,371
Beginning of period (in shares) at Jan. 31, 2019		373,372	127,573
Beginning of period at Jan. 31, 2019	841,606	$ 1,392,101	$ 13	105,633	(498)	(665,563)	9,920
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of early exercised stock options	157
Other comprehensive income	379
Net income (loss)	(391,497)
End of period (in shares) at Jul. 31, 2019			542,566
End of period at Jul. 31, 2019	749,783		$ 54	1,796,988	(119)	(1,058,457)	11,317
Beginning of period (in shares) at Apr. 30, 2019		373,372	130,772
Beginning of period at Apr. 30, 2019	816,779	$ 1,392,101	$ 13	112,267	(78)	(698,895)	11,371
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			8,046
Exercise of stock options	6,805		$ 1	6,804
Vesting of early exercised stock options	69			69
Cancellation of restricted stock options (in shares)			(10)
Repurchase of early exercised stock options (in shares)			(2)
Conversion of convertible preferred stock to common stock in connection with direct listing (in shares)		(373,372)	(373,372)
Conversion of convertible preferred stock to common stock in connection with direct listing		$ (1,392,101)	$ (37)	(1,392,064)
Issuance of common stock upon settlement of restricted stock units (in shares)			30,388
Issuance of common stock upon settlement of restricted stock units (RSUs)			$ (3)	(3)
Other comprehensive income	(41)				(41)
Stock-based compensation	285,787			285,787
Net income (loss)	(359,616)					(359,562)	(54)
End of period (in shares) at Jul. 31, 2019			542,566
End of period at Jul. 31, 2019	749,783		$ 54	1,796,988	(119)	(1,058,457)	11,317
Beginning of period (in shares) at Jan. 31, 2020			555,360
Beginning of period at Jan. 31, 2020	723,899		$ 56	1,945,446	(71)	(1,236,621)	15,089
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			1,062
Exercise of stock options	1,932			1,932
Vesting of early exercised stock options	2			2
Issuance of common stock upon settlement of restricted stock units (in shares)									4,724
Equity component of convertible senior notes, net of issuance costs	223,622			223,622
Purchases of capped calls related to convertible senior notes	(105,570)			(105,570)
Other comprehensive income	925				925
Issuance of common stock for employee share purchase plan (in shares)			820
Issuance of common stock for employee share purchase plan	16,610			16,610
Stock-based compensation	53,711			53,711
Net income (loss)	(74,427)					(75,211)	784
End of period (in shares) at Apr. 30, 2020			561,966
End of period at Apr. 30, 2020	840,704		$ 56	2,135,753	854	(1,311,832)	15,873
Beginning of period (in shares) at Jan. 31, 2020			555,360
Beginning of period at Jan. 31, 2020	$ 723,899		$ 56	1,945,446	(71)	(1,236,621)	15,089
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)	1,828
Vesting of early exercised stock options	$ 974
Other comprehensive income	1,000
Net income (loss)	(147,580)
End of period (in shares) at Jul. 31, 2020			569,408
End of period at Jul. 31, 2020	866,699		$ 57	2,235,200	929	(1,386,680)	17,193
Beginning of period (in shares) at Apr. 30, 2020			561,966
Beginning of period at Apr. 30, 2020	840,704		$ 56	2,135,753	854	(1,311,832)	15,873
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)			766
Exercise of stock options	1,693			1,693
Vesting of early exercised stock options	972			972
Issuance of common stock upon settlement of restricted stock units (in shares)									5,016
Issuance of common stock upon settlement of restricted stock units (RSUs)				(1)					$ (1)
Other comprehensive income	75				75
Distributions to noncontrolling interest holders	(375)						(375)
Shares issued during period (in shares)			1,660
Shares issued related to a business combination	39,495			39,495
Stock-based compensation	57,288			57,288
Net income (loss)	(73,153)					(74,848)	1,695
End of period (in shares) at Jul. 31, 2020			569,408
End of period at Jul. 31, 2020	$ 866,699		$ 57	$ 2,235,200	$ 929	$ (1,386,680)	$ 17,193

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019
Cash flows from operating activities:
Net loss	$ (147,580)	$ (391,497)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	13,641	12,657
Stock-based compensation	110,999	289,426
Amortization of debt discount and issuance costs	12,619	0
Noncash operating lease expense	17,343	0
Amortization of deferred contract acquisition costs	6,898	3,290
Net amortization of bond premium (discount) on debt securities available for sale	381	(1,736)
Change in fair value of strategic investments	(5,820)	(2,884)
Other non-cash charges	(218)	(359)
Changes in operating assets and liabilities:
Accounts receivable	33,548	15,258
Prepaid expenses and other assets	(4,539)	(10,161)
Accounts payable	(4,038)	(1,436)
Operating lease liabilities	(16,371)	0
Accrued compensation and benefits	2,955	19,758
Deferred revenue	5,703	44,650
Other current and long-term liabilities	(2,321)	9,229
Net cash provided by (used in) operating activities	23,200	(13,805)
Cash flows from investing activities:
Purchases of marketable securities	(100,302)	(59,553)
Maturities of marketable securities	147,913	268,951
Sales of marketable securities	5,650	166,074
Net cash acquired from a business combination	6,571	0
Purchases of property and equipment	(8,743)	(28,269)
Purchase of strategic investments	(9,025)	(5,470)
Proceeds from liquidation of strategic investments	789	2,858
Net cash provided by investing activities	42,853	344,591
Cash flows from financing activities:
Proceeds from issuance of convertible senior notes, net of issuance costs	841,329	0
Purchases of capped calls related to convertible senior notes	(105,570)	0
Proceeds from exercise of stock options	4,599	10,275
Payments of contingent consideration for acquisitions	(5,250)	(5,000)
Issuance of common stock for employee stock purchase plan	16,610	0
Distributions to noncontrolling interest holders	(375)	0
Other financing activities	0	(556)
Net cash provided by financing activities	751,343	4,719
Net increase in cash, cash equivalents and restricted cash	817,396	335,505
Cash, cash equivalents and restricted cash at beginning of period	537,489	201,260
Cash, cash equivalents and restricted cash at end of period	1,354,885	536,765
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,894	455
Non-cash investing and financing activities:
Increase (decrease) in purchases of property and equipment included in liabilities	(1,349)	1,476
Fair value of common stock issued as consideration for a business combination	39,495	0
Vesting of early exercised stock options	974	157
Unrealized short-term gain on marketable securities	$ 991	$ 505

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	6 Months Ended
	Jul. 31, 2020
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Business Slack Technologies, Inc. (the “Company” or “Slack”) operates a business technology software platform that brings together people, applications, and data and sells its offering under a software-as-a-service model. The Company was incorporated in Delaware in 2009 as Tiny Speck, Inc. In 2014, the Company changed its name to Slack Technologies, Inc. and publicly launched its current offering. The Company is headquartered in San Francisco, California. Fiscal Year The Company’s fiscal year ends on January 31. References to fiscal year 2021, for example, refer to the fiscal year ended January 31, 2021. Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”), regarding interim financial reporting. The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned and majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The condensed consolidated financial statements include 100% of the accounts of wholly owned and majority-owned subsidiaries and the ownership interest of minority investors is recorded as noncontrolling interest. The unaudited condensed consolidated balance sheet as of January 31, 2020 included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by U.S. GAAP on an annual reporting basis. In management's opinion, the unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the balance sheets, statements of comprehensive loss, statements of stockholders’ equity, and statements of cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full fiscal year or any future period. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 12, 2020. Convertible Senior Notes In April 2020, the Company issued $862.5 million aggregate principal amount of 0.50% convertible senior notes due April 15, 2025 in a private offering, including the initial purchasers’ exercise in full of their option to purchase additional notes (the “Notes”). See Note 7 for additional details. Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. These estimates are based on information available as of the date of the condensed consolidated financial statements. On a regular basis, management evaluates these estimates and assumptions; however, actual results could materially differ from these estimates due to risks and uncertainties, including uncertainty in the current economic environment related to the outbreak of the novel coronavirus pandemic (“COVID-19”). The Company’s most significant estimates and judgments involve revenue recognition, stock-based compensation including the estimation of fair value of common stock, valuation of strategic investments, valuation of acquired goodwill and intangibles from acquisitions, period of benefit for deferred contract acquisition costs, fair value of the liability and equity components of the Notes, and uncertain tax positions. Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk primarily consist of cash and cash equivalents, restricted cash, marketable securities, and accounts receivable. For cash, cash equivalents, restricted cash, and marketable securities, the Company is exposed to credit risk in the event of default by the financial institutions to the extent of the amounts recorded on the accompanying condensed consolidated balance sheets that are in excess of federal insurance limits. For accounts receivable, the Company is exposed to credit risk in the event of nonpayment by customers to the extent of the amounts recorded on the accompanying condensed consolidated balance sheets. The Company sells its services to a wide variety of customers. If the financial condition or results of operations of any significant customers deteriorates 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. No customer accounted for 10% or greater of total accounts receivable as of July 31, 2020 and January 31, 2020. There were no customers representing 10% or greater of revenue for the three and six months ended July 31, 2020 and 2019. Summary of Significant Accounting Policies The Company’s significant accounting policies are discussed in “Index to Consolidated Financial Statements–Note 1. Description of Business and Summary of Significant Accounting Policies” in the Notes to Consolidated Financial Statements in its Annual Report on Form 10-K filed with the SEC on March 12, 2020. There have been no significant changes to these policies during the six months ended July 31, 2020, except for the accounting policy for the Notes issued in April 2020. Convertible Senior Notes The Notes are accounted for in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Subtopic 470-20, Debt with Conversion and Other Options . Pursuant to ASC Subtopic 470-20, issuers of certain convertible debt instruments, such as the Notes, that have a net settlement feature and may be settled wholly or partially in cash upon conversion are required to separately account for the liability (debt) and equity (conversion option) components of the instrument. The carrying amount of the liability component of the instrument is computed by estimating the fair value of a similar liability without the conversion option using a market-based approach. The amount of the equity component is then calculated by deducting the fair value of the liability component from the principal amount of the instrument. The difference between the principal amount and the liability component represents a debt discount that is amortized to interest expense over the respective term of the Notes using the effective interest rate method. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the issuance costs related to the Notes, the allocation of issuance costs incurred between the liability and equity components was based on their relative values. Recently Adopted Accounting Standards In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses (Topic 326) Measurement of Credit Losses on Financial Instruments , which requires an entity to utilize a new impairment model known as the current expected credit loss (“CECL”) model to estimate its “expected credit loss” and record an allowance that, when deducted from the amortized cost basis of the financial asset, presents the net amount expected to be collected on the financial asset. The CECL model is expected to result in more timely recognition of credit losses. This guidance also requires new disclosures for financial assets measured at amortized cost, loans and available-for-sale debt securities. The Company adopted Topic 326 as of February 1, 2020. The adoption of this new standard did not have a material impact on the accompanying condensed consolidated financial statements as credit losses are not expected to be significant based on historical collection trends, the financial condition of payment partners, and external market factors. The Company will continue to actively monitor the impact of the COVID-19 on expected credit losses. In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which aligns the accounting for implementation costs incurred in a hosting arrangement that is a service contract with the accounting for implementation costs incurred to develop or obtain internal-use software under ASC 350-40, in order to determine which costs to capitalize and recognize as an asset and which costs to expense. The Company adopted ASU No. 2018-15 as of February 1, 2020 using a prospective transition approach. The adoption of this new standard did not have a material impact on the accompanying condensed consolidated financial statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes which simplifies the accounting for income taxes by removing certain exceptions to the general principles of income taxes and reducing the cost and complexity in accounting for income taxes. The Company early adopted ASU No. 2019-12 as of February 1, 2020 using the prospective transition approach. The adoption of this new standard did not have a material impact on the accompanying condensed consolidated financial statements. Recently Issued Accounting Standards Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. ASU No. 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. ASU No. 2020-06 is effective for public companies for annual periods beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted for annual periods beginning after December 15, 2020, and interim periods within those fiscal years. The Company is currently evaluating the impact of this standard on its condensed consolidated financial statements and related disclosures.

Revenue and Contract Costs

Revenue and Contract Costs	6 Months Ended
	Jul. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue and Contract Costs	Revenue and Contract Costs Contract Balances Contract liabilities consist of deferred revenue. The changes in deferred revenue were as follows (in thousands): Three Months Ended July 31, 2020 Six Months Ended July 31, 2020 Balance, beginning of period $ 381,073 $ 376,714 Billings 217,208 423,217 Deferred revenue assumed in the Rimeto acquisition 990 990 Revenue (215,864) (417,514) Balance, end of period $ 383,407 $ 383,407 The majority of revenue recognized in the three months ended July 31, 2020 was from the deferred revenue balance as of April 30, 2020. The majority of revenue recognized in the six months ended July 31, 2020 was from the deferred revenue balance as of January 31, 2020. Remaining Performance Obligations The Company applies the practical expedient in ASC 606-10-50-14 and does not disclose information about remaining performance obligations that have original expected durations of one year or less, which applies primarily to its monthly and annual subscription contracts. As of July 31, 2020, the remaining performance obligations that were unsatisfied or partially unsatisfied at the end of the reporting period were $388.5 million, of which 57% is expected to be recognized in the twelve months following July 31, 2020, with the balance to be recognized as revenue thereafter. Disaggregation of Revenue The following table shows the Company’s revenue by geographic areas, as determined based on the billing address of its customers (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 United States $ 134,214 $ 90,734 $ 259,601 $ 175,063 International 81,650 54,239 157,913 104,731 Total $ 215,864 $ 144,973 $ 417,514 $ 279,794 No individual foreign country contributed in excess of 10% of revenue for the three months or six months ended July 31, 2020 and 2019. Deferred Contract Acquisition Costs, Net The Company deferred incremental costs of obtaining a contract of $5.4 million and $6.0 million for the three months ended July 31, 2020 and 2019, respectively, and $18.0 million and $10.8 million for the six months ended July 31, 2020 and 2019, respectively. Deferred contract acquisition costs, net included in prepaid expenses and other current assets were $15.6 million and $11.2 million as of July 31, 2020 and January 31, 2020, respectively. Deferred contract acquisition costs, net included in other assets were $28.1 million and $21.4 million as of July 31, 2020 and January 31, 2020, respectively. Amortized deferred contract acquisition costs were $3.8 million and $1.8 million for the three months ended July 31, 2020

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jul. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company’s money market funds and sweep account are classified within Level 1 of the fair value hierarchy because they are valued using quoted prices in active markets. The Company’s commercial paper, U.S. agency and government securities, international government securities, certificates of deposit, and corporate bonds are classified within Level 2 of the fair value hierarchy because they have been valued using inputs other than quoted prices in active markets that are observable directly or indirectly. The Company’s strategic investments in privately held companies are classified within Level 3 of the fair value hierarchy because they have been valued using unobservable inputs for which the Company has been required to develop its own assumptions. Realized and unrealized gains and losses relating to the strategic investments are recorded in other income (expense), net in the accompanying condensed consolidated statements of operations. The following tables provide the financial instruments measured at fair value on a recurring basis, within the fair value hierarchy (in thousands): As of July 31, 2020 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 757,213 $ — $ — $ 757,213 Certificates of deposit — 145,318 — 145,318 Total cash equivalents $ 757,213 $ 145,318 $ — $ 902,531 Marketable securities: Certificates of deposit $ — $ 7,560 $ — $ 7,560 Commercial paper — 14,990 — 14,990 U.S. agency securities — 40,377 — 40,377 U.S. government securities — 30,263 — 30,263 International government securities — 8,104 — 8,104 Corporate bonds — 115,663 — 115,663 Total marketable securities $ — $ 216,957 $ — $ 216,957 Noncurrent assets: Strategic investments $ — $ — $ 42,826 $ 42,826 As of January 31, 2020 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 357,524 $ — $ — $ 357,524 Commercial paper — 69,882 — 69,882 Total cash equivalents $ 357,524 $ 69,882 $ — $ 427,406 Marketable securities: Commercial paper $ — $ 19,795 $ — $ 19,795 U.S. agency securities — 29,515 — 29,515 U.S. government securities — 97,172 — 97,172 International government securities — 8,115 — 8,115 Corporate bonds — 114,996 — 114,996 Total marketable securities $ — $ 269,593 $ — $ 269,593 Noncurrent assets: Strategic investments $ — $ — $ 28,814 $ 28,814 The following table presents additional information about Level 3 assets measured at fair value on a recurring basis (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Balance at beginning of period $ 34,470 $ 15,266 $ 28,814 $ 12,334 Purchases 5,007 2,370 9,025 5,470 Proceeds from liquidation (833) — (833) (3,193) Realized gains 484 — 184 2,693 Unrealized gains (losses) relating to investments still held at reporting date 3,698 (140) 5,636 192 Balance at end of period $ 42,826 $ 17,496 $ 42,826 $ 17,496 Convertible Senior Notes As of July 31, 2020, the fair value of the Notes was approximately $1.04 billion. The fair value was determined based on the quoted price for the Notes in an inactive market on the last trading day of the reporting period and is considered as Level 2 in the fair value hierarchy.

Business Combination

Business Combination	6 Months Ended
	Jul. 31, 2020
Business Combinations [Abstract]
Business Combination	Business Combination On June 29, 2020, the Company completed its acquisition of all issued and outstanding shares of Rimeto Inc. (“Rimeto”), a provider of an enterprise directory platform that enables users to stay connected with detailed employee profiles and information. The Company effected the business combination by issuing 1,659,715 shares of its Class A common stock, of which 740,837 shares are subject to a re-vesting restriction over four years from the closing of the acquisition. Post-combination stock-based compensation for the re-vesting restricted stock, net of fair value of the pre-combination service portion, which is recorded as purchase price, is $11.4 million and is being ratably recognized over the requisite service period of four years. The acquisition date fair value of the purchase price was $40.1 million, which consisted of the following (in thousands): Fair Value Cash $ 653 Fair value of Class A common stock transferred 28,060 Fair value of the pre-combination service portion of restricted stock 11,435 Total purchase price $ 40,148 The following table presents the preliminary purchase price allocation recorded in the Company’s condensed consolidated balance sheet as of July 31, 2020 (in thousands): Fair Value Cash and cash equivalents $ 7,224 Accounts receivable and other assets 732 Operating lease right-of-use assets 616 Intangible assets 7,000 Goodwill 27,606 Accounts payable and other liabilities (464) Operating lease liability (637) Deferred revenue (990) Deferred tax liability (939) Total purchase price $ 40,148 The acquisition was accounted for as a business combination and the total purchase price was allocated to the net tangible and intangible assets and liabilities based on their fair values on the acquisition date and the excess was recorded as goodwill. The values assigned to the assets acquired and liabilities assumed are based on preliminary estimates of fair value available as of the date of this Quarterly Report on Form 10-Q and may be adjusted during the measurement period of up to 12 months from the date of acquisition as further information becomes available. Any changes in the fair values of the assets acquired and liabilities assumed during the measurement period may result in adjustments to goodwill. As of July 31, 2020, the primary area that remains preliminary relates to the valuation of certain tax-related items. The goodwill was primarily attributed to the value of synergies created with the Company’s current and future offerings and the value of the assembled workforce. The Company anticipates both goodwill and intangible assets to be fully deductible for income tax purposes. The following table sets forth the components of identifiable intangible assets acquired and their estimated useful lives as of the date of acquisition (in thousands): Fair Value Useful Life Developed technology $ 4,900 3 years Customer relationships 2,100 3 years Total identifiable intangible assets $ 7,000 In connection with the acquisition, the Company agreed to grant restricted stock units (“RSUs”) to Rimeto employees who joined the Company upon the effective date of the acquisition, with a value totaling approximately $19.0 million. The amount will be ratably recognized as stock-based compensation over the requisite service period of four years. The Company incurred costs related to this acquisition of $1.5 million that were recorded in general and administrative expenses in the accompanying condensed consolidated statements of operations for the three and six months ended July 31, 2020.

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jul. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Cash, Cash Equivalents, and Marketable Securities The following tables summarize the amortized cost, unrealized gains and losses, and estimated fair value of cash, cash equivalents, and marketable securities consisting of the following (in thousands): As of July 31, 2020 Amortized Unrealized Unrealized Fair value Cash and cash equivalents: Cash $ 413,864 $ — $ — $ 413,864 Money market funds 757,213 — — 757,213 Certificates of deposit 145,318 — — 145,318 Total cash and cash equivalents 1,316,395 — — 1,316,395 Marketable securities: Certificates of deposit 7,500 60 — 7,560 Commercial paper 14,944 46 — 14,990 U.S. agency securities 40,160 217 — 40,377 U.S. government securities 30,089 174 — 30,263 International government securities 8,095 9 — 8,104 Corporate bonds 114,896 767 — 115,663 Total marketable securities 215,684 1,273 — 216,957 Total cash, cash equivalents and marketable securities $ 1,532,079 $ 1,273 $ — $ 1,533,352 As of January 31, 2020 Amortized Unrealized Unrealized Fair value Cash and cash equivalents: Cash $ 71,593 $ — $ — $ 71,593 Money market funds 357,524 — — 357,524 Commercial paper 69,891 — (9) 69,882 Total cash and cash equivalents 499,008 — (9) 498,999 Marketable securities: Commercial paper 19,799 4 (8) 19,795 U.S. agency securities 29,460 55 — 29,515 U.S. government securities 97,071 102 (1) 97,172 International government securities 8,109 6 — 8,115 Corporate bonds 114,871 139 (14) 114,996 Total marketable securities 269,310 306 (23) 269,593 Total cash, cash equivalents and marketable securities $ 768,318 $ 306 $ (32) $ 768,592 The Company periodically evaluates its investments for other-than-temporary declines in fair value. The unrealized losses on the available-for-sale securities were primarily due to unfavorable changes in interest rates subsequent to the initial purchase of these securities. Gross unrealized losses of the Company’s available-for-sale securities that have been in a continuous unrealized loss position for twelve months or longer were none and immaterial as of July 31, 2020 and January 31, 2020, respectively. The Company expects to recover the full carrying value of its available-for-sale securities in an unrealized loss position as it does not intend or anticipate a need to sell these securities prior to recovering the associated unrealized losses. The Company also expects any credit losses would be immaterial based on the high-grade credit rating for each of such available-for-sale securities. As a result, the Company does not consider any portion of the unrealized losses as of July 31, 2020 or January 31, 2020 to represent an other-than temporary impairment or credit losses. The following table classifies marketable securities by contractual maturities (in thousands): As of July 31, 2020 January 31, 2020 Due in one year $ 157,970 $ 190,344 Due in one to two years 58,987 79,249 Total $ 216,957 $ 269,593 Property and Equipment, Net The following is a summary of the Company’s property and equipment by category (in thousands): As of July 31, 2020 January 31, 2020 Leasehold improvements $ 102,562 $ 98,770 Furniture and fixtures 28,347 27,384 Capitalized internal-use software costs 4,241 4,241 Computer equipment 3,783 3,183 Construction in progress 7,792 10,345 Property and equipment, gross 146,725 143,923 Less: accumulated depreciation and amortization (47,996) (41,583) Property and equipment, net $ 98,729 $ 102,340 Depreciation and amortization expense was $5.6 million and $5.8 million for the three months ended July 31, 2020 and 2019, respectively. Depreciation and amortization expense was $11.1 million and $10.6 million for the six months ended July 31, 2020 and 2019, respectively. Goodwill As of July 31, 2020 and January 31, 2020, goodwill was $76.2 million and $48.6 million, respectively. During the six months ended July 31, 2020, the Company recorded $27.6 million of goodwill in connection with the Rimeto acquisition that was completed in June 2020. See Note 4 for further details. No goodwill impairments were recorded for any period presented in the accompanying condensed consolidated statements of operations. Intangible Assets, Net Intangible assets consist of the following (in thousands): July 31, 2020 Weighted-average Gross carrying Accumulated Net carrying Customer relationships 4.5 years $ 11,200 $ 2,713 $ 8,487 Developed technology 2.3 years 13,427 6,228 7,199 Patents 4.4 years 2,500 292 2,208 Assembled workforce 0.2 years 1,198 1,073 125 Total $ 28,325 $ 10,306 $ 18,019 January 31, 2020 Weighted-average Gross carrying Accumulated Net carrying Customer relationships 5.5 years $ 9,100 $ 2,004 $ 7,096 Developed technology 1.6 years 8,527 4,976 3,551 Patents 4.9 years 2,500 42 2,458 Assembled workforce 0.7 years 1,198 773 425 Total $ 21,325 $ 7,795 $ 13,530 Amortization expense of intangible assets was $1.4 million and $1.1 million for the three months ended July 31, 2020 and 2019, respectively. Amortization expense of intangible assets was $2.5 million and $2.1 million for the six months ended July 31, 2020 and 2019, respectively. As of July 31, 2020, expected amortization expense relating to intangible assets for each of the next five fiscal years and thereafter is as follows (in thousands): Year ending January 31, 2021 (6 months remaining) $ 3,308 2022 5,452 2023 4,133 2024 2,772 2025 1,758 Thereafter 596 Total $ 18,019

Operating Leases

Operating Leases	6 Months Ended
	Jul. 31, 2020
Leases [Abstract]
Operating Leases	Operating Leases The Company leases real estate facilities under non-cancelable operating leases with various expiration dates through fiscal year 2031. For the three months ended July 31, 2020, the Company recorded operating lease costs of $10.9 million including variable operating lease costs of $1.6 million and short-term leases of $0.8 million. For the six months ended July 31, 2020, the Company recorded operating lease costs of $21.8 million, including variable operating lease costs of $2.9 million and short- term leases of $1.5 million. The following table sets forth a summary of and other information pertaining to the Company’s operating leases (dollars in thousands): Six Months Ended July 31, 2020 Operating cash flows used for operating leases $ 16,371 Operating lease liabilities arising from obtaining ROU assets $ 637 Weighted average remaining terms 8.1 years Weighted average discount rate 5.2 % Rent expense, net of sublease income under ASC 840, was $8.7 million and $17.0 million for the three and six month ended July 31, 2019, respectively. Future minimum lease payments under non-cancelable operating leases with initial lease terms in excess of one year as of July 31, 2020 as follows (in thousands): Year ending January 31, 2021 (6 months remaining) $ 13,475 2022 38,196 2023 51,810 2024 50,421 2025 52,880 Thereafter 263,278 Gross lease payments 470,060 Less: Imputed interest (57,602) Less: Tenant improvement receivables (14,022) Less: Leases executed but not yet commenced (182,563) Present value of lease liabilities $ 215,873 As of July 31, 2020, the Company had commitments of $182.6 million for non-cancelable operating leases of real estate facilities that have not yet commenced, and therefore are not included in the ROU assets or operating lease liabilities. These operating leases will commence in fiscal year 2021 with lease terms of 9.9 years to 12.0 years.

Debt and Financing Arrangements

Debt and Financing Arrangements	6 Months Ended
	Jul. 31, 2020
Debt Disclosure [Abstract]
Debt and Financing Arrangements	Debt and Financing Arrangements Convertible Senior Notes On April 9, 2020, the Company issued $862.5 million in aggregate principal amount of the Notes in a private offering pursuant to an Indenture dated April 9, 2020 (the “Indenture”), including the initial purchasers’ exercise in full of their option to purchase an additional $112.5 million principal amount of the Notes. The total net proceeds from the debt offering, after deducting initial purchaser discounts and debt issuance costs, paid or payable were $841.3 million. The Notes are senior, unsecured obligations of the Company and will accrue interest payable semiannually in arrears on April 15 and October 15 of each year, beginning on October 15, 2020, at a rate of 0.50% per year. The Notes will mature on April 15, 2025, unless earlier converted, redeemed, or repurchased. The Notes are convertible into cash, shares of the Company’s Class A common stock or a combination of cash and shares of the Company’s Class A common stock, at the Company’s election. Holders of the Notes may convert all or any portion of their Notes at their option at any time prior to the close of business on January 14, 2025 only under the following circumstances: • During any fiscal quarter commencing after the fiscal quarter ending on July 31, 2020 (and only during such fiscal quarter), if the last reported sale price of the Company’s Class A common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; • During the five business day period after any ten consecutive trading day period (the “measurement period”) in which the “trading price” (as defined in the Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s Class A common stock and the conversion rate on each such trading day; or • Upon the occurrence of specified corporate events. On or after January 15, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date, a holder may convert all or any portion of its Notes at any time, regardless of the foregoing. The conditions allowing holders of the Notes to convert have not been met since the Company issued the Notes on April 9, 2020. The conversion rate was initially 32.2630 shares of the Company’s Class A common stock per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $31.00 per share of the Company’s Class A common stock). The conversion rate is subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, the Company will, in certain circumstances, increase the conversion rate for a holder who elects to convert its Notes in connection with such a corporate event. The Company may not redeem the Notes prior to April 20, 2023. The Company may redeem for cash all or any portion of the Notes, at its option, on a redemption date occurring on or after April 20, 2023 and on or before the 21st scheduled trading day immediately before the maturity date, if the last reported sale price of the Company’s 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), including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the Notes. If the Company undergoes a fundamental change (as defined in the Indenture), holders may require the Company to repurchase for cash all or any portion of their Notes at a fundamental change repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date. The Indenture contains customary terms and covenants, including that upon certain events of default occurring and continuing, either the Trustee or the holders of not less than 25% in aggregate principal amount of the Notes then outstanding may declare the entire principal amount of all the Notes plus accrued special interest, if any, to be immediately due and payable. The Notes are the Company’s general unsecured obligations and rank senior in right of payment to all of the Company’s indebtedness that is expressly subordinated in right of payment to the Notes; equal in right of payment with all of the Company’s liabilities that are not so subordinated; effectively junior 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 the Company’s subsidiaries. In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated using a discount rate of 6.85%, which was determined 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 $229.2 million and was determined by deducting the fair value of the liability component from the par value of the 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 over the contractual terms of the Notes. As of July 31, 2020, the net carrying amount of the liability component of the Notes was as follows (in thousands): Principal $ 862,500 Less: unamortized discount (217,282) Less: unamortized issuance costs (14,892) Net carrying amount $ 630,326 As of July 31, 2020, the net carrying amount of the equity component of the Notes was as follows (in thousands): Proceeds allocated to the conversion options (debt discount) $ 229,249 Less: issuance costs (5,627) Carrying amount of the equity component $ 223,622 The following table sets forth the interest expense recognized related to the Notes (in thousands): Three Months Ended July 31, 2020 Six Months Ended July 31, 2020 Contractual interest expense $ 1,078 $ 1,330 Amortization of debt discount 9,722 11,967 Amortization of debt issuance costs 531 652 Total interest expense related to the Senior Notes $ 11,331 $ 13,949 Capped Call Transactions In connection with the offering of the Notes, the Company entered into privately negotiated capped call transactions with certain financial institution counterparties (the “Capped Calls”). The Capped Calls each have an initial strike price of approximately $31.00 per share, subject to certain adjustments, which corresponds to the initial conversion price of the Notes. The Capped Calls have initial cap prices of $48.62 per share, subject to certain adjustments. The Capped Calls cover, subject to anti-dilution adjustments, approximately 27.8 million shares of Class A common stock. The Capped Calls are generally intended to reduce or offset the potential dilution to the Class A common stock upon any conversion of the Notes with such reduction or offset, as the case may be, subject to a cap based on the cap price. The Capped Calls expire on the earlier of (i) the last day on which any convertible securities remain outstanding and (ii) April 15, 2025, subject to earlier exercise. The Capped Calls are subject to either adjustment or termination upon the occurrence of specified extraordinary events affecting the Company, including a merger event, a tender offer, and a nationalization, insolvency or delisting involving the Company. In addition, the Capped Calls are subject to certain specified additional disruption events that may give rise to a termination of the Capped Calls, including changes in law, insolvency filings, and hedging disruptions. The Capped Calls are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost of $105.6 million incurred to purchase the capped call transactions was recorded as a reduction to additional paid-in capital in the accompanying condensed consolidated balance sheet. Revolving Credit Facility On May 30, 2019, the Company entered into a $215.0 million revolving credit and guaranty agreement with a syndicate of financial institutions. The revolving credit facility has an accordion option, which, if exercised, would allow the Company to increase the aggregate commitments by up to the greater of $200.0 million and 100% of the consolidated adjusted EBITDA of the Company and its subsidiaries, plus an unlimited amount subject to satisfaction of certain leverage ratio based compliance tests after giving effect to the exercise, in each case subject to obtaining additional lender commitments and satisfying certain conditions. Pursuant to the terms of the revolving credit facility, the Company may issue letters of credit under the revolving credit facility, which reduce the total amount available for borrowing under such facility. The revolving credit facility terminates on May 30, 2024. Interest on borrowings under the revolving credit facility accrues at a variable rate tied to the prime rate or the LIBOR, plus the applicable margin, at the Company’s election. The margin is 0.25% in the case of prime rate loans and 1.25% in the case of LIBOR loans. Interest is payable quarterly in arrears. Pursuant to the terms of the revolving credit facility, the Company is required to pay an annual commitment fee that accrues at a rate of 0.10% per annum on the unused portion of the borrowing commitments under the revolving credit facility. In addition, the Company is required to pay a fee in connection with letters of credit issued and outstanding under the revolving credit facility that accrues at a rate of 1.25% per annum on the amount to be drawn under such letters of credit outstanding. There is an additional fronting fee of 0.125% per annum multiplied by the aggregate face amount of issued and outstanding letters of credit. The revolving credit facility contains customary conditions to borrowing, events of default, and covenants, including covenants that restrict the Company’s and its subsidiaries’ ability to, among other things, incur additional indebtedness, create or incur liens, merge or consolidate with other companies, sell substantially all of the Company’s assets, liquidate or dissolve, make distributions to the Company’s equity holders or its subsidiaries’ equity interests, pay dividends, make redemptions and repurchases of stock, or engage in transactions with affiliates. In addition, the revolving credit facility contains financial covenants, including a minimum liquidity balance and a minimum revenue amount. The Company has been in compliance with all covenants under the revolving credit facility since it entered into the revolving credit and guaranty agreement on May 30, 2019. As of July 31, 2020, the Company had no amounts or letters of credit issued and outstanding under the revolving credit facility. The Company’s total available borrowing capacity under the revolving credit facility was $215.0 million as of July 31, 2020.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jul. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Letters of Credit As of July 31, 2020, the Company had $38.5 million in standby letters of credit outstanding related to facility lease obligations in San Francisco, California and Denver, Colorado, which is included in restricted cash in the accompanying condensed consolidated balance sheets. Hosting Commitments On April 30, 2020, the Company executed an amendment to its existing agreement with Amazon Web Services (“AWS”). The amended agreement was effective as of May 1, 2020 and continues through April 30, 2025. Pursuant to the amended agreement, the Company has minimum annual commitments of $75.0 million which will increase by $5.0 million annually, for a total minimum commitment of $425.0 million. As of July 31, 2020, the Company had a remaining minimum payment obligation of $410.0 million to AWS through April 30, 2025. Legal Matters The Company records a loss contingency when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. The Company also discloses material contingencies when it believes a loss is not probable but reasonably possible. Accounting for contingencies requires the Company to use judgment related to both the likelihood of a loss and the estimate of the amount or range of loss. The outcomes of the Company’s legal proceedings are inherently unpredictable and subject to significant uncertainties. For some matters for which a material loss is reasonably possible, an estimate of the amount of loss or range of losses is not possible, nor is the Company able to estimate the loss or range of losses that could potentially result from the application of non-monetary remedies. Many legal and tax contingencies can take years to be resolved. Until the final resolution of legal matters, all amounts of loss or range of losses are estimates only. The final losses the Company incurs may differ materially from these estimates. Beginning in September 2019, seven purported class action lawsuits were filed against the Company, its directors, certain of its officers, and certain investment funds associated with certain of its directors, each alleging violations of securities laws in connection with the Company’s registration statement on Form S-1 filed with the SEC (the “Registration Statement”). Six of these lawsuits were filed in the Superior Court of California for the County of San Mateo and one of these lawsuits was filed in the U.S. District Court for the Northern District of California (the “Federal Action”). In the Federal Action, captioned Dennee v. Slack Technologies, Inc., Case No. 3:19-CV-05857-SI, a lead plaintiff has been appointed and the operative complaint was filed in January 2020. In January 2020, the Company and the other defendants filed a motion to dismiss the complaint. In April 2020, the U.S. District Court for the Northern District of California granted in part and denied in part the motion to dismiss. On May 5, 2020, the Company and the other defendants filed a motion to certify the court’s order for interlocutory appeal. In May 2020, the Company and the other defendants filed a motion to certify the court’s order for interlocutory appeal. In June 2020, the U.S. District Court for the Northern District of California certified the order for interlocutory appeal. Also in June 2020, the Company and the other defendants filed a petition for permission to appeal the district court’s order to the Ninth Circuit Court of Appeals. In July 2020, the Ninth Circuit Court of Appeals granted the petition. The six state court actions were consolidated in November 2019, and the consolidated action is captioned In re Slack Technologies, Inc. Shareholder Litigation, Lead Case No. 19CIV05370 (the “State Court Action”). The operative complaint was filed in the State Court Action in December 2019. A seventh state court action was filed in June 2020, but was consolidated with the State Court Action in July 2020. The Company and the other defendants filed demurrers to the complaint in the State Court Action in February 2020. In August 2020, the Superior Court of California, County of San Mateo sustained in part and overruled in part the demurrers, and granted plaintiffs leave to file an amended complaint by October 2, 2020. The Federal Action and the State Court Action seek unspecified monetary damages and other relief on behalf of investors who purchased the Company’s Class A common stock issued pursuant and/or traceable to the Registration Statement. In April 2020, three purported stockholder derivative lawsuits were filed against certain of the Company’s officers and certain of the Company’s current and former directors in the U.S. District Courts for the District of Delaware and the Northern District of California. The case filed in the Northern District of California was dismissed and re-filed in the U.S. District Court for the District of Delaware. The derivative cases were consolidated in June 2020, and the operative complaint was designated in August 2020. Defendants’ response to the operative complaint is due on September 9, 2020. The purported stockholder derivative lawsuits allege breaches of fiduciary duty in connection with the Company’s Registration Statement. The complaints seek declarations that the defendants breached their fiduciary duties to the Company, the award of unspecified damages to the Company, and certain reforms to the Company’s governance policies. In June 2020, a lawsuit was filed against the Company in the Delaware Court of Chancery pursuant to Delaware General Corporation Law Section 220 by a stockholder, but the Company has not yet been served. The action seeks an order permitting inspection and copying of certain of the Company’s books and records. In August 2020, the plaintiff in the Section 220 action filed a motion to intervene in, and stay, the derivative actions in the U.S. District Court for the District of Delaware. The Company filed an opposition to the motion on September 3, 2020. The Company believes these lawsuits are without merit and intends to vigorously defend them. Based on the preliminary nature of the proceedings in these cases, the outcomes of these matters remain uncertain. In addition, the Company is involved from time to time in various claims and legal actions arising in the ordinary course of business. While it is not feasible to predict or determine the ultimate outcomes of these matters, the Company believes that none of these ordinary course legal proceedings will have a material adverse effect on its condensed consolidated financial statements. Indemnification Agreements

Stockholders Equity

Stockholders Equity	6 Months Ended
	Jul. 31, 2020
Equity [Abstract]
Stockholders Equity	Stockholders' Equity Common Stock The Company’s amended and restated certificate of incorporation authorizes the issuance of Class A common stock and Class B common stock. As of July 31, 2020, the Company had authorized 5.0 billion shares of Class A common stock and 700.0 million shares of Class B common stock, each at par value of $0.0001. As of July 31, 2020, 482.0 million shares of Class A common stock and 87.4 million shares of Class B common stock were issued and outstanding. Preferred Stock The Company’s board of directors has the authority, without further action by the Company’s stockholders, to issue up to 100,000,000 shares of undesignated preferred stock with rights and preferences, including voting rights, designated from time to time by the board of directors. Equity Incentive Plans The Company maintains two equity incentive plans: the 2009 Stock Plan (the “2009 Plan”) and the 2019 Stock Option and Incentive Plan (the “2019 Plan”). All shares that remain available for future grants are under the 2019 Plan. In addition, the Company offers the 2019 Employee Stock Purchase Plan (the “2019 ESPP”) to eligible employees. Stock Options A summary of stock option activity under the 2009 Plan and 2019 Plan is as follows (in thousands, except years and per share data): Number of shares Weighted-average exercise price per share Weighted-average remaining contractual term (In years) Aggregate intrinsic value Outstanding at January 31, 2020 8,425 $ 4.68 6.27 $ 135,224 Granted 1,678 24.31 Exercised (1,828) 2.52 Cancelled (193) 10.53 Outstanding at July 31, 2020 8,082 $ 9.11 6.88 $ 165,231 Stock options vested and exercisable at July 31, 2020 3,994 $ 2.22 4.81 $ 109,154 Stock options vested and expected to vest at July 31, 2020 8,082 $ 9.11 6.88 $ 165,231 As of July 31, 2020, there was $30.3 million of total unrecognized stock-based compensation related to outstanding stock options, which will be recognized over a weighted average period of 4.1 years. Restricted Stock Units and Restricted Stock Awards A summary of RSUs and Restricted Stock Awards (“RSAs”) activity under the 2009 Plan and 2019 Plan is as follows (in thousands, except per share data): Restricted stock units Restricted stock awards Number of shares Weighted-average grant date fair value Number of shares Weighted-average grant date fair value Unvested at January 31, 2020 42,002 $ 12.48 1,579 $ 8.91 Granted 10,451 26.26 — — Released (9,740) 11.29 (242) 8.92 Cancelled (2,293) 13.02 — — Unvested at July 31, 2020 40,420 $ 16.30 1,337 $ 8.91 As of July 31, 2020, there was $457.7 million of total unrecognized stock-based compensation related to unvested RSUs, which will be recognized over a weighted average period of 2.0 years. As of July 31, 2020, there was $11.3 million of total unrecognized stock-based compensation related to unvested RSAs, which will be recognized over a weighted average period of 3.3 years. 2019 Employee Stock Purchase Plan For the six months ended July 31, 2020, 820,375 shares of Class A common stock were issued under the 2019 ESPP. The Company selected the Black-Scholes option-pricing model as the method for determining the estimated fair value for the Company’s 2019 ESPP. As of July 31, 2020, total unrecognized compensation cost related to the 2019 ESPP was $1.7 million which will be amortized over a weighted average period of 0.2 years. Stock-Based Compensation The Company recorded the total stock-based compensation expense as follows (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Cost of revenue $ 2,544 $ 10,952 $ 4,898 $ 10,998 Research and development 29,157 151,405 56,576 153,040 Sales and marketing 14,917 64,772 28,992 65,154 General and administrative 10,670 58,658 20,533 60,234 Total $ 57,288 $ 285,787 $ 110,999 $ 289,426

Interest Income and Other Incom

Interest Income and Other Income, Net	6 Months Ended
	Jul. 31, 2020
Other Income and Expenses [Abstract]
Interest Income and Other Income, Net	Interest Income and Other Income, Net Interest income and other income, net consist of the following (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Interest income $ 1,775 $ 4,373 $ 4,962 $ 9,176 Unrealized gains (losses) on foreign exchange 1,057 (1,386) 1,101 (1,110) Transaction gains (losses) on foreign exchange (60) 86 (221) (848) Change in fair value of strategic investments 4,182 (124) 5,820 2,884 Other non-operating income (expense), net (2) 370 (2) 407 Interest income and other income, net $ 6,952 $ 3,319 $ 11,660 $ 10,509

Income Taxes

Income Taxes	6 Months Ended
	Jul. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company computes its provision (benefit) for income taxes by applying the estimated annual effective tax rate to pretax income or loss and adjusts the provision for discrete tax items recorded in the period. For the three months ended July 31, 2020 and 2019, the Company recorded a tax provision (benefit) of $(0.1) million and $(0.9) million on pretax losses of $73.2 million and $360.5 million, respectively. The effective tax rates for the three months ended July 31, 2020 and 2019 were 0.1% and 0.3%, respectively. For the three months ended July 31, 2020, the Company maintained a full valuation allowance on its U.S. federal, state, and certain foreign jurisdictions net deferred tax assets as it was more likely than not that those deferred tax assets would not be realized. For the six months ended July 31, 2020 and 2019, the Company recorded a tax provision (benefit) of $0.1 million and $(0.4) million on pretax losses of $(147.5) million and $391.9 million, respectively. The effective tax rates for the six months ended July 31, 2020 and 2019 were 0.0% and 0.1%, respectively. For the six months ended July 31, 2020, the Company maintained a full valuation allowance on its U.S. federal, state, and certain foreign jurisdictions net deferred tax assets as it was more likely than not that those deferred tax assets would not be realized. In March 2020, the President of the United States signed into law the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). The CARES Act, among other things, includes certain income tax provisions for individuals and corporations; however, since the Company has recorded a full valuation allowance against its deferred tax assets, these changes to U.S. tax law do not have a material impact on the Company’s provision for income taxes in its condensed consolidated financial statements. In addition, although many countries in which the Company operates have also issued some form of COVID-19 related income tax guidance, this guidance does not have material impact on provision for income taxes in its condensed consolidated financial statements as of July 31, 2020. In July 2015, the U.S. Tax Court issued an opinion favorable to Altera Corporation (“Altera”) with respect to the exclusion of stock-based compensation from its intercompany cost-sharing arrangement. In June 2019, the U.S. Court of Appeals reversed the 2015 decision of the U.S. Tax Court. In July 2019, Altera petitioned the Ninth Circuit for a rehearing of a larger panel of eleven Ninth Circuit judges. Altera’s petition for rehearing was denied in November, 2019. In February 2020, Altera filed a petition for writ of certiorari to the U.S. Supreme Court. In June 2020, the U.S. Supreme Court declined the writ of certiorari. The Company has considered the impact on its condensed consolidated financial statements which is not material after considering the valuation allowance and will continue to monitor the future developments in this case.

Net Loss per Share Attributable

Net Loss per Share Attributable to Slack Common Stockholders	6 Months Ended
	Jul. 31, 2020
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Slack Common Stockholders	Net Loss per Share Attributable to Slack Common Stockholders Basic net loss per share attributable to Slack common stockholders is computed by dividing the net loss attributable to Slack common stockholders by the weighted average number of shares of common stock outstanding during the period. Diluted loss per share is the same as basic loss per share for all years presented because the effects of potentially dilutive items were antidilutive given the Company’s net loss in each period presented. The following table presents the calculation of basic and diluted net loss per share attributable to Slack common stockholders (in thousands, except per share data): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Numerator: Net loss attributable to Slack $ (74,848) $ (359,562) $ (150,059) $ (392,894) Denominator: Weighted average common shares outstanding 564,351 368,533 560,921 249,222 Net loss per share attributable to Slack common stockholders, basic and diluted $ (0.13) $ (0.98) $ (0.27) $ (1.58) Since the Company was in a loss position for all periods presented, basic net loss per share attributable to Slack common stockholders is the same as diluted net loss per share attributable to Slack common stockholders as the inclusion of all potential common shares outstanding would have been antidilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows (in thousands): As of July 31, 2020 July 31, 2019 Shares related to convertible senior notes — — Stock options 8,082 11,149 Unvested early exercised stock options — 50 Restricted stock units 40,420 50,853 Restricted stock awards 1,337 2,297 Restricted stock 741 — Employee stock purchase plan 594 247 Total antidilutive securities 51,174 64,596 The Company had 373.4 million shares of preferred stock outstanding that were converted to shares of Class B common stock in connection with the direct listing of the Company’s Class A common stock on the New York Stock Exchange. These securities were potentially dilutive, as outstanding shares of preferred stock, through the date of conversion of June 7, 2019. The Notes will not have an impact on the Company’s diluted earnings per share until the average market price of the Company’s Class A common stock exceeds the initial conversion price of approximately $31.00 per share, as the Company intends and has the ability to settle the principal amount of the Notes in cash upon conversion. The Company is required under the treasury stock method to compute the potentially dilutive shares of Class A common stock related to the Notes for periods the Company reports net income. However, upon conversion, there will be no economic dilution from the Notes until the average market price of the Company’s Class A common stock exceeds the cap price of $48.62 per share, as exercise of the Capped Calls offsets any dilution from the Notes from the conversion price up to the cap price. Capped Calls are excluded from the calculation of diluted earnings per share, as they would be antidilutive under the treasury stock method.

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jul. 31, 2020
Accounting Policies [Abstract]
Fiscal Year	Fiscal Year The Company’s fiscal year ends on January 31. References to fiscal year 2021, for example, refer to the fiscal year ended January 31, 2021.
Basis of Presentation	Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”), regarding interim financial reporting. The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned and majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The condensed consolidated financial statements include 100% of the accounts of wholly owned and majority-owned subsidiaries and the ownership interest of minority investors is recorded as noncontrolling interest. The unaudited condensed consolidated balance sheet as of January 31, 2020 included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by U.S. GAAP on an annual reporting basis. In management's opinion, the unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the balance sheets, statements of comprehensive loss, statements of stockholders’ equity, and statements of cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full fiscal year or any future period. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 12, 2020.
Consolidation	Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and applicable rules and regulations of the Securities and Exchange Commission (“SEC”), regarding interim financial reporting. The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned and majority-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The condensed consolidated financial statements include 100% of the accounts of wholly owned and majority-owned subsidiaries and the ownership interest of minority investors is recorded as noncontrolling interest. The unaudited condensed consolidated balance sheet as of January 31, 2020 included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including certain notes required by U.S. GAAP on an annual reporting basis. In management's opinion, the unaudited condensed consolidated financial statements reflect all normal recurring adjustments necessary to present fairly the balance sheets, statements of comprehensive loss, statements of stockholders’ equity, and statements of cash flows for the interim periods, but are not necessarily indicative of the results of operations to be anticipated for the full fiscal year or any future period. These condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K filed with the SEC on March 12, 2020.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. These estimates are based on information available as of the date of the condensed consolidated financial statements. On a regular basis, management evaluates these estimates and assumptions; however, actual results could materially differ from these estimates due to risks and uncertainties, including uncertainty in the current economic environment related to the outbreak of the novel coronavirus pandemic (“COVID-19”). The Company’s most significant estimates and judgments involve revenue recognition, stock-based compensation including the estimation of fair value of common stock, valuation of strategic investments, valuation of acquired goodwill and intangibles from acquisitions, period of benefit for deferred contract acquisition costs, fair value of the liability and equity components of the Notes, and uncertain tax positions.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk primarily consist of cash and cash equivalents, restricted cash, marketable securities, and accounts receivable. For cash, cash equivalents, restricted cash, and marketable securities, the Company is exposed to credit risk in the event of default by the financial institutions to the extent of the amounts recorded on the accompanying condensed consolidated balance sheets that are in excess of federal insurance limits. For accounts receivable, the Company is exposed to credit risk in the event of nonpayment by customers to the extent of the amounts recorded on the accompanying condensed consolidated balance sheets. The Company sells its services to a wide variety of customers. If the financial condition or results of operations of any significant customers deteriorates 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.
Summary of Significant Accounting Policies and Recently Adopted Accounting Standards	Summary of Significant Accounting Policies The Company’s significant accounting policies are discussed in “Index to Consolidated Financial Statements–Note 1. Description of Business and Summary of Significant Accounting Policies” in the Notes to Consolidated Financial Statements in its Annual Report on Form 10-K filed with the SEC on March 12, 2020. There have been no significant changes to these policies during the six months ended July 31, 2020, except for the accounting policy for the Notes issued in April 2020. Convertible Senior Notes The Notes are accounted for in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) Subtopic 470-20, Debt with Conversion and Other Options . Pursuant to ASC Subtopic 470-20, issuers of certain convertible debt instruments, such as the Notes, that have a net settlement feature and may be settled wholly or partially in cash upon conversion are required to separately account for the liability (debt) and equity (conversion option) components of the instrument. The carrying amount of the liability component of the instrument is computed by estimating the fair value of a similar liability without the conversion option using a market-based approach. The amount of the equity component is then calculated by deducting the fair value of the liability component from the principal amount of the instrument. The difference between the principal amount and the liability component represents a debt discount that is amortized to interest expense over the respective term of the Notes using the effective interest rate method. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. In accounting for the issuance costs related to the Notes, the allocation of issuance costs incurred between the liability and equity components was based on their relative values. Recently Adopted Accounting Standards In June 2016, the FASB issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments - Credit Losses (Topic 326) Measurement of Credit Losses on Financial Instruments , which requires an entity to utilize a new impairment model known as the current expected credit loss (“CECL”) model to estimate its “expected credit loss” and record an allowance that, when deducted from the amortized cost basis of the financial asset, presents the net amount expected to be collected on the financial asset. The CECL model is expected to result in more timely recognition of credit losses. This guidance also requires new disclosures for financial assets measured at amortized cost, loans and available-for-sale debt securities. The Company adopted Topic 326 as of February 1, 2020. The adoption of this new standard did not have a material impact on the accompanying condensed consolidated financial statements as credit losses are not expected to be significant based on historical collection trends, the financial condition of payment partners, and external market factors. The Company will continue to actively monitor the impact of the COVID-19 on expected credit losses. In August 2018, the FASB issued ASU No. 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which aligns the accounting for implementation costs incurred in a hosting arrangement that is a service contract with the accounting for implementation costs incurred to develop or obtain internal-use software under ASC 350-40, in order to determine which costs to capitalize and recognize as an asset and which costs to expense. The Company adopted ASU No. 2018-15 as of February 1, 2020 using a prospective transition approach. The adoption of this new standard did not have a material impact on the accompanying condensed consolidated financial statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes which simplifies the accounting for income taxes by removing certain exceptions to the general principles of income taxes and reducing the cost and complexity in accounting for income taxes. The Company early adopted ASU No. 2019-12 as of February 1, 2020 using the prospective transition approach. The adoption of this new standard did not have a material impact on the accompanying condensed consolidated financial statements. Recently Issued Accounting Standards Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. ASU No. 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. ASU No. 2020-06 is effective for public companies for annual periods beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted for annual periods beginning after December 15, 2020, and interim periods within those fiscal years. The Company is currently evaluating the impact of this standard on its condensed consolidated financial statements and related disclosures.
Net Loss per Share Attributable to Slack Common Stockholders	Net Loss per Share Attributable to Slack Common StockholdersBasic net loss per share attributable to Slack common stockholders is computed by dividing the net loss attributable to Slack common stockholders by the weighted average number of shares of common stock outstanding during the period. Diluted loss per share is the same as basic loss per share for all years presented because the effects of potentially dilutive items were antidilutive given the Company’s net loss in each period presented.

Revenue and Contract Costs (Tab

Revenue and Contract Costs (Tables)	6 Months Ended
	Jul. 31, 2020
Revenue from Contract with Customer [Abstract]
Schedule of Contract Liabilities	Contract liabilities consist of deferred revenue. The changes in deferred revenue were as follows (in thousands): Three Months Ended July 31, 2020 Six Months Ended July 31, 2020 Balance, beginning of period $ 381,073 $ 376,714 Billings 217,208 423,217 Deferred revenue assumed in the Rimeto acquisition 990 990 Revenue (215,864) (417,514) Balance, end of period $ 383,407 $ 383,407
Schedule of Revenues by Geographical Area	The following table shows the Company’s revenue by geographic areas, as determined based on the billing address of its customers (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 United States $ 134,214 $ 90,734 $ 259,601 $ 175,063 International 81,650 54,239 157,913 104,731 Total $ 215,864 $ 144,973 $ 417,514 $ 279,794

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jul. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis	The following tables provide the financial instruments measured at fair value on a recurring basis, within the fair value hierarchy (in thousands): As of July 31, 2020 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 757,213 $ — $ — $ 757,213 Certificates of deposit — 145,318 — 145,318 Total cash equivalents $ 757,213 $ 145,318 $ — $ 902,531 Marketable securities: Certificates of deposit $ — $ 7,560 $ — $ 7,560 Commercial paper — 14,990 — 14,990 U.S. agency securities — 40,377 — 40,377 U.S. government securities — 30,263 — 30,263 International government securities — 8,104 — 8,104 Corporate bonds — 115,663 — 115,663 Total marketable securities $ — $ 216,957 $ — $ 216,957 Noncurrent assets: Strategic investments $ — $ — $ 42,826 $ 42,826 As of January 31, 2020 Level 1 Level 2 Level 3 Total Cash equivalents: Money market funds $ 357,524 $ — $ — $ 357,524 Commercial paper — 69,882 — 69,882 Total cash equivalents $ 357,524 $ 69,882 $ — $ 427,406 Marketable securities: Commercial paper $ — $ 19,795 $ — $ 19,795 U.S. agency securities — 29,515 — 29,515 U.S. government securities — 97,172 — 97,172 International government securities — 8,115 — 8,115 Corporate bonds — 114,996 — 114,996 Total marketable securities $ — $ 269,593 $ — $ 269,593 Noncurrent assets: Strategic investments $ — $ — $ 28,814 $ 28,814
Schedule of Level 3 Assets Measured at Fair Value on Recurring Basis	The following table presents additional information about Level 3 assets measured at fair value on a recurring basis (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Balance at beginning of period $ 34,470 $ 15,266 $ 28,814 $ 12,334 Purchases 5,007 2,370 9,025 5,470 Proceeds from liquidation (833) — (833) (3,193) Realized gains 484 — 184 2,693 Unrealized gains (losses) relating to investments still held at reporting date 3,698 (140) 5,636 192 Balance at end of period $ 42,826 $ 17,496 $ 42,826 $ 17,496

Business Combination (Tables)

Business Combination (Tables)	6 Months Ended
	Jul. 31, 2020
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition	The acquisition date fair value of the purchase price was $40.1 million, which consisted of the following (in thousands): Fair Value Cash $ 653 Fair value of Class A common stock transferred 28,060 Fair value of the pre-combination service portion of restricted stock 11,435 Total purchase price $ 40,148 The following table presents the preliminary purchase price allocation recorded in the Company’s condensed consolidated balance sheet as of July 31, 2020 (in thousands): Fair Value Cash and cash equivalents $ 7,224 Accounts receivable and other assets 732 Operating lease right-of-use assets 616 Intangible assets 7,000 Goodwill 27,606 Accounts payable and other liabilities (464) Operating lease liability (637) Deferred revenue (990) Deferred tax liability (939) Total purchase price $ 40,148
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table sets forth the components of identifiable intangible assets acquired and their estimated useful lives as of the date of acquisition (in thousands): Fair Value Useful Life Developed technology $ 4,900 3 years Customer relationships 2,100 3 years Total identifiable intangible assets $ 7,000

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jul. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Cash and Cash Equivalents and Marketable Securities	The following tables summarize the amortized cost, unrealized gains and losses, and estimated fair value of cash, cash equivalents, and marketable securities consisting of the following (in thousands): As of July 31, 2020 Amortized Unrealized Unrealized Fair value Cash and cash equivalents: Cash $ 413,864 $ — $ — $ 413,864 Money market funds 757,213 — — 757,213 Certificates of deposit 145,318 — — 145,318 Total cash and cash equivalents 1,316,395 — — 1,316,395 Marketable securities: Certificates of deposit 7,500 60 — 7,560 Commercial paper 14,944 46 — 14,990 U.S. agency securities 40,160 217 — 40,377 U.S. government securities 30,089 174 — 30,263 International government securities 8,095 9 — 8,104 Corporate bonds 114,896 767 — 115,663 Total marketable securities 215,684 1,273 — 216,957 Total cash, cash equivalents and marketable securities $ 1,532,079 $ 1,273 $ — $ 1,533,352 As of January 31, 2020 Amortized Unrealized Unrealized Fair value Cash and cash equivalents: Cash $ 71,593 $ — $ — $ 71,593 Money market funds 357,524 — — 357,524 Commercial paper 69,891 — (9) 69,882 Total cash and cash equivalents 499,008 — (9) 498,999 Marketable securities: Commercial paper 19,799 4 (8) 19,795 U.S. agency securities 29,460 55 — 29,515 U.S. government securities 97,071 102 (1) 97,172 International government securities 8,109 6 — 8,115 Corporate bonds 114,871 139 (14) 114,996 Total marketable securities 269,310 306 (23) 269,593 Total cash, cash equivalents and marketable securities $ 768,318 $ 306 $ (32) $ 768,592
Schedule of Marketable Securities by Contractual Maturity	The following table classifies marketable securities by contractual maturities (in thousands): As of July 31, 2020 January 31, 2020 Due in one year $ 157,970 $ 190,344 Due in one to two years 58,987 79,249 Total $ 216,957 $ 269,593
Schedule of Property and Equipment by Category	The following is a summary of the Company’s property and equipment by category (in thousands): As of July 31, 2020 January 31, 2020 Leasehold improvements $ 102,562 $ 98,770 Furniture and fixtures 28,347 27,384 Capitalized internal-use software costs 4,241 4,241 Computer equipment 3,783 3,183 Construction in progress 7,792 10,345 Property and equipment, gross 146,725 143,923 Less: accumulated depreciation and amortization (47,996) (41,583) Property and equipment, net $ 98,729 $ 102,340
Schedule of Intangible Assets	Intangible assets consist of the following (in thousands): July 31, 2020 Weighted-average Gross carrying Accumulated Net carrying Customer relationships 4.5 years $ 11,200 $ 2,713 $ 8,487 Developed technology 2.3 years 13,427 6,228 7,199 Patents 4.4 years 2,500 292 2,208 Assembled workforce 0.2 years 1,198 1,073 125 Total $ 28,325 $ 10,306 $ 18,019 January 31, 2020 Weighted-average Gross carrying Accumulated Net carrying Customer relationships 5.5 years $ 9,100 $ 2,004 $ 7,096 Developed technology 1.6 years 8,527 4,976 3,551 Patents 4.9 years 2,500 42 2,458 Assembled workforce 0.7 years 1,198 773 425 Total $ 21,325 $ 7,795 $ 13,530
Schedule of Expected Amortization Expense Related to Intangible Assets	As of July 31, 2020, expected amortization expense relating to intangible assets for each of the next five fiscal years and thereafter is as follows (in thousands): Year ending January 31, 2021 (6 months remaining) $ 3,308 2022 5,452 2023 4,133 2024 2,772 2025 1,758 Thereafter 596 Total $ 18,019

Operating Leases (Tables)

Operating Leases (Tables)	6 Months Ended
	Jul. 31, 2020
Leases [Abstract]
Schedule of Operating Leases, Other Information	The following table sets forth a summary of and other information pertaining to the Company’s operating leases (dollars in thousands): Six Months Ended July 31, 2020 Operating cash flows used for operating leases $ 16,371 Operating lease liabilities arising from obtaining ROU assets $ 637 Weighted average remaining terms 8.1 years Weighted average discount rate 5.2 %
Schedule of Maturities of Operating Lease Liabilities	Future minimum lease payments under non-cancelable operating leases with initial lease terms in excess of one year as of July 31, 2020 as follows (in thousands): Year ending January 31, 2021 (6 months remaining) $ 13,475 2022 38,196 2023 51,810 2024 50,421 2025 52,880 Thereafter 263,278 Gross lease payments 470,060 Less: Imputed interest (57,602) Less: Tenant improvement receivables (14,022) Less: Leases executed but not yet commenced (182,563) Present value of lease liabilities $ 215,873

Debt and Financing Arrangemen_2

Debt and Financing Arrangements (Tables)	6 Months Ended
	Jul. 31, 2020
Debt Disclosure [Abstract]
Schedule of Convertible Debt	As of July 31, 2020, the net carrying amount of the liability component of the Notes was as follows (in thousands): Principal $ 862,500 Less: unamortized discount (217,282) Less: unamortized issuance costs (14,892) Net carrying amount $ 630,326 As of July 31, 2020, the net carrying amount of the equity component of the Notes was as follows (in thousands): Proceeds allocated to the conversion options (debt discount) $ 229,249 Less: issuance costs (5,627) Carrying amount of the equity component $ 223,622 The following table sets forth the interest expense recognized related to the Notes (in thousands): Three Months Ended July 31, 2020 Six Months Ended July 31, 2020 Contractual interest expense $ 1,078 $ 1,330 Amortization of debt discount 9,722 11,967 Amortization of debt issuance costs 531 652 Total interest expense related to the Senior Notes $ 11,331 $ 13,949

Stockholders Equity (Tables)

Stockholders Equity (Tables)	6 Months Ended
	Jul. 31, 2020
Equity [Abstract]
Schedule of Stock Options Activity	A summary of stock option activity under the 2009 Plan and 2019 Plan is as follows (in thousands, except years and per share data): Number of shares Weighted-average exercise price per share Weighted-average remaining contractual term (In years) Aggregate intrinsic value Outstanding at January 31, 2020 8,425 $ 4.68 6.27 $ 135,224 Granted 1,678 24.31 Exercised (1,828) 2.52 Cancelled (193) 10.53 Outstanding at July 31, 2020 8,082 $ 9.11 6.88 $ 165,231 Stock options vested and exercisable at July 31, 2020 3,994 $ 2.22 4.81 $ 109,154 Stock options vested and expected to vest at July 31, 2020 8,082 $ 9.11 6.88 $ 165,231
Schedule of Restricted Stock Units and Restricted Stock Activity	A summary of RSUs and Restricted Stock Awards (“RSAs”) activity under the 2009 Plan and 2019 Plan is as follows (in thousands, except per share data): Restricted stock units Restricted stock awards Number of shares Weighted-average grant date fair value Number of shares Weighted-average grant date fair value Unvested at January 31, 2020 42,002 $ 12.48 1,579 $ 8.91 Granted 10,451 26.26 — — Released (9,740) 11.29 (242) 8.92 Cancelled (2,293) 13.02 — — Unvested at July 31, 2020 40,420 $ 16.30 1,337 $ 8.91
Schedule of Stock-Based Compensation Expense	The Company recorded the total stock-based compensation expense as follows (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Cost of revenue $ 2,544 $ 10,952 $ 4,898 $ 10,998 Research and development 29,157 151,405 56,576 153,040 Sales and marketing 14,917 64,772 28,992 65,154 General and administrative 10,670 58,658 20,533 60,234 Total $ 57,288 $ 285,787 $ 110,999 $ 289,426

Interest Income and Other Inc_2

Interest Income and Other Income, Net (Tables)	6 Months Ended
	Jul. 31, 2020
Other Income and Expenses [Abstract]
Schedule of Interest Income and Other Income, Net	Interest income and other income, net consist of the following (in thousands): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Interest income $ 1,775 $ 4,373 $ 4,962 $ 9,176 Unrealized gains (losses) on foreign exchange 1,057 (1,386) 1,101 (1,110) Transaction gains (losses) on foreign exchange (60) 86 (221) (848) Change in fair value of strategic investments 4,182 (124) 5,820 2,884 Other non-operating income (expense), net (2) 370 (2) 407 Interest income and other income, net $ 6,952 $ 3,319 $ 11,660 $ 10,509

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Slack Common Stockholders (Tables)	6 Months Ended
	Jul. 31, 2020
Earnings Per Share [Abstract]
Schedule Calculation of Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss per share attributable to Slack common stockholders (in thousands, except per share data): Three Months Ended July 31, Six Months Ended July 31, 2020 2019 2020 2019 Numerator: Net loss attributable to Slack $ (74,848) $ (359,562) $ (150,059) $ (392,894) Denominator: Weighted average common shares outstanding 564,351 368,533 560,921 249,222 Net loss per share attributable to Slack common stockholders, basic and diluted $ (0.13) $ (0.98) $ (0.27) $ (1.58)
Schedule of Potentially Dilutive Securities Excluded from Diluted Per Share Calculations	Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows (in thousands): As of July 31, 2020 July 31, 2019 Shares related to convertible senior notes — — Stock options 8,082 11,149 Unvested early exercised stock options — 50 Restricted stock units 40,420 50,853 Restricted stock awards 1,337 2,297 Restricted stock 741 — Employee stock purchase plan 594 247 Total antidilutive securities 51,174 64,596

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies (Details) - Convertible Debt $ in Millions	Apr. 09, 2020USD ($)
Debt Instrument [Line Items]
Aggregate principal amount	$ 862.5
Stated interest percentage	0.50%

Revenue and Contract Costs - Sc

Revenue and Contract Costs - Schedule of Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jul. 31, 2020	Jul. 31, 2020
Contract With Customer, Liability [Roll Forward]
Balance, beginning of period	$ 381,073	$ 376,714
Billings	217,208	423,217
Deferred revenue assumed in the Rimeto acquisition	990	990
Revenue	(215,864)	(417,514)
Balance, end of period	$ 383,407	$ 383,407

Revenue and Contract Costs - Na

Revenue and Contract Costs - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019	Jan. 31, 2020
Revenue from Contract with Customer [Abstract]
Deferred incremental costs of obtaining a contract	$ 5,400	$ 6,000	$ 18,000	$ 10,800
Deferred commissions, net included in prepaid expenses and other current assets	15,600		15,600		$ 11,200
Deferred commissions, net included in other assets	28,100		28,100		$ 21,400
Amortization of deferred contract acquisition costs	3,800	1,800	6,898	3,290
Impairment loss related to deferred costs	$ 0	$ 0	$ 0	$ 0

Revenue and Contract Costs - Re

Revenue and Contract Costs - Remaining Performance Obligations (Details) $ in Millions	Jul. 31, 2020USD ($)
Revenue from Contract with Customer [Abstract]
Future estimated revenue related to unsatisfied or partially satisfied performance obligations	$ 388.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-08-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations expected to be recognized (as a percent)	57.00%
Performance obligations expected to be satisfied, expected timing	12 months

Revenue and Contract Costs - _2

Revenue and Contract Costs - Schedule of Revenue by Geographic Areas (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 215,864	$ 144,973	$ 417,514	$ 279,794
United States
Disaggregation of Revenue [Line Items]
Total revenues	134,214	90,734	259,601	175,063
International
Disaggregation of Revenue [Line Items]
Total revenues	$ 81,650	$ 54,239	$ 157,913	$ 104,731

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 216,957	$ 269,593
Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	757,213	357,524
Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	145,318
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		69,882
Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	902,531	427,406
Marketable securities	216,957	269,593
Strategic investments	42,826	28,814
Fair Value, Recurring | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	7,560
Fair Value, Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	14,990	19,795
Fair Value, Recurring | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	40,377	29,515
Fair Value, Recurring | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	30,263	97,172
Fair Value, Recurring | International government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	8,104	8,115
Fair Value, Recurring | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	115,663	114,996
Fair Value, Recurring | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	757,213	357,524
Fair Value, Recurring | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	145,318
Fair Value, Recurring | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		69,882
Fair Value, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	757,213	357,524
Marketable securities	0	0
Strategic investments	0	0
Fair Value, Recurring | Level 1 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0
Fair Value, Recurring | Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 1 | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 1 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 1 | International government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 1 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	757,213	357,524
Fair Value, Recurring | Level 1 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0
Fair Value, Recurring | Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0
Fair Value, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	145,318	69,882
Marketable securities	216,957	269,593
Strategic investments	0	0
Fair Value, Recurring | Level 2 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	7,560
Fair Value, Recurring | Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	14,990	19,795
Fair Value, Recurring | Level 2 | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	40,377	29,515
Fair Value, Recurring | Level 2 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	30,263	97,172
Fair Value, Recurring | Level 2 | International government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	8,104	8,115
Fair Value, Recurring | Level 2 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	115,663	114,996
Fair Value, Recurring | Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Recurring | Level 2 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	145,318
Fair Value, Recurring | Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		69,882
Fair Value, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Marketable securities	0	0
Strategic investments	42,826	28,814
Fair Value, Recurring | Level 3 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0
Fair Value, Recurring | Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 3 | U.S. agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 3 | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 3 | International government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 3 | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	0	0
Fair Value, Recurring | Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Recurring | Level 3 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0
Fair Value, Recurring | Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		$ 0

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Level 3 Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 34,470	$ 15,266	$ 28,814	$ 12,334
Purchases	5,007	2,370	9,025	5,470
Proceeds from liquidation	(833)	0	(833)	(3,193)
Realized gains	484	0	184	2,693
Unrealized gains (losses) relating to investments still held at reporting date	3,698	(140)	5,636	192
Balance at end of period	$ 42,826	$ 17,496	$ 42,826	$ 17,496

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) $ in Millions	Jul. 31, 2020USD ($)
Shares related to convertible senior notes | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of convertible senior notes	$ 1,040

Business Combination - Narrativ

Business Combination - Narrative (Details) - Rimeto - USD ($) $ in Thousands	Jun. 29, 2020	Jul. 31, 2020	Jul. 31, 2020
Business Acquisition [Line Items]
Post-combination stock based compensation	$ 11,400
Total purchase price	$ 40,148
General and administrative
Business Acquisition [Line Items]
Acquisition related costs		$ 1,500	$ 1,500
Restricted stock units
Business Acquisition [Line Items]
Award vesting period (in years)	4 years
Post-combination stock based compensation	$ 19,000
Restricted stock
Business Acquisition [Line Items]
Award vesting period (in years)	4 years
Common Stock
Business Acquisition [Line Items]
Shares issued during period (in shares)	1,659,715
Shares subject to re-vesting restriction (in shares)	740,837

Business Combination - Fair Val

Business Combination - Fair Value of Consideration Transferred (Details) - Rimeto $ in Thousands	Jun. 29, 2020USD ($)
Business Acquisition [Line Items]
Cash	$ 653
Fair value of Class A common stock transferred	28,060
Fair value of the pre-combination service portion of restricted stock	11,435
Total purchase price	$ 40,148

Business Combination - Prelimin

Business Combination - Preliminary Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 76,204	$ 48,598
Rimeto
Business Acquisition [Line Items]
Cash and cash equivalents	7,224
Accounts receivable and other assets	732
Operating lease right-of-use assets	616
Intangible assets	7,000
Goodwill	27,606
Accounts payable and other liabilities	(464)
Operating lease liability	(637)
Deferred revenue	(990)
Deferred tax liability	(939)
Total purchase price	$ 40,148

Business Combination - Identifi

Business Combination - Identifiable Intangible Assets Acquired (Details) - Rimeto $ in Thousands	6 Months Ended
	Jul. 31, 2020USD ($)
Business Acquisition [Line Items]
Fair Value	$ 7,000
Developed technology
Business Acquisition [Line Items]
Fair Value	$ 4,900
Useful Life	3 years
Customer relationships
Business Acquisition [Line Items]
Fair Value	$ 2,100
Useful Life	3 years

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Cash and Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, amortized cost	$ 1,316,395	$ 498,999
Marketable securities, amortized cost	215,684	269,310
Marketable securities, unrealized gains	1,273	306
Marketable securities, unrealized losses	0	(23)
Marketable securities, fair value	216,957	269,593
Total cash, cash equivalents and marketable securities, amortized cost	1,532,079	768,318
Total cash, cash equivalents and marketable securities, unrealized gains	1,273	306
Total cash, cash equivalents and marketable securities, unrealized losses	0	(32)
Total cash, cash equivalents and marketable securities, fair value	1,533,352	768,592
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Marketable securities, amortized cost	7,500
Marketable securities, unrealized gains	60
Marketable securities, unrealized losses	0
Marketable securities, fair value	7,560
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Marketable securities, amortized cost	14,944	19,799
Marketable securities, unrealized gains	46	4
Marketable securities, unrealized losses	0	(8)
Marketable securities, fair value	14,990	19,795
U.S. agency securities
Debt Securities, Available-for-sale [Line Items]
Marketable securities, amortized cost	40,160	29,460
Marketable securities, unrealized gains	217	55
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	40,377	29,515
U.S. government securities
Debt Securities, Available-for-sale [Line Items]
Marketable securities, amortized cost	30,089	97,071
Marketable securities, unrealized gains	174	102
Marketable securities, unrealized losses	0	(1)
Marketable securities, fair value	30,263	97,172
International government securities
Debt Securities, Available-for-sale [Line Items]
Marketable securities, amortized cost	8,095	8,109
Marketable securities, unrealized gains	9	6
Marketable securities, unrealized losses	0	0
Marketable securities, fair value	8,104	8,115
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Marketable securities, amortized cost	114,896	114,871
Marketable securities, unrealized gains	767	139
Marketable securities, unrealized losses	0	(14)
Marketable securities, fair value	115,663	114,996
Total cash and cash equivalents
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, amortized cost	1,316,395	499,008
Cash and cash equivalents, unrealized gains	0	0
Cash and cash equivalents, unrealized losses	0	(9)
Cash and cash equivalents, fair value	1,316,395	498,999
Cash
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, amortized cost	413,864	71,593
Cash and cash equivalents, fair value	413,864	71,593
Money market funds
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, amortized cost	757,213	357,524
Cash and cash equivalents, fair value	757,213	357,524
Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, amortized cost	145,318
Cash and cash equivalents, fair value	$ 145,318
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Cash and cash equivalents, amortized cost		69,891
Cash and cash equivalents, unrealized gains		0
Cash and cash equivalents, unrealized losses		(9)
Cash and cash equivalents, fair value		$ 69,882

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Marketable Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Due in one year	$ 157,970	$ 190,344
Due in one to two years	58,987	79,249
Total	$ 216,957	$ 269,593

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Property and Equipment by Category (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 146,725	$ 143,923
Less: accumulated depreciation and amortization	(47,996)	(41,583)
Property and equipment, net	98,729	102,340
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	102,562	98,770
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, gross	28,347	27,384
Capitalized internal-use software costs
Property, Plant and Equipment [Line Items]
Property and equipment, gross	4,241	4,241
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	3,783	3,183
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 7,792	$ 10,345

Balance Sheet Components - Narr

Balance Sheet Components - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019	Jan. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Depreciation	$ 5,600,000	$ 5,800,000	$ 11,100,000	$ 10,600,000
Goodwill	76,204,000		76,204,000		$ 48,598,000
Amortization expense of intangible assets	1,400,000	1,100,000	2,500,000	2,100,000
Goodwill impairment	0	$ 0	0	$ 0
Rimeto
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 27,606,000		$ 27,606,000

Balance Sheet Components - Sc_4

Balance Sheet Components - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Apr. 30, 2020	Jul. 31, 2020	Jan. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		$ 28,325	$ 21,325
Accumulated amortization		10,306	7,795
Net carrying amount		18,019	13,530
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		11,200	9,100
Accumulated amortization		2,713	2,004
Net carrying amount		8,487	7,096
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		13,427	8,527
Accumulated amortization		6,228	4,976
Net carrying amount		7,199	3,551
Patents
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		2,500	2,500
Accumulated amortization		292	42
Net carrying amount		2,208	2,458
Assembled workforce
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount		1,198	1,198
Accumulated amortization		1,073	773
Net carrying amount		$ 125	$ 425
Weighted Average | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	5 years 6 months	4 years 6 months
Weighted Average | Developed technology
Finite-Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	1 year 7 months 6 days	2 years 3 months 18 days
Weighted Average | Patents
Finite-Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	4 years 10 months 24 days	4 years 4 months 24 days
Weighted Average | Assembled workforce
Finite-Lived Intangible Assets [Line Items]
Weighted-average remaining amortization period	8 months 12 days	2 months 12 days

Balance Sheet Components - Sc_5

Balance Sheet Components - Schedule of Expected Amortization Expense (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2021 (6 months remaining)	$ 3,308
2022	5,452
2023	4,133
2024	2,772
2025	1,758
Thereafter	596
Net carrying amount	$ 18,019	$ 13,530

Operating Leases - Narrative (D

Operating Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Leases [Abstract]
Operating lease costs	$ 10,900		$ 21,800
Variable lease costs	1,600		2,900
Short-term lease costs	800		1,500
Rent expense, net of sublease income		$ 8,700		$ 17,000
Lessee, Lease, Description [Line Items]
Operating lease costs	10,900		21,800
Rent expense, net of sublease income		$ 8,700		$ 17,000
Commitments for operating leases that have not yet commenced	$ 182,563		$ 182,563
Minimum
Lessee, Lease, Description [Line Items]
Operating leases that have not yet commenced, term of lease	9 years 10 months 24 days		9 years 10 months 24 days
Maximum
Lessee, Lease, Description [Line Items]
Operating leases that have not yet commenced, term of lease	12 years		12 years

Operating Leases - Schedule of

Operating Leases - Schedule of Operating Lease Costs (Details) $ in Thousands	6 Months Ended
	Jul. 31, 2020USD ($)
Leases [Abstract]
Operating cash flows used for operating leases	$ 16,371
Operating lease liabilities arising from obtaining ROU assets	$ 637
Weighted average remaining terms	8 years 1 month 6 days
Weighted average discount rate	5.20%

Operating Leases - Schedule o_2

Operating Leases - Schedule of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Jul. 31, 2020USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021 (6 months remaining)	$ 13,475
2022	38,196
2023	51,810
2024	50,421
2025	52,880
Thereafter	263,278
Gross lease payments	470,060
Less: Imputed interest	(57,602)
Less: Tenant improvement receivables	(14,022)
Less: Leases executed but not yet commenced	(182,563)
Present value of lease liabilities	$ 215,873

Debt and Financing Arrangemen_3

Debt and Financing Arrangements - Narrative (Details) $ / shares in Units, shares in Millions	Apr. 09, 2020USD ($)numberOfDays$ / sharesshares	May 30, 2019USD ($)	Jul. 31, 2020USD ($)
Convertible Debt
Line of Credit Facility [Line Items]
Aggregate principal amount	$ 862,500,000
Additional amount available for purchase	112,500,000
Total net proceeds from debt offering	$ 841,300,000
Stated interest percentage	0.50%
Limitation on sale of common stock, sale price threshold, number of trading days | numberOfDays	20
Limitation on sale of common stock, sale price threshold, trading period | numberOfDays	30
Threshold percentage of stock price trigger	130.00%
Percentage of closing sale price in excess of convertible notes	98.00%
Conversion rate	0.032263
Conversion price (in dollars per share) | $ / shares	$ 31
Redemption price percentage	100.00%
Percentage of aggregate principal amount	25.00%
Carrying amount of equity component	$ 229,200,000		$ 229,249,000
Initial cap price (in dollars per share) | $ / shares	$ 48.62
Number of shares covered in capped call transaction | shares	27.8
Net cost incurred to purchase capped call transactions	$ 105,600,000
Convertible Debt | Discount Rate
Line of Credit Facility [Line Items]
Measurement input	0.0685
Line of Credit | Revolving Credit Facility
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 215,000,000
Potential increase in limit of aggregate commitments		$ 200,000,000
Potential increase in limit of aggregate commitments, as a percentage of adjusted EBITDA		100.00%
Commitment fee percentage		0.10%
Annual fee percentage		1.25%
Fronting fee percentage		0.125%
Letter of credit amount issued			0
Remaining borrowing capacity			$ 215,000,000
Line of Credit | Prime Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.25%
Line of Credit | LIBOR | Revolving Credit Facility
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.25%

Debt and Financing Arrangemen_4

Debt and Financing Arrangements - Schedule of Net Carrying Amount of Liability Component (Details) - Convertible Debt $ in Thousands	Jul. 31, 2020USD ($)
Debt Instrument [Line Items]
Principal	$ 862,500
Less: unamortized discount	(217,282)
Less: unamortized issuance costs	(14,892)
Net carrying amount	$ 630,326

Debt and Financing Arrangemen_5

Debt and Financing Arrangements - Schedule of Carrying Amount of Equity Component (Details) - Convertible Debt - USD ($) $ in Thousands	Jul. 31, 2020	Apr. 09, 2020
Debt Instrument [Line Items]
Proceeds allocated to the conversion options (debt discount)	$ 229,249	$ 229,200
Less: issuance costs	(5,627)
Carrying amount of the equity component	$ 223,622

Debt and Financing Arrangemen_6

Debt and Financing Arrangements - Schedule of Interest Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Debt Instrument [Line Items]
Amortization of debt issuance costs			$ 12,619	$ 0
Total interest expense related to the Senior Notes	$ 11,552	$ 208	14,394	$ 321
Convertible Debt
Debt Instrument [Line Items]
Contractual interest expense	1,078		1,330
Amortization of debt discount	9,722		11,967
Amortization of debt issuance costs	531		652
Total interest expense related to the Senior Notes	$ 11,331		$ 13,949

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($)	Apr. 30, 2020	Apr. 30, 2018	Jul. 31, 2020
Long-term Purchase Commitment [Line Items]
Letter of credit amount outstanding			$ 38,500,000
Hosting Commitments
Long-term Purchase Commitment [Line Items]
Minimum annual commitment amount under hosting commitments	$ 75,000,000
Increase in annual commitment amount under hosting commitments	$ 5,000,000
Total minimum commitment amount under hosting commitments		$ 425,000,000
Purchase Obligation			$ 410,000,000

Stockholders Equity - Narrative

Stockholders Equity - Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2020USD ($)$ / sharesshares	Jul. 31, 2020USD ($)plan$ / sharesshares
Class of Stock [Line Items]
Preferred stock, number of shares authorized (in shares)	100,000,000	100,000,000
Number of equity incentive plans | plan		2
Unrecognized stock based compensation expense related to options | $	$ 30.3	$ 30.3
Stock options
Class of Stock [Line Items]
Unrecognized stock based compensation expense related to options, weighted average period of recognition		4 years 1 month 6 days
Restricted stock units
Class of Stock [Line Items]
Unrecognized stock based compensation expense related to options, weighted average period of recognition		2 years
Unrecognized stock based compensation expense | $	457.7	$ 457.7
Restricted stock
Class of Stock [Line Items]
Unrecognized stock based compensation expense related to options, weighted average period of recognition		3 years 3 months 18 days
Unrecognized stock based compensation expense | $	$ 11.3	$ 11.3
Class A Common Stock
Class of Stock [Line Items]
Number of shares authorized for issuance (in shares)	5,000,000,000	5,000,000,000
Par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Number of shares issued (in shares)	482,000,000	482,000,000
Number of shares outstanding (in shares)	482,000,000	482,000,000
Class B Common Stock
Class of Stock [Line Items]
Number of shares authorized for issuance (in shares)	700,000,000	700,000,000
Par value (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Number of shares issued (in shares)	87,400,000	87,400,000
Number of shares outstanding (in shares)	87,400,000	87,400,000
2019 Employee Stock Purchase Plan | Class A Common Stock
Class of Stock [Line Items]
Number of shares issued under employee stock purchase plan (in shares)	820,375,000
2019 Employee Stock Purchase Plan | Class A Common Stock | Employee stock purchase plan
Class of Stock [Line Items]
Unrecognized stock based compensation expense related to options, weighted average period of recognition		2 months 12 days
Unrecognized stock based compensation expense | $	$ 1.7	$ 1.7

Stockholders Equity - Schedule

Stockholders Equity - Schedule of Stock Options (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jul. 31, 2020USD ($)$ / sharesshares	Jan. 31, 2020USD ($)$ / sharesshares
Number of shares
Outstanding at beginning of period (in shares) | shares	8,425
Granted (in shares) | shares	1,678
Exercised (in shares) | shares	(1,828)
Cancelled (in shares) | shares	(193)
Outstanding at end of period (in shares) | shares	8,082	8,425
Stock options vested and exercisable at end of period, number of shares (in shares) | shares	3,994
Stock options vested and expected to vest at end of period, number of shares (in shares) | shares	8,082
Weighted-average exercise price per share
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 4.68
Granted (in dollars per share) | $ / shares	24.31
Exercised (in dollars per share) | $ / shares	2.52
Cancelled (in dollars per share) | $ / shares	10.53
Outstanding at end of period (in dollars per share) | $ / shares	9.11	$ 4.68
Stock options vested and exercisable at end of period, weighted-average exercise price per share (in dollars per share) | $ / shares	2.22
Stock options vested and expected to vest at end of period, weighted-average exercise price per share (in dollars per share) | $ / shares	$ 9.11
Weighted-average remaining contractual term (In years)
Outstanding, weighted-average remaining contractual term	6 years 10 months 17 days	6 years 3 months 7 days
Stock options vested and exercisable, weighted-average remaining contractual term	4 years 9 months 21 days
Stock options vested and expected to vest, weighted-average remaining contractual term	6 years 10 months 17 days
Aggregate intrinsic value
Outstanding, aggregate intrinsic value | $	$ 165,231	$ 135,224
Stock options vested and exercisable, aggregate intrinsic value | $	109,154
Stock options vested and expected to vest, aggregate intrinsic value | $	$ 165,231

Stockholders Equity - Schedul_2

Stockholders Equity - Schedule of Restricted Stock Units and Restricted Stock Awards (Details) shares in Thousands	6 Months Ended
	Jul. 31, 2020$ / sharesshares
Restricted stock units
Number of shares
Unvested at beginning of period (in shares) | shares	42,002
Granted (in shares) | shares	10,451
Released (in shares) | shares	(9,740)
Cancelled (in shares) | shares	(2,293)
Unvested at end of period (in shares) | shares	40,420
Weighted-average grant date fair value per share
Unvested at beginning of period (in dollars per share) | $ / shares	$ 12.48
Granted (in dollars per share) | $ / shares	26.26
Released (in dollars per share) | $ / shares	11.29
Cancelled (in dollars per share) | $ / shares	13.02
Unvested at end of period (in dollars per share) | $ / shares	$ 16.30
Restricted stock
Number of shares
Unvested at beginning of period (in shares) | shares	1,579
Granted (in shares) | shares	0
Released (in shares) | shares	(242)
Cancelled (in shares) | shares	0
Unvested at end of period (in shares) | shares	1,337
Weighted-average grant date fair value per share
Unvested at beginning of period (in dollars per share) | $ / shares	$ 8.91
Granted (in dollars per share) | $ / shares	0
Released (in dollars per share) | $ / shares	8.92
Cancelled (in dollars per share) | $ / shares	0
Unvested at end of period (in dollars per share) | $ / shares	$ 8.91

Stockholders Equity - Schedul_3

Stockholders Equity - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 57,288	$ 285,787	$ 110,999	$ 289,426
Cost of revenue
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	2,544	10,952	4,898	10,998
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	29,157	151,405	56,576	153,040
Sales and marketing
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	14,917	64,772	28,992	65,154
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 10,670	$ 58,658	$ 20,533	$ 60,234

Interest Income and Other Inc_3

Interest Income and Other Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Other Income and Expenses [Abstract]
Interest income	$ 1,775	$ 4,373	$ 4,962	$ 9,176
Unrealized gains (losses) on foreign exchange	1,057	(1,386)	1,101	(1,110)
Transaction gains (losses) on foreign exchange	(60)	86	(221)	(848)
Change in fair value of strategic investments	4,182	(124)	5,820	2,884
Other non-operating income (expense), net	(2)	370	(2)	407
Interest income and other income, net	$ 6,952	$ 3,319	$ 11,660	$ 10,509

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Income Tax Disclosure [Abstract]
Provision (benefit) for income taxes	$ (81)	$ (923)	$ 61	$ (403)
Pretax losses	$ 73,234	$ 360,539	$ 147,519	$ 391,900
Effective tax rate	0.10%	0.30%	(0.00%)	0.10%

Net Loss per Share Attributab_3

Net Loss per Share Attributable to Slack Common Stockholders - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Numerator:
Net loss attributable to Slack	$ (74,848)	$ (359,562)	$ (150,059)	$ (392,894)
Denominator:
Weighted average common shares outstanding (in shares)	564,351	368,533	560,921	249,222
Net loss per share attributable to Slack common stockholders, basic and diluted (in dollars per share)	$ (0.13)	$ (0.98)	$ (0.27)	$ (1.58)

Net Loss per Share Attributab_4

Net Loss per Share Attributable to Slack Common Stockholders - Potentially Dilutive Securities Excluded from Diluted Per Share Calculations (Details) - shares shares in Thousands	Jun. 07, 2019	Jul. 31, 2020	Jul. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		51,174	64,596
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)	373,400
Shares related to convertible senior notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		0	0
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		8,082	11,149
Unvested early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		0	50
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		40,420	50,853
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		1,337	2,297
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		741	0
Employee stock purchase plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total antidilutive securities (in shares)		594	247

Net Loss per Share Attributab_5

Net Loss per Share Attributable to Slack Common Stockholders - Narrative (Details) - $ / shares shares in Thousands	Jun. 07, 2019	Jul. 31, 2020	Jul. 31, 2019	Apr. 09, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities converted from convertible preferred stock to common stock (in shares)		51,174	64,596
Convertible Debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion price (in dollars per share)				$ 31
Initial cap price (in dollars per share)				$ 48.62
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities converted from convertible preferred stock to common stock (in shares)	373,400