CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Cash flows from operating activities:
Net loss	$ (539,102)	$ (348,535)	$ (178,028)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	9,826	3,522	1,362
Non-cash operating lease costs	33,475	27,712	3,172
Amortization of deferred commissions	28,841	16,986	5,674
Stock-based compensation included in capitalized software development costs	301,441	78,399	22,409
Net amortization (accretion) of premiums (discounts) on investments	8,630	(5,459)	(5,011)
Other	4,580	1,476	221
Changes in operating assets and liabilities, net of effect of acquisitions:
Accounts receivable	(116,289)	(116,869)	(51,421)
Deferred commissions	(51,444)	(68,595)	(36,344)
Prepaid expenses and other assets	(62,349)	(10,811)	(9,091)
Accounts payable	(2,878)	1,116	5,170
Accrued expenses and other liabilities	58,252	34,994	20,811
Operating lease liabilities	(31,281)	(13,455)	(2,537)
Deferred revenue	312,881	222,961	79,631
Net cash used in operating activities	(45,417)	(176,558)	(143,982)
Cash flows from investing activities:
Purchases of property and equipment	(35,037)	(18,583)	(2,058)
Capitalized internal-use software development costs	(5,293)	(4,265)	(1,958)
Cash paid for acquisitions, net of cash acquired	(6,035)	(6,314)	0
Purchases of intangible assets	(8,374)	0	0
Purchases of investments	(4,859,852)	(622,854)	(738,383)
Sales of investments	177,070	14,087	0
Maturities and redemptions of investments	700,876	776,424	379,757
Net cash (used in) provided by investing activities	(4,036,645)	138,495	(362,642)
Cash flows from financing activities:
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	478,573	24,121	438,227
Proceeds from initial public offering and private placements, net of underwriting discounts	4,242,284	0	0
Proceeds from early exercised stock options	159	6,213	2,754
Proceeds from exercise of stock options	53,378	27,526	2,264
Proceeds from repayments of a nonrecourse promissory note	2,090	0	0
Repurchases of common stock in connection with issuer tender offers	0	0	(29,644)
Repurchases of early exercised stock options and restricted common stock	(30)	(391)	0
Payments of deferred purchase consideration for acquisitions	(1,164)	0	0
Net cash provided by financing activities	4,775,290	57,469	413,601
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(11)	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	693,217	19,406	(93,023)
Cash, cash equivalents and restricted cash—Beginning of period	141,976	122,570	215,593
Cash, cash equivalents and restricted cash—End of period	835,193	141,976	122,570
Supplemental disclosures of cash flow information:
Cash paid for income taxes	1,195	1,428	235
Supplemental disclosures of non-cash investing and financing activities:
Property and equipment included in accounts payable and accrued expenses	6,941	589	1,072
Stock-based compensation included in capitalized software development costs	2,072	1,080	577
Vesting of early exercised stock options and restricted common stock	3,502	5,791	1,807
Deferred purchase consideration for acquisitions	1,065	1,164	0
Equity consideration in connection with an acquisition	0	4,749	0
Reconciliation of cash, cash equivalents and restricted cash:
Total cash, cash equivalents and restricted cash	$ 141,976	$ 122,570	$ 122,570