CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($) $ in Thousands		Total	Common Stock		Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Jan. 31, 2020		169,921,272
Beginning balance at Jan. 31, 2020		$ 936,474
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of redeemable convertible preferred stock (in shares)		12,349,827
Issuance of redeemable convertible preferred stock		$ 478,573
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		(182,271,099)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering		$ (1,415,047)
Ending balance (in shares) at Oct. 31, 2020		0
Ending balance at Oct. 31, 2020		$ 0
Beginning balance (in shares) at Jan. 31, 2020			55,452,421
Beginning balance at Jan. 31, 2020		(544,757)	$ 6		$ 155,340	$ 216	$ (700,319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)			182,271,099
Conversion of redeemable convertible preferred stock to common stock upon initial public offering		1,415,047	$ 18		1,415,029
Issuance of common stock upon initial public offering and private placements, net of underwriting discounts (in shares)			36,366,666
Issuance of common stock upon initial public offering and private placements, net of underwriting discounts		4,242,284	$ 4		4,242,280
Issuance of common stock upon exercise of stock options (in shares)			9,031,461
Issuance of common stock upon exercise of stock options		31,098			31,098
Exercise of common stock warrants (in shares)			32,241
Repurchase of early exercised stock options (in shares)			(40,000)
Vesting of early exercised stock options and restricted common stock		5,341			5,341
Vesting of restricted stock units (in shares)			5,657
Stock-based compensation		158,810			158,810
Other comprehensive income (loss)		159				159
Net loss		(340,167)					(340,167)
Ending balance (in shares) at Oct. 31, 2020			283,119,545
Ending balance at Oct. 31, 2020		$ 4,967,815	$ 28		6,007,898	375	(1,040,486)
Beginning balance (in shares) at Jul. 31, 2020		182,271,099
Beginning balance at Jul. 31, 2020		$ 1,415,047
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)		(182,271,099)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering		$ (1,415,047)
Ending balance (in shares) at Oct. 31, 2020		0
Ending balance at Oct. 31, 2020		$ 0
Beginning balance (in shares) at Jul. 31, 2020			62,257,063
Beginning balance at Jul. 31, 2020		(651,399)	$ 6		219,046	1,146	(871,597)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)			182,271,099
Conversion of redeemable convertible preferred stock to common stock upon initial public offering		1,415,047	$ 18		1,415,029
Issuance of common stock upon initial public offering and private placements, net of underwriting discounts (in shares)			36,366,666
Issuance of common stock upon initial public offering and private placements, net of underwriting discounts		4,242,284	$ 4		4,242,280
Issuance of common stock upon exercise of stock options (in shares)			2,186,819
Issuance of common stock upon exercise of stock options		10,362			10,362
Exercise of common stock warrants (in shares)			32,241
Vesting of early exercised stock options and restricted common stock		1,756			1,756
Vesting of restricted stock units (in shares)			5,657
Stock-based compensation		119,425			119,425
Other comprehensive income (loss)		(771)				(771)
Net loss		(168,889)					(168,889)
Ending balance (in shares) at Oct. 31, 2020			283,119,545
Ending balance at Oct. 31, 2020		$ 4,967,815	$ 28		6,007,898	375	(1,040,486)
Beginning balance (in shares) at Jan. 31, 2021		0
Beginning balance at Jan. 31, 2021		$ 0
Ending balance (in shares) at Oct. 31, 2021		0
Ending balance at Oct. 31, 2021		$ 0
Beginning balance (in shares) at Jan. 31, 2021	[1]		287,917,604
Beginning balance at Jan. 31, 2021		4,936,471	$ 28	[1]	6,175,425	439	(1,239,421)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]		15,278,682
Issuance of common stock upon exercise of stock options		90,376	$ 2	[1]	90,374
Issuance of common stock under employee stock purchase plan (in shares)	[1]		370,452
Issuance of common stock under employee stock purchase plan		52,227			52,227
Vesting of early exercised stock options and restricted common stock		614			614
Vesting of restricted stock units (in shares)	[1]		2,332,748
Stock-based compensation		478,714			478,714
Other comprehensive income (loss)		(3,925)				(3,925)
Net loss		(547,795)					(547,795)
Ending balance (in shares) at Oct. 31, 2021	[1]		305,899,486
Ending balance at Oct. 31, 2021		$ 5,006,682	$ 30	[1]	6,797,354	(3,486)	(1,787,216)
Beginning balance (in shares) at Jul. 31, 2021		0
Beginning balance at Jul. 31, 2021		$ 0
Ending balance (in shares) at Oct. 31, 2021		0
Ending balance at Oct. 31, 2021		$ 0
Beginning balance (in shares) at Jul. 31, 2021			300,584,903
Beginning balance at Jul. 31, 2021		$ 4,964,965	$ 30		6,596,154	1,141	(1,632,360)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		4,222,037	4,222,037
Issuance of common stock upon exercise of stock options		$ 24,708			24,708
Issuance of common stock under employee stock purchase plan (in shares)			111,645
Issuance of common stock under employee stock purchase plan		25,829			25,829
Vesting of early exercised stock options and restricted common stock		191			191
Vesting of restricted stock units (in shares)			980,901
Stock-based compensation		150,472			150,472
Other comprehensive income (loss)		(4,627)				(4,627)
Net loss		(154,856)					(154,856)
Ending balance (in shares) at Oct. 31, 2021	[1]		305,899,486
Ending balance at Oct. 31, 2021		$ 5,006,682	$ 30	[1]	$ 6,797,354	$ (3,486)	$ (1,787,216)

[1] On March 1, 2021, all shares of the Company’s then-outstanding Class B common stock were automatically converted into the same number of shares of Class A common stock, pursuant to the terms of the Company’s amended and restated certificate of incorporation. No additional shares of Class B common stock will be issued following such conversion. See Note 11 for further details.