Net Loss Per Share Attributable to Common Stockholders - Anti-Dilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2020
Class A Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	111,527	359,295	345,167
Class A Common Stock | Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	68,015	288,979	271,734
Class A Common Stock | Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	23,237	31,074	20,479
Class A Common Stock | Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	18,424	37,814	52,954
Class A Common Stock | Shares subject to repurchase from RSAs and early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	1,539	1,428	0
Class A Common Stock | Shares issuable under 2021 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	312	0	0
Class B Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	0	0	0
Class B Common Stock | Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	0	0	0
Class B Common Stock | Unvested RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	0	0	0
Class B Common Stock | Outstanding stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	0	0	0
Class B Common Stock | Shares subject to repurchase from RSAs and early exercised stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	0	0	0
Class B Common Stock | Shares issuable under 2021 ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total weighted-average anti-dilutive common stock equivalents	0	0	0