CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	(Accumulated Deficit) Retained Earnings
Beginning balance (in shares) at Jan. 31, 2018	152,665,804
Beginning balance at Jan. 31, 2018	$ 159,552
Ending balance (in shares) at Jan. 31, 2019	152,665,804
Ending balance at Jan. 31, 2019	$ 159,552
Beginning balance (in shares) at Jan. 31, 2018		82,609,638
Beginning balance at Jan. 31, 2018	(26,671)	$ 80	$ 6,517	$ (531)	$ (32,737)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		7,717,797
Issuance of common stock upon exercise of stock options	2,311	$ 9	2,302
Stock-based compensation expense	8,941		8,941
Other comprehensive income	396			396
Net income	7,584				7,584
Ending balance (in shares) at Jan. 31, 2019		90,327,435
Ending balance at Jan. 31, 2019	(7,439)	$ 89	17,760	(135)	(25,153)
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock to common stock upon initial public offering	$ (159,552)
Ending balance (in shares) at Jan. 31, 2020	0
Ending balance at Jan. 31, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of convertible preferred stock to common stock upon initial public offering (in shares)		152,665,804
Conversion of convertible preferred stock to common stock upon initial public offering	159,552	$ 153	159,399
Conversion of convertible promissory notes and accrued interest to common stock upon initial public offering (in shares)		426,223
Conversion of convertible promissory notes and accrued interest to common stock upon initial public offering	15,344
Issuance of common stock, net of underwriting discounts and commissions and other offering costs (in shares)		15,819,646
Issuance of common stock, net of underwriting discounts and commissions and other offering costs	541,499	$ 16	541,483
Issuance of common stock upon exercise of stock options, net of repurchases and release of restricted stock units (in shares)		18,501,767
Issuance of common stock upon exercise of stock options, net of repurchases and release of restricted stock units	$ 9,771	$ 19	9,752
Issuance of common stock reserved for charitable donation (in shares)	500,000
Issuance of common stock for employee stock purchase plan (in shares)		490,268
Issuance of common stock for employee stock purchase plan	$ 15,482		15,482
Stock-based compensation expense	73,485		73,485
Other comprehensive income	944			944
Net income	25,305				25,305
Ending balance (in shares) at Jan. 31, 2020		278,731,143
Ending balance at Jan. 31, 2020	$ 833,943	$ 277	832,705	809	152
Increase (Decrease) in Temporary Equity [Roll Forward]
Conversion of convertible preferred stock to common stock upon initial public offering (in shares)	(152,665,804)
Ending balance (in shares) at Jan. 31, 2021	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	7,378,477	7,378,477
Issuance of common stock upon exercise of stock options	$ 29,107	$ 7	29,100
Issuance of common stock, net of underwriting discounts and commissions and other offering costs (in shares)		5,882,353
Issuance of common stock, net of underwriting discounts and commissions and other offering costs	1,979,544	$ 6	1,979,538
Issuance of common stock upon release of restricted stock units (in shares)		633,697
Issuance of common stock upon release of restricted stock units	1	$ 1
Issuance of common stock reserved for charitable donations	23,312		23,312
Issuance of common stock for employee stock purchase plan (in shares)		923,553
Issuance of common stock for employee stock purchase plan	38,433	$ 1	38,432
Stock-based compensation expense	284,081		284,081
Other comprehensive income	30			30
Net income	672,316				672,316
Ending balance (in shares) at Jan. 31, 2021		293,549,223
Ending balance at Jan. 31, 2021	$ 3,860,767	$ 292	$ 3,187,168	$ 839	$ 672,468