CONSOLIDATED STATEMENTS OF CASH FLOW - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Cash flows from operating activities:
Net income	$ 672,316	$ 25,305	$ 7,584
Adjustments to reconcile net income to net cash provided by operating activities:
Stock-based compensation expense	275,818	73,109	8,941
Amortization of deferred contract acquisition costs	104,306	37,101	20,839
Provision for accounts receivable allowances	32,007	6,370	1,953
Depreciation and amortization	28,857	16,449	7,008
Charitable donation of common stock	23,312		0
Non-cash operating lease cost	10,887	6,885	0
Other	3,822	(1,068)	37
Changes in operating assets and liabilities:
Accounts receivable	(219,039)	(64,715)	(41,040)
Prepaid expenses and other assets	(68,521)	(24,805)	(7,971)
Deferred contract acquisition costs	(307,068)	(72,714)	(45,769)
Accounts payable	3,481	(2,030)	832
Accrued expenses and other liabilities	251,654	51,179	27,407
Deferred revenue	665,724	106,286	71,511
Operating lease liabilities, net	(6,379)	(5,460)	0
Net cash provided by operating activities	1,471,177	151,892	51,332
Cash flows from investing activities:
Purchases of marketable securities	(2,056,470)	(800,228)	(78,016)
Maturities of marketable securities	580,795	343,554	68,747
Sales of marketable securities	36,897	0	0
Purchases of property and equipment	(79,972)	(38,084)	(28,432)
Cash paid for acquisition, net of cash acquired	(26,486)	0	0
Purchase of equity investment	(8,000)	(3,000)	0
Purchases of intangible assets	(5,843)	(141)	(2,018)
Purchase of convertible promissory note	(5,000)	0	0
Other	1,659	(1,569)	0
Net cash used in investing activities	(1,562,420)	(499,468)	(39,719)
Cash flows from financing activities:
Proceeds from follow-on public offering, net of underwriting discounts and commissions and other offering costs	1,979,206	0	0
Proceeds from issuance of common stock for employee stock purchase plan	38,433	15,482	0
Proceeds from exercise of stock options, net of repurchases	28,550	9,169	3,565
Proceeds from employee equity transactions to be remitted to employees and tax authorities, net	4,088	48,547	0
Proceeds from initial public offering and private placement, net of underwriting discounts and commissions and other offering costs	0	542,492	(939)
Proceeds from issuance of convertible promissory notes and derivatives	0	0	15,000
Principal payments on capital lease obligations	0	0
Principal payments on capital lease obligations			(92)
Net cash provided by financing activities	2,050,277	615,690	17,534
Net increase in cash, cash equivalents, and restricted cash	1,959,034	268,114	29,147
Cash, cash equivalents, and restricted cash—beginning of year	334,082	65,968	36,821
Cash, cash equivalents, and restricted cash—end of year	2,293,116	334,082	65,968
Supplemental disclosures of cash flow information
Cash paid for income taxes, net	3,181	1,070	214
Supplemental disclosures of non-cash investing and financing information
Purchase of equipment during the period included in accounts payable and accrued expenses	34,514	1,422	3,284
Vesting of early exercised stock options and restricted stock awards	558	725	277
Deferred offering costs, accrued but not paid	0	0	1,490
Reconciliation of cash, cash equivalents, and restricted cash within the consolidated balance sheets to the amounts shown in the consolidated statements of cash flows above:
Cash and cash equivalents	2,240,303	283,134	63,624
Total cash, cash equivalents, and restricted cash	2,293,116	65,968	36,821
Class B Common Stock
Cash flows from operating activities:
Net income	239,348	19,855	7,584
Supplemental disclosures of non-cash investing and financing information
Conversion of convertible preferred stock to Class B common stock upon initial public offering	0	159,552	0
Class A Common Stock
Cash flows from operating activities:
Net income	432,968	5,450	0
Supplemental disclosures of non-cash investing and financing information
Conversion of debt to Class A common stock	$ 0	$ 15,344	$ 0