CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK, REDEEMABLE CONVERTIBLE CLASS A-1 COMMON STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Initial Public Offering and Private Placements	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Common Stock Initial Public Offering and Private Placements	Additional Paid-In Capital	Additional Paid-In Capital Initial Public Offering and Private Placements	Additional Paid-In Capital Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	Accumulated Deficit Cumulative Effect, Period of Adoption, Adjustment	Redeemable Convertible Preferred Stock	Series G Preferred Stock	Series H Preferred Stock	Redeemable Convertible A-1 Common Stock
Beginning Balance, shares (in shares) at Apr. 30, 2018												31,582,000			6,667,000
Beginning Balance, Amount at Apr. 30, 2018												$ 248,471			$ 18,800
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Preferred Stock, net of issuance costs (in shares)													2,610,000
Issuance of Preferred Stock, net of issuance costs													$ 51,494
Ending Balance, shares (in shares) at Apr. 30, 2019												34,192,000			6,667,000
Ending Balance, Amount at Apr. 30, 2019												$ 299,965			$ 18,800
Beginning Balance, shares (in shares) at Apr. 30, 2018				18,568,000
Beginning Balance, Amount at Apr. 30, 2018	$ (139,830)		$ 0	$ 19		$ 50,999		$ 66	$ (1)	$ (190,847)	$ (66)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock upon exercise of stock options (in shares)				1,489,000
Issuance of Class A common stock upon exercise of stock options	1,839			$ 1		1,838
Vesting of early exercised Class A common stock options	1,561					1,561
Stock-based compensation expense	4,267					4,267
Other comprehensive income (loss)	75								75
Net loss	(33,346)									(33,346)
Ending Balance, shares (in shares) at Apr. 30, 2019				20,057,000
Ending Balance, Amount at Apr. 30, 2019	(165,434)			$ 20		58,731			74	(224,259)
Increase (Decrease) in Temporary Equity [Roll Forward]
Issuance of Preferred Stock, net of issuance costs (in shares)													1,283,000	1,654,000
Issuance of Preferred Stock, net of issuance costs													$ 25,406	$ 49,836
Ending Balance, shares (in shares) at Apr. 30, 2020												37,128,768	3,893,701	1,653,928	6,666,665
Ending Balance, Amount at Apr. 30, 2020												$ 375,207	$ 76,900	$ 49,836	$ 18,800
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)				9,530,000
Issuance of common stock	$ 44,027			$ 10		44,017
Issuance of Class A common stock upon exercise of stock options (in shares)	1,809,000			1,787,000
Issuance of Class A common stock upon exercise of stock options	$ 2,321			$ 2		2,319
Vesting of early exercised Class A common stock options	655					655
Tender offer repurchases (in shares)				(164,000)
Tender offer repurchases	(3,548)			$ (1)		(3,547)
Stock-based compensation expense	8,310					8,310
Other comprehensive income (loss)	350								350
Net loss	(69,378)									(69,378)
Ending Balance, shares (in shares) at Apr. 30, 2020				31,210,000
Ending Balance, Amount at Apr. 30, 2020	(182,697)			$ 31		110,485			424	(293,637)
Increase (Decrease) in Temporary Equity [Roll Forward]
Repayment of Shareholder Loan												$ 24,546
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)												(37,129,000)			(6,667,000)
Conversion of redeemable convertible preferred stock to common stock upon initial public offering												$ (399,753)			$ (18,800)
Ending Balance, shares (in shares) at Apr. 30, 2021												0			0
Ending Balance, Amount at Apr. 30, 2021												$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repayment of Shareholder Loan	1,457					1,457
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)				43,796,000
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	$ 418,553			$ 44		418,509
Issuance of common stock (in shares)					21,396,000
Issuance of common stock		$ 844,575			$ 21		$ 844,554
Issuance of Class A common stock upon exercise of stock options (in shares)	5,799,000			5,765,000
Issuance of Class A common stock upon exercise of stock options	$ 10,717			$ 6		10,711
Vesting of early exercised Class A common stock options	2,869					2,869
Stock-based compensation expense	21,740					21,740
Other comprehensive income (loss)		$ (343)							(343)
Net loss	$ (55,696)									(55,696)
Ending Balance, shares (in shares) at Apr. 30, 2021	3,499,992			102,167,000
Ending Balance, Amount at Apr. 30, 2021	$ 1,061,175			$ 102		$ 1,410,325			$ 81	$ (349,333)