CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK, REDEEMABLE CONVERTIBLE CLASS A-1 COMMON STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Redeemable Convertible Preferred Stock	Redeemable Convertible A-1 Common Stock
Beginning Balance, shares (in shares) at Apr. 30, 2020						37,129,000	6,667,000
Beginning Balance, Amount at Apr. 30, 2020						$ 375,207	$ 18,800
Ending Balance, shares (in shares) at Jul. 31, 2020						37,129,000	6,667,000
Ending Balance, Amount at Jul. 31, 2020						$ 375,207	$ 18,800
Beginning Balance, shares (in shares) at Apr. 30, 2020		31,210,000
Beginning Balance, Amount at Apr. 30, 2020	$ (182,697)	$ 31	$ 110,485	$ 424	$ (293,637)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock upon exercise of stock options (in shares)		132,000
Issuance of Class A common stock upon exercise of stock options	335		335
Vesting of early exercised Class A common stock options	218		218
Stock-based compensation expense	2,480		2,480
Other comprehensive income (loss)	(167)			(167)
Net (loss) income	150				150
Ending Balance, shares (in shares) at Jul. 31, 2020		31,342,000
Ending Balance, Amount at Jul. 31, 2020	(179,681)	$ 31	113,518	257	(293,487)
Beginning Balance, shares (in shares) at Apr. 30, 2021						0	0
Beginning Balance, Amount at Apr. 30, 2021						$ 0	$ 0
Ending Balance, shares (in shares) at Jul. 31, 2021						0	0
Ending Balance, Amount at Jul. 31, 2021						$ 0	$ 0
Beginning Balance, shares (in shares) at Apr. 30, 2021		102,167,000
Beginning Balance, Amount at Apr. 30, 2021	1,061,175	$ 102	1,410,325	81	(349,333)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock (in shares)		1,693,000
Issuance of Class A common stock	$ 5,002	$ 2	5,000
Issuance of Class A common stock upon exercise of stock options (in shares)	1,693,000
Vesting of early exercised Class A common stock options	$ 1,059		1,059
Vesting of restricted stock units (in shares)		8,000
Stock-based compensation expense	13,912		13,912
Other comprehensive income (loss)	106			106
Net (loss) income	(37,459)				(37,459)
Ending Balance, shares (in shares) at Jul. 31, 2021		103,868,000
Ending Balance, Amount at Jul. 31, 2021	$ 1,043,795	$ 104	$ 1,430,296	$ 187	$ (386,792)