CONDENSED 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	Common Stock	Common Stock Initial Public Offering and Private Placements	Additional Paid-In Capital	Additional Paid-In Capital Initial Public Offering and Private Placements	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit	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, 2019									34,192,000			6,667,000
Beginning Balance, Amount at Apr. 30, 2019									$ 299,965			$ 18,800
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 Jan. 31, 2020									37,129,000			6,667,000
Ending Balance, Amount at Jan. 31, 2020									$ 375,207			$ 18,800
Beginning Balance, shares (in shares) at Apr. 30, 2019			20,057,000
Beginning Balance, Amount at Apr. 30, 2019	$ (165,434)		$ 20		$ 58,731		$ 74	$ (224,259)
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)			1,630,000
Issuance of Class A common stock upon exercise of stock options	2,015		$ 1		2,014
Vesting of early exercised Class A common stock options	427				427
Tender offer repurchases (in shares)			(164,000)
Tender offer repurchases	(3,548)		$ (1)		(3,547)
Stock-based compensation expense	5,424				5,424
Other comprehensive income (loss)	136						136
Net loss	(38,944)							(38,944)
Ending Balance, shares (in shares) at Jan. 31, 2020			31,053,000
Ending Balance, Amount at Jan. 31, 2020	(155,897)		$ 30		107,066		210	(263,203)
Beginning Balance, shares (in shares) at Apr. 30, 2019									34,192,000			6,667,000
Beginning Balance, Amount at Apr. 30, 2019									$ 299,965			$ 18,800
Ending Balance, shares (in shares) at Apr. 30, 2020									37,128,768			6,666,665
Ending Balance, Amount at Apr. 30, 2020									$ 375,207			$ 18,800
Beginning Balance, shares (in shares) at Apr. 30, 2019			20,057,000
Beginning Balance, Amount at Apr. 30, 2019	(165,434)		$ 20		58,731		74	(224,259)
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)
Beginning Balance, shares (in shares) at Oct. 31, 2019									37,129,000			6,667,000
Beginning Balance, Amount at Oct. 31, 2019									$ 375,207			$ 18,800
Ending Balance, shares (in shares) at Jan. 31, 2020									37,129,000			6,667,000
Ending Balance, Amount at Jan. 31, 2020									$ 375,207			$ 18,800
Beginning Balance, shares (in shares) at Oct. 31, 2019			30,779,000
Beginning Balance, Amount at Oct. 31, 2019	(148,833)		$ 30		104,403		141	(253,407)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)			274,000
Issuance of common stock	446				446
Vesting of early exercised Class A common stock options	156				156
Stock-based compensation expense	2,061				2,061
Other comprehensive income (loss)	69						69
Net loss	(9,796)							(9,796)
Ending Balance, shares (in shares) at Jan. 31, 2020			31,053,000
Ending Balance, Amount at Jan. 31, 2020	(155,897)		$ 30		107,066		210	(263,203)
Beginning Balance, shares (in shares) at Apr. 30, 2020									37,128,768			6,666,665
Beginning Balance, Amount at Apr. 30, 2020									$ 375,207			$ 18,800
Increase (Decrease) in Temporary Equity [Roll Forward]
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)
Repayment of shareholder loan									$ 24,546
Ending Balance, shares (in shares) at Jan. 31, 2021									0			0
Ending Balance, Amount at Jan. 31, 2021									$ 0			$ 0
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]
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
Repayment of shareholder loan	$ 1,457				1,457
Issuance of common stock (in shares)				21,396,000
Issuance of common stock		$ 844,646		$ 21		$ 844,625
Issuance of Class A common stock upon exercise of stock options (in shares)	4,563,000		4,530,000
Issuance of Class A common stock upon exercise of stock options	$ 7,867		$ 5		7,862
Vesting of early exercised Class A common stock options	2,073				2,073
Stock-based compensation expense	14,270				14,270
Other comprehensive income (loss)	(411)						(411)
Net loss	$ (31,646)							(31,646)
Ending Balance, shares (in shares) at Jan. 31, 2021	3,499,992		100,932,000
Ending Balance, Amount at Jan. 31, 2021	$ 1,074,112		$ 101		1,399,281		13	(325,283)
Beginning Balance, shares (in shares) at Oct. 31, 2020									37,129,000			6,667,000
Beginning Balance, Amount at Oct. 31, 2020									$ 399,753			$ 18,800
Increase (Decrease) in Temporary Equity [Roll Forward]
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 Jan. 31, 2021									0			0
Ending Balance, Amount at Jan. 31, 2021									$ 0			$ 0
Beginning Balance, shares (in shares) at Oct. 31, 2020			32,981,000
Beginning Balance, Amount at Oct. 31, 2020	(184,327)		$ 33		124,009		62	(308,431)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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		$ 844,646		$ 21		$ 844,625
Issuance of Class A common stock upon exercise of stock options (in shares)			2,759,000
Issuance of Class A common stock upon exercise of stock options	4,803		$ 3		4,800
Vesting of early exercised Class A common stock options	749				749
Stock-based compensation expense	6,589				6,589
Other comprehensive income (loss)	(49)						(49)
Net loss	$ (16,852)							(16,852)
Ending Balance, shares (in shares) at Jan. 31, 2021	3,499,992		100,932,000
Ending Balance, Amount at Jan. 31, 2021	$ 1,074,112		$ 101		$ 1,399,281		$ 13	$ (325,283)