Cover - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Feb. 02, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-37468
Entity Registrant Name	AppFolio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-0359894
Entity Address, Address Line One	70 Castilian Drive
Entity Address, City or Town	Santa Barbara,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	93117
City Area Code	805
Local Phone Number	364-6093
Title of each class	Class A common stock, par value $0.0001 per share
Trading Symbol	APPF
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 2,136
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement for the 2023 Annual Meeting of Stockholders (the “Proxy Statement”), to be filed with the Securities and Exchange Commission (the “SEC”) pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K (this “Annual Report”), are incorporated by reference in Part III, Items 10-14 of this Annual Report. Except for the portions of the Proxy Statement specifically incorporated by reference in this Annual Report, the Proxy Statement shall not be deemed to be filed as part hereof.
Entity Central Index Key	0001433195
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false
Class A common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		20,649,685
Class B common stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		14,746,432