<SEC-DOCUMENT>0001433195-18-000002.txt : 20180129
<SEC-HEADER>0001433195-18-000002.hdr.sgml : 20180129
<ACCEPTANCE-DATETIME>20180129203118
ACCESSION NUMBER:		0001433195-18-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20180126
FILED AS OF DATE:		20180129
DATE AS OF CHANGE:		20180129

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Randall Jason Robert
		CENTRAL INDEX KEY:			0001671594

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37468
		FILM NUMBER:		18557292

	MAIL ADDRESS:	
		STREET 1:		4942 LA GAMA WAY
		CITY:			SANTA BARBARA
		STATE:			CA
		ZIP:			93111

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			APPFOLIO INC
		CENTRAL INDEX KEY:			0001433195
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				260359894
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		50 CASTILIAN DRIVE
		CITY:			GOLETA
		STATE:			CA
		ZIP:			93117
		BUSINESS PHONE:		8053646093

	MAIL ADDRESS:	
		STREET 1:		50 CASTILIAN DRIVE
		CITY:			GOLETA
		STATE:			CA
		ZIP:			93117
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_151727586419942.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-01-26</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001433195</issuerCik>
        <issuerName>APPFOLIO INC</issuerName>
        <issuerTradingSymbol>APPF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001671594</rptOwnerCik>
            <rptOwnerName>Randall Jason Robert</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>50 CASTILIAN DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SANTA BARBARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93117</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </securityTitle>
            <transactionDate>
                <value>2018-01-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>25000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>43</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>47500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These shares were sold in a privately negotiated transaction with certain existing stockholders and did not involve any open market transaction.</footnote>
        <footnote id="F2">Each share of Class B Common Stock is convertible, at any time at the option of the holder, into one share of Class A Common Stock. In addition, each share of Class B Common Stock will convert automatically into one share of Class A Common Stock upon any transfer, except for any transfers by (i) a partnership or limited liability company prior to June 30, 2015, and (ii) a transfer to a &quot;qualified recipient,&quot; as defined in the Issuer's amended and restated certificate of incorporation.</footnote>
        <footnote id="F3">All of the outstanding shares of Class B Common Stock will convert automatically into shares of Class A Common Stock, on a one share-for-one share basis, on the date when the number of the Company's outstanding shares of Class B Common Stock represents less than 10% of the sum of its outstanding shares of Class A Common Stock and Class B Common Stock.</footnote>
        <footnote id="F4">The shares of Class B Common reported on the table above are held by the Jason R Randall &amp; Christina L Walman Revocable Trust Dated 06/01/17 of which Mr. Randall is a Trustee.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Ida Kane, as Attorney-in-Fact for Jason Robert Randall</signatureName>
        <signatureDate>2018-01-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
