<SEC-DOCUMENT>0001213191-15-000006.txt : 20151008
<SEC-HEADER>0001213191-15-000006.hdr.sgml : 20151008
<ACCEPTANCE-DATETIME>20151008213207
ACCESSION NUMBER:		0001213191-15-000006
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20151006
FILED AS OF DATE:		20151008
DATE AS OF CHANGE:		20151008

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			APPFOLIO INC
		CENTRAL INDEX KEY:			0001433195
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Investment Group of Santa Barbara, LLC
		CENTRAL INDEX KEY:			0001645662
		STATE OF INCORPORATION:			CA
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37468
		FILM NUMBER:		151151871

	BUSINESS ADDRESS:	
		STREET 1:		1485 EAST VALLEY ROAD, SUITE H
		CITY:			SANTA BARBARA
		STATE:			CA
		ZIP:			93108
		BUSINESS PHONE:		805-690-6116

	MAIL ADDRESS:	
		STREET 1:		P.O. BOX 5609
		CITY:			SANTA BARBARA
		STATE:			CA
		ZIP:			93150

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RAUTH WILLIAM R III
		CENTRAL INDEX KEY:			0001213191

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37468
		FILM NUMBER:		151151872

	MAIL ADDRESS:	
		STREET 1:		PO BOX 5609
		CITY:			SANTA BARBARA
		STATE:			CA
		ZIP:			93150
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_144435431715751.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-10-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001213191</rptOwnerCik>
            <rptOwnerName>RAUTH WILLIAM R III</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O IGSB, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1485 E VALLEY ROAD, SUITE H</rptOwnerStreet2>
            <rptOwnerCity>SANTA BARBARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93108</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001645662</rptOwnerCik>
            <rptOwnerName>Investment Group of Santa Barbara, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O IGSB, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1485 E VALLEY ROAD, SUITE H</rptOwnerStreet2>
            <rptOwnerCity>SANTA BARBARA</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>93108</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-10-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>242424</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>16.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>242424.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>993627</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F3"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By IGSB Internal Venture Fund III</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The shares of Class B Common Stock do not have an expiration date.  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, shares of Class B Common Stock that are transferred by the Reporting Person will convert automatically, on a one share-for-one share basis, into shares of Class A Common Stock, except for (i) any transfers to any person that is, and prior to June 30, 2015 was, a member of the Reporting Person, and (ii) any transfer to a &quot;qualified recipient&quot; as defined in the Company's Amended and Restated Certificate of Incorporation.</footnote>
        <footnote id="F2">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="F3">These shares of Class B Common Stock are owned by IGSB Internal Venture Fund III LLC, a private investment fund managed by Investment Group of Santa Barbara LLC (IGSB).  Mr. Rauth is one of three members of IGSB and all decisions regarding the voting and disposition of these shares require the unanimous approval of all three members.  As a result, Mr. Rauth may be deemed to share voting and dispositive power over these shares with IGSB and its other two members.  However, Mr. Rauth disclaims beneficial ownership of these shares, except to the extent of any pecuniary interest he may have therein.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>William R. Rauth, III
/s/ Kimberly Shea, attorney-in-fact for William R. Rauth, III</signatureName>
        <signatureDate>2015-10-08</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Investment Group of Santa Barbara, LLC, A California limited liability company

By:  Timothy K. Bliss, Member &amp; Vice President

By: /s/ Kimberly Shea, attorney-in-fact for Timothy K. Bliss, Member and Vice President</signatureName>
        <signatureDate>2015-10-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
