<SEC-DOCUMENT>0001447669-20-000211.txt : 20201105
<SEC-HEADER>0001447669-20-000211.hdr.sgml : 20201105
<ACCEPTANCE-DATETIME>20201105191436
ACCESSION NUMBER:		0001447669-20-000211
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201103
FILED AS OF DATE:		20201105
DATE AS OF CHANGE:		20201105

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Hu George
		CENTRAL INDEX KEY:			0001386396

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37806
		FILM NUMBER:		201292018

	MAIL ADDRESS:	
		STREET 1:		C/O SALESFORCE.COM
		STREET 2:		1 MARKET STREET, SUITE 300
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94105

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TWILIO INC
		CENTRAL INDEX KEY:			0001447669
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		375 BEALE ST
		STREET 2:		SUITE 300
		CITY:			San Francisco
		STATE:			CA
		ZIP:			94105
		BUSINESS PHONE:		650-270-2199

	MAIL ADDRESS:	
		STREET 1:		375 BEALE ST
		STREET 2:		SUITE 300
		CITY:			San Francisco
		STATE:			CA
		ZIP:			94105
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_160462166024331.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2020-11-03</periodOfReport>

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        <issuerName>TWILIO INC</issuerName>
        <issuerTradingSymbol>TWLO</issuerTradingSymbol>
    </issuer>

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            <rptOwnerCik>0001386396</rptOwnerCik>
            <rptOwnerName>Hu George</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TWILIO INC.</rptOwnerStreet1>
            <rptOwnerStreet2>101 SPEAR STREET, FIRST FLOOR</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94105</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Operating Officer</officerTitle>
            <otherText></otherText>
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                    <value>136692</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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                <value>Employee Stock Option (right to buy)</value>
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                <value>31.72</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-11-03</value>
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                    <value>18488</value>
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                    <value>31.72</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F7"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-02-27</value>
            </expirationDate>
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                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
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                    <value>18488.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                    <value>83930</value>
                </sharesOwnedFollowingTransaction>
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            </securityTitle>
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            <exerciseDate>
                <footnoteId id="F8"/>
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            <expirationDate>
                <value>2030-02-21</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>58559.0</value>
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                    <value>58559</value>
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        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
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                <value>33.01</value>
            </conversionOrExercisePrice>
            <exerciseDate>
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            <expirationDate>
                <value>2028-02-19</value>
            </expirationDate>
            <underlyingSecurity>
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                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
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            </securityTitle>
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            <expirationDate>
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            <underlyingSecurity>
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                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
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                <value>31.72</value>
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            <exerciseDate>
                <footnoteId id="F11"/>
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            <expirationDate>
                <value>2024-02-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
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                <underlyingSecurityShares>
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        <derivativeHolding>
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                <value>Employee Stock Option (right to buy)</value>
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            <expirationDate>
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                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
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                <sharesOwnedFollowingTransaction>
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                    <value>D</value>
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        <derivativeHolding>
            <securityTitle>
                <value>Employee Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>31.72</value>
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            <exerciseDate>
                <footnoteId id="F13"/>
            </exerciseDate>
            <expirationDate>
                <value>2024-02-27</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>185000.0</value>
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            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>185000</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
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    <footnotes>
        <footnote id="F1">A portion of these shares represent Restricted Stock Units (&quot;RSUs&quot;). Each RSU represents a contingent right to receive one share of Issuer's Class A common stock.</footnote>
        <footnote id="F2">The sales reported were effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person.</footnote>
        <footnote id="F3">The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $270.225 to $270.94 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or to the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.</footnote>
        <footnote id="F4">The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $271.34 to $272.33 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or to the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.</footnote>
        <footnote id="F5">The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $272.405 to $273.16 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or to the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.</footnote>
        <footnote id="F6">The reported price in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $273.41 to $274.26 per share, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or to the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.</footnote>
        <footnote id="F7">The shares subject to the stock option vest as follows: 25% of the stock option vested on February 28, 2018 and the remaining shares subject to the stock option shall vest in equal monthly installments over the following three years, subject to the Reporting Person's continued service to the Issuer through each vesting date.</footnote>
        <footnote id="F8">The shares subject to the stock option vest as follows: 33% of the stock option shall vest in equal quarterly installments between the first and second anniversaries of December 31, 2019, 33% of the stock option shall vest in equal quarterly installments between the second and third anniversaries of December 31, 2019 and 34% of the stock option shall vest in equal quarterly installments between the third and fourth anniversaries of December 31, 2019, subject to the Reporting Person's continued service to the Issuer through each vesting date.</footnote>
        <footnote id="F9">The shares subject to the stock option vest in 48 equal monthly installments, with the first installment on March 15, 2018, subject to the Reporting Person's continuous service to the Issuer through each vesting date.</footnote>
        <footnote id="F10">The shares subject to the stock option vest as follows: 50% of the stock option vested on March 31, 2018 and the remaining shares subject to the stock option shall vest in 24 equal monthly installments thereafter, subject to the Reporting Person's continued service to the Issuer through each vesting date.</footnote>
        <footnote id="F11">The shares subject to the stock option vest as follows: 50% of the stock option vested on June 30, 2019 and the remaining shares subject to the stock option shall vest in 24 equal monthly installments thereafter, subject to the Reporting Person's continued service to the Issuer through each vesting date.</footnote>
        <footnote id="F12">The shares subject to the stock option vest as follows: 33% of the stock option shall vest on December 31, 2020, 33% of the stock option shall vest on December 31, 2021 and 34% of the stock option shall vest on December 31, 2022, subject to the Reporting Person's continued service to the Issuer through each vesting date.</footnote>
        <footnote id="F13">The shares subject to the stock option vest as follows: 50% of the stock option vested on December 31, 2018 and the remaining shares subject to the stock option shall vest in 24 equal monthly installments thereafter, subject to the Reporting Person's continued service to the Issuer through each vesting date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Shanti Ariker as attorney in fact for Reporting Person</signatureName>
        <signatureDate>2020-11-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
