<SEC-DOCUMENT>0001209191-20-056218.txt : 20201029
<SEC-HEADER>0001209191-20-056218.hdr.sgml : 20201029
<ACCEPTANCE-DATETIME>20201029161030
ACCESSION NUMBER:		0001209191-20-056218
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20201027
FILED AS OF DATE:		20201029
DATE AS OF CHANGE:		20201029

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Thakar Sumedh S
		CENTRAL INDEX KEY:			0001558242

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35662
		FILM NUMBER:		201272743

	MAIL ADDRESS:	
		STREET 1:		C/O QUALYS, INC.
		STREET 2:		1600 BRIDGE PARKWAY
		CITY:			REDWOOD SHORES
		STATE:			CA
		ZIP:			94065

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			QUALYS, INC.
		CENTRAL INDEX KEY:			0001107843
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		IRS NUMBER:				770534145
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		919 E. HILLSDALE BLVD.
		CITY:			FOSTER CITY
		STATE:			CA
		ZIP:			94404
		BUSINESS PHONE:		650-801-6100

	MAIL ADDRESS:	
		STREET 1:		919 E. HILLSDALE BLVD.
		CITY:			FOSTER CITY
		STATE:			CA
		ZIP:			94404

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	QUALYS INC
		DATE OF NAME CHANGE:	20000225
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc4.xml
<DESCRIPTION>FORM 4 SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-10-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001107843</issuerCik>
        <issuerName>QUALYS, INC.</issuerName>
        <issuerTradingSymbol>QLYS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001558242</rptOwnerCik>
            <rptOwnerName>Thakar Sumedh S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O QUALYS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>919 E. HILLSDALE BLVD.</rptOwnerStreet2>
            <rptOwnerCity>FOSTER CITY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94404</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Pres. &amp; Chief Product Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-10-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>81079</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>240075</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The reported securities represent restricted stock units which vest quarterly in equal installments over four years after November 1, 2020, subject to the Reporting Person's continued service through each vesting date.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Bruce Posey by power of attorney for Sumedh S. Thakar</signatureName>
        <signatureDate>2020-10-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
