<?xml version="1.0" encoding="UTF-8"?><ns2:edgarSubmission xmlns:com="http://www.sec.gov/edgar/common" xmlns:ns2="http://www.sec.gov/edgar/ownership">
    <ns2:headerData>
        <ns2:submissionType>144</ns2:submissionType>
        <ns2:filerInfo>
            <ns2:filer>
                <ns2:filerCredentials>
                    <ns2:cik>0001641407</ns2:cik>
                    <ns2:ccc>XXXXXXXX</ns2:ccc>
                </ns2:filerCredentials>
            </ns2:filer>
            <ns2:liveTestFlag>LIVE</ns2:liveTestFlag>



        </ns2:filerInfo>
    </ns2:headerData>
    <ns2:formData>
        <ns2:issuerInfo>
            <ns2:issuerCik>0000935036</ns2:issuerCik>
            <ns2:issuerName>ACI Worldwide, Inc.</ns2:issuerName>
            <ns2:secFileNumber>000-25346</ns2:secFileNumber>
            <ns2:issuerAddress>
                <com:street1>3520 Kraft Road</com:street1>
                <com:street2>Suite 300</com:street2>
                <com:city>Naples</com:city>
                <com:stateOrCountry>FL</com:stateOrCountry>
                <com:zipCode>34105</com:zipCode>
            </ns2:issuerAddress>
            <ns2:issuerContactPhone>1-402-390-7600</ns2:issuerContactPhone>
            <ns2:nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Adalio T. Sanchez</ns2:nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
            <ns2:relationshipsToIssuer>
                <ns2:relationshipToIssuer>Officer</ns2:relationshipToIssuer>
            </ns2:relationshipsToIssuer>
        </ns2:issuerInfo>
        <ns2:securitiesInformation>
            <ns2:securitiesClassTitle>Common Shares</ns2:securitiesClassTitle>
            <ns2:brokerOrMarketmakerDetails>
                <ns2:name>Goldman Sachs &amp; Co. LLC</ns2:name>
                <ns2:address>
                    <com:street1>200 West Street</com:street1>
                    <com:city>New York</com:city>
                    <com:stateOrCountry>NY</com:stateOrCountry>
                    <com:zipCode>10282</com:zipCode>
                </ns2:address>
            </ns2:brokerOrMarketmakerDetails>
            <ns2:noOfUnitsSold>9750</ns2:noOfUnitsSold>
            <ns2:aggregateMarketValue>553507.5</ns2:aggregateMarketValue>
            <ns2:noOfUnitsOutstanding>104888642</ns2:noOfUnitsOutstanding>
            <ns2:approxSaleDate>11/13/2024</ns2:approxSaleDate>
            <ns2:securitiesExchangeName>NASD</ns2:securitiesExchangeName>
        </ns2:securitiesInformation>
        <ns2:securitiesToBeSold>
            <ns2:securitiesClassTitle>Common Shares</ns2:securitiesClassTitle>
            <ns2:acquiredDate>06/01/2021</ns2:acquiredDate>
            <ns2:natureOfAcquisitionTransaction>Acquired as compensation -- Restricted Stock Units</ns2:natureOfAcquisitionTransaction>
            <ns2:nameOfPersonfromWhomAcquired>Issuer</ns2:nameOfPersonfromWhomAcquired>
            <ns2:isGiftTransaction>N</ns2:isGiftTransaction>
            <ns2:amountOfSecuritiesAcquired>1200</ns2:amountOfSecuritiesAcquired>
            <ns2:paymentDate>06/01/2021</ns2:paymentDate>
            <ns2:natureOfPayment>Compensation</ns2:natureOfPayment>
        </ns2:securitiesToBeSold>
        <ns2:securitiesToBeSold>
            <ns2:securitiesClassTitle>Common Shares</ns2:securitiesClassTitle>
            <ns2:acquiredDate>06/09/2016</ns2:acquiredDate>
            <ns2:natureOfAcquisitionTransaction>Acquired as compensation -- Restricted Stock Units</ns2:natureOfAcquisitionTransaction>
            <ns2:nameOfPersonfromWhomAcquired>Issuer</ns2:nameOfPersonfromWhomAcquired>
            <ns2:isGiftTransaction>N</ns2:isGiftTransaction>
            <ns2:amountOfSecuritiesAcquired>8550</ns2:amountOfSecuritiesAcquired>
            <ns2:paymentDate>06/09/2016</ns2:paymentDate>
            <ns2:natureOfPayment>Compensation</ns2:natureOfPayment>
        </ns2:securitiesToBeSold>
        <ns2:nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</ns2:nothingToReportFlagOnSecuritiesSoldInPast3Months>
        <ns2:remarks>1,200 shares to be sold by Adalio Sanchez and 8,550 shares to be sold by Adalio Sanchez Irrevocable Trust.</ns2:remarks>
        <ns2:noticeSignature>
            <ns2:noticeDate>11/13/2024</ns2:noticeDate>
            <ns2:planAdoptionDates/>
            <ns2:signature>Goldman Sachs &amp; Co. LLC on behalf of Adalio T. Sanchez</ns2:signature>
        </ns2:noticeSignature>
    </ns2:formData>
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144
0001641407
XXXXXXXX
LIVE
0000935036
ACI Worldwide, Inc.
000-25346
3520 Kraft Road
Suite 300
Naples
FL
34105
1-402-390-7600
Adalio T. Sanchez
Officer
Common Shares
Goldman Sachs & Co. LLC
200 West Street
New York
NY
10282
9750
553507.5
104888642
11/13/2024
NASD
Common Shares
06/01/2021
Acquired as compensation -- Restricted Stock Units
Issuer
N
1200
06/01/2021
Compensation
Common Shares
06/09/2016
Acquired as compensation -- Restricted Stock Units
Issuer
N
8550
06/09/2016
Compensation
Y
1,200 shares to be sold by Adalio Sanchez and 8,550 shares to be sold by Adalio Sanchez Irrevocable Trust.
11/13/2024
Goldman Sachs & Co. LLC on behalf of Adalio T. Sanchez