content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <!-- Generated by Workiva -->
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001166976</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001158324</issuerCik>
        <issuerName>Cogent Communications Holdings, Inc.</issuerName>
        <secFileNumber>000-51829</secFileNumber>
        <issuerAddress>
          <com:street1>2450 N.  Street  N.W.</com:street1>
          <com:city>Washington</com:city>
          <com:stateOrCountry>DC</com:stateOrCountry>
          <com:zipCode>20037</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>202-295-4200</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>David Schaeffer</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Founder</relationshipToIssuer>
          <relationshipToIssuer>CEO</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>JP Morgan Securities LLC</name>
          <address>
            <com:street1>390 Madison Avenue</com:street1>
            <com:street2>6th Floor</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10017</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>45000</noOfUnitsSold>
        <aggregateMarketValue>3067650</aggregateMarketValue>
        <noOfUnitsOutstanding>48884279</noOfUnitsOutstanding>
        <approxSaleDate>09/07/2023</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>04/01/2013</acquiredDate>
        <natureOfAcquisitionTransaction>Stock grant</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>45000</amountOfSecuritiesAcquired>
        <paymentDate>04/01/2013</paymentDate>
        <natureOfPayment>Cash</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>David Schaeffer</name>
          <address>
            <com:street1>care of Issuer</com:street1>
            <com:street2>2450 N Street N.W.</com:street2>
            <com:city>Washington</com:city>
            <com:stateOrCountry>DC</com:stateOrCountry>
            <com:zipCode>20037</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>06/08/2023</saleDate>
        <amountOfSecuritiesSold>7001</amountOfSecuritiesSold>
        <grossProceeds>440878.25</grossProceeds>
      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>David Schaeffer</name>
          <address>
            <com:street1>care of Issuer</com:street1>
            <com:street2>2450 N Street N.W.</com:street2>
            <com:city>Washington</com:city>
            <com:stateOrCountry>DC</com:stateOrCountry>
            <com:zipCode>20037</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <saleDate>06/07/2023</saleDate>
        <amountOfSecuritiesSold>42334</amountOfSecuritiesSold>
        <grossProceeds>2637459</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>09/07/2023</noticeDate>
        <signature>/s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for David Schaeffer</signature>
      </noticeSignature>
    </formData>
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text: 144
  0001166976
  XXXXXXXX
  LIVE
  0001158324
  Cogent Communications Holdings, Inc.
  000-51829
  2450 N.  Street  N.W.
  Washington
  DC
  20037
  202-295-4200
  David Schaeffer
  Founder
  CEO
  Common
  JP Morgan Securities LLC
  390 Madison Avenue
  6th Floor
  New York
  NY
  10017
  45000
  3067650
  48884279
  09/07/2023
  NASDAQ
  Common
  04/01/2013
  Stock grant
  Issuer
  N
  45000
  04/01/2013
  Cash
  N
  David Schaeffer
  care of Issuer
  2450 N Street N.W.
  Washington
  DC
  20037
  Common
  06/08/2023
  7001
  440878.25
  David Schaeffer
  care of Issuer
  2450 N Street N.W.
  Washington
  DC
  20037
  Common
  06/07/2023
  42334
  2637459
  09/07/2023
  /s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for David Schaeffer