content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
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  <filerInfo>
  <filer>
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  <cik>0001720314</cik>
  <ccc>XXXXXXXX</ccc>
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  </filer>
  <liveTestFlag>LIVE</liveTestFlag>
  </filerInfo>
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  <formData>
  <issuerInfo>
  <issuerCik>0001701732</issuerCik>
  <issuerName>Altair Engineering Inc.	</issuerName>
  <secFileNumber>001-38263</secFileNumber>
  <issuerAddress>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. BIG BEAVER ROAD</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </issuerAddress>
  <issuerContactPhone>248-614-2400</issuerContactPhone>
  <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Scapa James Ralph</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
  <relationshipsToIssuer>
  <relationshipToIssuer>Owner</relationshipToIssuer>
  <relationshipToIssuer>Officer</relationshipToIssuer>
  <relationshipToIssuer>Director</relationshipToIssuer>
  </relationshipsToIssuer>
  </issuerInfo>
  <securitiesInformation>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <brokerOrMarketmakerDetails>
  <name>Morgan Stanley Smith Barney LLC</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">Harborside 2</street1>
  <street2 xmlns="http://www.sec.gov/edgar/common">200 Hudson Street, Suite 501</street2>
  <city xmlns="http://www.sec.gov/edgar/common">Jersey City</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">NJ</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">07311</zipCode>
  </address>
  </brokerOrMarketmakerDetails>
  <noOfUnitsSold>5560</noOfUnitsSold>
  <aggregateMarketValue>469117.16</aggregateMarketValue>
  <noOfUnitsOutstanding>56948286</noOfUnitsOutstanding>
  <approxSaleDate>05/08/2024</approxSaleDate>
  <securitiesExchangeName>NASDAQ</securitiesExchangeName>
  </securitiesInformation>
  <securitiesInformation>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <brokerOrMarketmakerDetails>
  <name>Morgan Stanley Smith Barney LLC</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">Harborside 2</street1>
  <street2 xmlns="http://www.sec.gov/edgar/common">200 Hudson Street, Suite 501</street2>
  <city xmlns="http://www.sec.gov/edgar/common">Jersey City</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">NJ</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">07311</zipCode>
  </address>
  </brokerOrMarketmakerDetails>
  <noOfUnitsSold>9</noOfUnitsSold>
  <aggregateMarketValue>759.42</aggregateMarketValue>
  <noOfUnitsOutstanding>56948286</noOfUnitsOutstanding>
  <approxSaleDate>05/08/2024</approxSaleDate>
  <securitiesExchangeName>NASDAQ</securitiesExchangeName>
  </securitiesInformation>
  <securitiesToBeSold>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <acquiredDate>05/07/2024</acquiredDate>
  <natureOfAcquisitionTransaction>Class A Common Stock Restricted Stock Unit Vesting</natureOfAcquisitionTransaction>
  <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
  <isGiftTransaction>N</isGiftTransaction>
  <amountOfSecuritiesAcquired>10750</amountOfSecuritiesAcquired>
  <paymentDate>05/07/2024</paymentDate>
  <natureOfPayment>N/A</natureOfPayment>
  </securitiesToBeSold>
  <securitiesToBeSold>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <acquiredDate>05/07/2024</acquiredDate>
  <natureOfAcquisitionTransaction>Class A Common Stock Restricted Stock Unit Vesting</natureOfAcquisitionTransaction>
  <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
  <isGiftTransaction>N</isGiftTransaction>
  <amountOfSecuritiesAcquired>21</amountOfSecuritiesAcquired>
  <paymentDate>05/07/2024</paymentDate>
  <natureOfPayment>N/A</natureOfPayment>
  </securitiesToBeSold>
  <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>James Scapa Declaration of Trust C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>02/16/2024</saleDate>
  <amountOfSecuritiesSold>5000</amountOfSecuritiesSold>
  <grossProceeds>455343.67</grossProceeds>
  </securitiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>JRS Investments LLC C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>02/16/2024</saleDate>
  <amountOfSecuritiesSold>5000</amountOfSecuritiesSold>
  <grossProceeds>455344.30</grossProceeds>
  </securitiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>James Ralph Scapa</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>03/04/2024</saleDate>
  <amountOfSecuritiesSold>3300</amountOfSecuritiesSold>
  <grossProceeds>281556.00</grossProceeds>
  </securitiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>James Ralph Scapa</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>03/13/2024</saleDate>
  <amountOfSecuritiesSold>1686</amountOfSecuritiesSold>
  <grossProceeds>137677.82</grossProceeds>
  </securitiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>Sally Scapa</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>03/13/2024</saleDate>
  <amountOfSecuritiesSold>93</amountOfSecuritiesSold>
  <grossProceeds>7594.38</grossProceeds>
  </securitiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>James Scapa Declaration of Trust C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>03/18/2024</saleDate>
  <amountOfSecuritiesSold>5000</amountOfSecuritiesSold>
  <grossProceeds>403711.99</grossProceeds>
  </securitiesSoldInPast3Months>
  <securitiesSoldInPast3Months>
  <sellerDetails>
  <name>JRS Investments LLC C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083</name>
  <address>
  <street1 xmlns="http://www.sec.gov/edgar/common">1820 E. Big Beaver Rd.</street1>
  <city xmlns="http://www.sec.gov/edgar/common">Troy</city>
  <stateOrCountry xmlns="http://www.sec.gov/edgar/common">MI</stateOrCountry>
  <zipCode xmlns="http://www.sec.gov/edgar/common">48083</zipCode>
  </address>
  </sellerDetails>
  <securitiesClassTitle>Class A Common Stock</securitiesClassTitle>
  <saleDate>03/18/2024</saleDate>
  <amountOfSecuritiesSold>5000</amountOfSecuritiesSold>
  <grossProceeds>403711.99</grossProceeds>
  </securitiesSoldInPast3Months>
  <remarks>Represents registered Class A common stock sold pursuant to the Issuer's 2017 Equity Incentive Plan for sell-to-cover transactions for tax withholding obligations resulting from the vesting of Class A common stock restricted stock units of both the filer and the filer's wife. Such sales were previously reported on a Form 4.</remarks>
  <noticeSignature>
  <noticeDate>05/20/2024</noticeDate>
  <signature>James Ralph Scapa</signature>
  </noticeSignature>
  </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 9228}]
text: 144
  0001720314
  XXXXXXXX
  LIVE
  0001701732
  Altair Engineering Inc.
  001-38263
  1820 E. BIG BEAVER ROAD
  Troy
  MI
  48083
  248-614-2400
  Scapa James Ralph
  Owner
  Officer
  Director
  Class A Common Stock
  Morgan Stanley Smith Barney LLC
  Harborside 2
  200 Hudson Street, Suite 501
  Jersey City
  NJ
  07311
  5560
  469117.16
  56948286
  05/08/2024
  NASDAQ
  Class A Common Stock
  Morgan Stanley Smith Barney LLC
  Harborside 2
  200 Hudson Street, Suite 501
  Jersey City
  NJ
  07311
  9
  759.42
  56948286
  05/08/2024
  NASDAQ
  Class A Common Stock
  05/07/2024
  Class A Common Stock Restricted Stock Unit Vesting
  Issuer
  N
  10750
  05/07/2024
  N/A
  Class A Common Stock
  05/07/2024
  Class A Common Stock Restricted Stock Unit Vesting
  Issuer
  N
  21
  05/07/2024
  N/A
  N
  James Scapa Declaration of Trust C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  02/16/2024
  5000
  455343.67
  JRS Investments LLC C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  02/16/2024
  5000
  455344.30
  James Ralph Scapa
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  03/04/2024
  3300
  281556.00
  James Ralph Scapa
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  03/13/2024
  1686
  137677.82
  Sally Scapa
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  03/13/2024
  93
  7594.38
  James Scapa Declaration of Trust C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  03/18/2024
  5000
  403711.99
  JRS Investments LLC C/o Altair Engineering, Inc. 1820 E. Big Beaver Road Troy MI 48083
  1820 E. Big Beaver Rd.
  Troy
  MI
  48083
  Class A Common Stock
  03/18/2024
  5000
  403711.99
  Represents registered Class A common stock sold pursuant to the Issuer's 2017 Equity Incentive Plan for sell-to-cover transactions for tax withholding obligations resulting from the vesting of Class A common stock restricted stock units of both the filer and the filer's wife. Such sales were previously reported on a Form 4.
  05/20/2024
  James Ralph Scapa