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            <ccc>XXXXXXXX</ccc>
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        <liveTestFlag>LIVE</liveTestFlag>
  
  
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      <issuerInfo>
        <issuerCik>0000704532</issuerCik>
        <issuerName>ONTO INNOVATION INC.</issuerName>
        <secFileNumber>001-39110</secFileNumber>
        <issuerAddress>
          <com:street1>16 JONSPIN ROAD</com:street1>
          <com:city>WILMINGTON</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>01887</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>9782536200</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Plisinski Michael P</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>245 Summer Street</com:street1>
            <com:city>Boston</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02110</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>31000</noOfUnitsSold>
        <aggregateMarketValue>3498413.90</aggregateMarketValue>
        <noOfUnitsOutstanding>49065801</noOfUnitsOutstanding>
        <approxSaleDate>08/21/2023</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/06/2022</acquiredDate>
        <natureOfAcquisitionTransaction>RSU</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Onto Innovation Inc.</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>3589</amountOfSecuritiesAcquired>
        <paymentDate>02/06/2022</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/07/2022</acquiredDate>
        <natureOfAcquisitionTransaction>RSU</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Onto Innovation Inc.</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>5749</amountOfSecuritiesAcquired>
        <paymentDate>02/07/2022</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/08/2022</acquiredDate>
        <natureOfAcquisitionTransaction>RSU</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Onto Innovation Inc.</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>4575</amountOfSecuritiesAcquired>
        <paymentDate>02/08/2022</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/02/2022</acquiredDate>
        <natureOfAcquisitionTransaction>PSU</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Onto Innovation Inc.</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>17087</amountOfSecuritiesAcquired>
        <paymentDate>02/02/2022</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>08/21/2023</noticeDate>
        <planAdoptionDates>
          <planAdoptionDate>05/18/2023</planAdoptionDate>
        </planAdoptionDates>
        <signature>/s/ Myra King, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Michael P. Plisinski</signature>
      </noticeSignature>
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text: 144
  0001325550
  XXXXXXXX
  LIVE
  0000704532
  ONTO INNOVATION INC.
  001-39110
  16 JONSPIN ROAD
  WILMINGTON
  MA
  01887
  9782536200
  Plisinski Michael P
  Officer
  Common Stock
  Fidelity Brokerage Services LLC
  245 Summer Street
  Boston
  MA
  02110
  31000
  3498413.90
  49065801
  08/21/2023
  NYSE
  Common Stock
  02/06/2022
  RSU
  Onto Innovation Inc.
  N
  3589
  02/06/2022
  N/A
  Common Stock
  02/07/2022
  RSU
  Onto Innovation Inc.
  N
  5749
  02/07/2022
  N/A
  Common Stock
  02/08/2022
  RSU
  Onto Innovation Inc.
  N
  4575
  02/08/2022
  N/A
  Common Stock
  02/02/2022
  PSU
  Onto Innovation Inc.
  N
  17087
  02/02/2022
  N/A
  Y
  08/21/2023
  05/18/2023
  /s/ Myra King, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for Michael P. Plisinski