<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:5d82b6e1-3a51-46ed-975a-6ad1a5885d42,g:20352edf-f3df-4351-9e86-e306d67e1910-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:qlys="http://www.qualys.com/20241231" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types1="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.qualys.com/20241231">
  <xs:import namespace="http://fasb.org/srt/2024" schemaLocation="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2024" schemaLocation="https://xbrl.sec.gov/country/2024/country-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/cyd-af-sub/2024" schemaLocation="https://xbrl.sec.gov/cyd/2024/cyd-af-sub-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2024" schemaLocation="https://xbrl.sec.gov/dei/2024/dei-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="qlys-20241231_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="qlys-20241231_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="qlys-20241231_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="qlys-20241231_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://www.qualys.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AuditInformation" roleURI="http://www.qualys.com/role/AuditInformation">
        <link:definition>0000002 - Document - Audit Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedBalanceSheets" roleURI="http://www.qualys.com/role/ConsolidatedBalanceSheets">
        <link:definition>9952151 - Statement - Consolidated Balance Sheets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedBalanceSheetsParenthetical" roleURI="http://www.qualys.com/role/ConsolidatedBalanceSheetsParenthetical">
        <link:definition>9952152 - Statement - Consolidated Balance Sheets (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofOperations" roleURI="http://www.qualys.com/role/ConsolidatedStatementsofOperations">
        <link:definition>9952153 - Statement - Consolidated Statements of Operations</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofComprehensiveIncome" roleURI="http://www.qualys.com/role/ConsolidatedStatementsofComprehensiveIncome">
        <link:definition>9952154 - Statement - Consolidated Statements of Comprehensive Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofCashFlows" roleURI="http://www.qualys.com/role/ConsolidatedStatementsofCashFlows">
        <link:definition>9952155 - Statement - Consolidated Statements of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofStockholdersEquity" roleURI="http://www.qualys.com/role/ConsolidatedStatementsofStockholdersEquity">
        <link:definition>9952156 - Statement - Consolidated Statements of Stockholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="TheCompanyandSummaryofSignificantAccountingPolicies" roleURI="http://www.qualys.com/role/TheCompanyandSummaryofSignificantAccountingPolicies">
        <link:definition>9952157 - Disclosure - The Company and Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstruments" roleURI="http://www.qualys.com/role/FairValueofFinancialInstruments">
        <link:definition>9952158 - Disclosure - Fair Value of Financial Instruments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLoss" roleURI="http://www.qualys.com/role/AccumulatedOtherComprehensiveIncomeLoss">
        <link:definition>9952159 - Disclosure - Accumulated Other Comprehensive Income (Loss)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyandEquipmentNet" roleURI="http://www.qualys.com/role/PropertyandEquipmentNet">
        <link:definition>9952160 - Disclosure - Property and Equipment, Net</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomers" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomers">
        <link:definition>9952161 - Disclosure - Revenue from Contracts with Customers</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Acquisitions" roleURI="http://www.qualys.com/role/Acquisitions">
        <link:definition>9952162 - Disclosure - Acquisitions</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsNet" roleURI="http://www.qualys.com/role/IntangibleAssetsNet">
        <link:definition>9952163 - Disclosure - Intangible Assets, Net</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Leases" roleURI="http://www.qualys.com/role/Leases">
        <link:definition>9952164 - Disclosure - Leases</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentandContingencies" roleURI="http://www.qualys.com/role/CommitmentandContingencies">
        <link:definition>9952165 - Disclosure - Commitment and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensation" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensation">
        <link:definition>9952166 - Disclosure - Stockholders' Equity and Stock-based Compensation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefitPlan" roleURI="http://www.qualys.com/role/EmployeeBenefitPlan">
        <link:definition>9952167 - Disclosure - Employee Benefit Plan</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxes" roleURI="http://www.qualys.com/role/IncomeTaxes">
        <link:definition>9952168 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentandGeographicAreaInformation" roleURI="http://www.qualys.com/role/SegmentandGeographicAreaInformation">
        <link:definition>9952169 - Disclosure - Segment and Geographic Area Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShare" roleURI="http://www.qualys.com/role/NetIncomePerShare">
        <link:definition>9952170 - Disclosure - Net Income Per Share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="TheCompanyandSummaryofSignificantAccountingPoliciesPolicies" roleURI="http://www.qualys.com/role/TheCompanyandSummaryofSignificantAccountingPoliciesPolicies">
        <link:definition>9955511 - Disclosure - The Company and Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsTables" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsTables">
        <link:definition>9955512 - Disclosure - Fair Value of Financial Instruments (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLossTables" roleURI="http://www.qualys.com/role/AccumulatedOtherComprehensiveIncomeLossTables">
        <link:definition>9955513 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyandEquipmentNetTables" roleURI="http://www.qualys.com/role/PropertyandEquipmentNetTables">
        <link:definition>9955514 - Disclosure - Property and Equipment, Net (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersTables" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomersTables">
        <link:definition>9955515 - Disclosure - Revenue from Contracts with Customers (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsNetTables" roleURI="http://www.qualys.com/role/IntangibleAssetsNetTables">
        <link:definition>9955516 - Disclosure - Intangible Assets, Net (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeasesTables" roleURI="http://www.qualys.com/role/LeasesTables">
        <link:definition>9955517 - Disclosure - Leases (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentandContingenciesTables" roleURI="http://www.qualys.com/role/CommitmentandContingenciesTables">
        <link:definition>9955518 - Disclosure - Commitment and Contingencies (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationTables" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationTables">
        <link:definition>9955519 - Disclosure - Stockholders' Equity and Stock-based Compensation (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesTables" roleURI="http://www.qualys.com/role/IncomeTaxesTables">
        <link:definition>9955520 - Disclosure - Income Taxes (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentandGeographicAreaInformationTables" roleURI="http://www.qualys.com/role/SegmentandGeographicAreaInformationTables">
        <link:definition>9955521 - Disclosure - Segment and Geographic Area Information (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShareTables" roleURI="http://www.qualys.com/role/NetIncomePerShareTables">
        <link:definition>9955522 - Disclosure - Net Income Per Share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="TheCompanyandSummaryofSignificantAccountingPoliciesDetails" roleURI="http://www.qualys.com/role/TheCompanyandSummaryofSignificantAccountingPoliciesDetails">
        <link:definition>9955523 - Disclosure - The Company and Summary of Significant Accounting Policies (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsFairValueHierarchyDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsFairValueHierarchyDetails">
        <link:definition>9955524 - Disclosure - Fair Value of Financial Instruments - Fair Value Hierarchy (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsCashandCashEquivalentsDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsCashandCashEquivalentsDetails">
        <link:definition>9955525 - Disclosure - Fair Value of Financial Instruments - Cash and Cash Equivalents (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsSummaryofSecuritiesinUnrealizedLossPositionsDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsSummaryofSecuritiesinUnrealizedLossPositionsDetails">
        <link:definition>9955526 - Disclosure - Fair Value of Financial Instruments - Summary of Securities in Unrealized Loss Positions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsSummaryoftheFairValueofMarketableSecuritiesDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsSummaryoftheFairValueofMarketableSecuritiesDetails">
        <link:definition>9955527 - Disclosure - Fair Value of Financial Instruments - Summary of the Fair Value of Marketable Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsNarrativeDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsNarrativeDetails">
        <link:definition>9955528 - Disclosure - Fair Value of Financial Instruments - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsSummaryofDerivativeFinancialInstrumentsDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsSummaryofDerivativeFinancialInstrumentsDetails">
        <link:definition>9955529 - Disclosure - Fair Value of Financial Instruments - Summary of Derivative Financial Instruments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueofFinancialInstrumentsAmountsRecognizedInStatementofOperationsDetails" roleURI="http://www.qualys.com/role/FairValueofFinancialInstrumentsAmountsRecognizedInStatementofOperationsDetails">
        <link:definition>9955530 - Disclosure - Fair Value of Financial Instruments - Amounts Recognized In Statement of Operations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLossAccumulatedOtherComprehensiveIncomeLossDetails" roleURI="http://www.qualys.com/role/AccumulatedOtherComprehensiveIncomeLossAccumulatedOtherComprehensiveIncomeLossDetails">
        <link:definition>9955531 - Disclosure - Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income (Loss) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLossAmountsReclassifiedfromAOCIDetails" roleURI="http://www.qualys.com/role/AccumulatedOtherComprehensiveIncomeLossAmountsReclassifiedfromAOCIDetails">
        <link:definition>9955532 - Disclosure - Accumulated Other Comprehensive Income (Loss) - Amounts Reclassified from AOCI (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyandEquipmentNetPropertyandEquipmentNetDetails" roleURI="http://www.qualys.com/role/PropertyandEquipmentNetPropertyandEquipmentNetDetails">
        <link:definition>9955533 - Disclosure - Property and Equipment, Net - Property and Equipment, Net (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PropertyandEquipmentNetNarrativeDetails" roleURI="http://www.qualys.com/role/PropertyandEquipmentNetNarrativeDetails">
        <link:definition>9955534 - Disclosure - Property and Equipment, Net - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersNarrativeDetails" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomersNarrativeDetails">
        <link:definition>9955535 - Disclosure - Revenue from Contracts with Customers - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersExpectedRevenuefromAllRemainingPerformanceObligationsDetails" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomersExpectedRevenuefromAllRemainingPerformanceObligationsDetails">
        <link:definition>9955536 - Disclosure - Revenue from Contracts with Customers - Expected Revenue from All Remaining Performance Obligations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersExpectedRevenuefromAllRemainingPerformanceObligationsDetails_1" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomersExpectedRevenuefromAllRemainingPerformanceObligationsDetails_1">
        <link:definition>9955536 - Disclosure - Revenue from Contracts with Customers - Expected Revenue from All Remaining Performance Obligations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersRevenuebySalesChannelDetails" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomersRevenuebySalesChannelDetails">
        <link:definition>9955537 - Disclosure - Revenue from Contracts with Customers - Revenue by Sales Channel (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RevenuefromContractswithCustomersCapitalizedCosttoObtainContractsCurrentandNoncurrentDetails" roleURI="http://www.qualys.com/role/RevenuefromContractswithCustomersCapitalizedCosttoObtainContractsCurrentandNoncurrentDetails">
        <link:definition>9955538 - Disclosure - Revenue from Contracts with Customers - Capitalized Cost to Obtain Contracts, Current and Noncurrent (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AcquisitionsDetails" roleURI="http://www.qualys.com/role/AcquisitionsDetails">
        <link:definition>9955539 - Disclosure - Acquisitions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsNetCarryingValueofIntangibleAssetsDetails" roleURI="http://www.qualys.com/role/IntangibleAssetsNetCarryingValueofIntangibleAssetsDetails">
        <link:definition>9955540 - Disclosure - Intangible Assets, Net - Carrying Value of Intangible Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsNetNarrativeDetails" roleURI="http://www.qualys.com/role/IntangibleAssetsNetNarrativeDetails">
        <link:definition>9955541 - Disclosure - Intangible Assets, Net- Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IntangibleAssetsNetExpectedAmortizationExpenseinFuturePeriodsDetails" roleURI="http://www.qualys.com/role/IntangibleAssetsNetExpectedAmortizationExpenseinFuturePeriodsDetails">
        <link:definition>9955542 - Disclosure - Intangible Assets, Net - Expected Amortization Expense in Future Periods (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeasesNarrativeDetails" roleURI="http://www.qualys.com/role/LeasesNarrativeDetails">
        <link:definition>9955543 - Disclosure - Leases - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeasesSupplementalCashFlowInformationDetails" roleURI="http://www.qualys.com/role/LeasesSupplementalCashFlowInformationDetails">
        <link:definition>9955544 - Disclosure - Leases - Supplemental Cash Flow Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeasesWeightedAverageRemainingLeaseTermandWeightedAverageDiscountRateDetails" roleURI="http://www.qualys.com/role/LeasesWeightedAverageRemainingLeaseTermandWeightedAverageDiscountRateDetails">
        <link:definition>9955545 - Disclosure - Leases - Weighted Average Remaining Lease Term and Weighted Average Discount Rate (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeasesMinimumAnnualLeasePaymentsDetails" roleURI="http://www.qualys.com/role/LeasesMinimumAnnualLeasePaymentsDetails">
        <link:definition>9955546 - Disclosure - Leases - Minimum Annual Lease Payments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LeasesMinimumAnnualLeasePaymentsDetails_1" roleURI="http://www.qualys.com/role/LeasesMinimumAnnualLeasePaymentsDetails_1">
        <link:definition>9955546 - Disclosure - Leases - Minimum Annual Lease Payments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CommitmentandContingenciesDetails" roleURI="http://www.qualys.com/role/CommitmentandContingenciesDetails">
        <link:definition>9955547 - Disclosure - Commitment and Contingencies (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationPreferredStockDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationPreferredStockDetails">
        <link:definition>9955548 - Disclosure - Stockholders' Equity and Stock-based Compensation - Preferred Stock (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationEquityIncentivePlanDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationEquityIncentivePlanDetails">
        <link:definition>9955549 - Disclosure - Stockholders' Equity and Stock-based Compensation - Equity Incentive Plan (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationFairValueAssumptionsStockOptionsDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationFairValueAssumptionsStockOptionsDetails">
        <link:definition>9955550 - Disclosure - Stockholders' Equity and Stock-based Compensation - Fair Value Assumptions, Stock Options (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationSharebasedCompensationandStockOptionsActivityDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationSharebasedCompensationandStockOptionsActivityDetails">
        <link:definition>9955551 - Disclosure - Stockholders' Equity and Stock-based Compensation - Share-based Compensation and Stock Options Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationSummaryofRestrictedStockUnitActivityDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationSummaryofRestrictedStockUnitActivityDetails">
        <link:definition>9955552 - Disclosure - Stockholders' Equity and Stock-based Compensation - Summary of Restricted Stock Unit Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationRestrictedStockUnitsDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationRestrictedStockUnitsDetails">
        <link:definition>9955553 - Disclosure - Stockholders' Equity and Stock-based Compensation - Restricted Stock Units (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationEmployeeStockPurchasePlanValuationAssumptionsDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationEmployeeStockPurchasePlanValuationAssumptionsDetails">
        <link:definition>9955554 - Disclosure - Stockholders' Equity and Stock-based Compensation - Employee Stock Purchase Plan, Valuation Assumptions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationSummaryofStockbasedCompensationExpenseDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationSummaryofStockbasedCompensationExpenseDetails">
        <link:definition>9955555 - Disclosure - Stockholders' Equity and Stock-based Compensation - Summary of Stock-based Compensation Expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationStockbasedCompensationDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationStockbasedCompensationDetails">
        <link:definition>9955556 - Disclosure - Stockholders' Equity and Stock-based Compensation - Stock-based Compensation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationScheduleofRepurchaseAgreementsDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationScheduleofRepurchaseAgreementsDetails">
        <link:definition>9955557 - Disclosure - Stockholders' Equity and Stock-based Compensation - Schedule of Repurchase Agreements (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockholdersEquityandStockbasedCompensationShareRepurchaseProgramDetails" roleURI="http://www.qualys.com/role/StockholdersEquityandStockbasedCompensationShareRepurchaseProgramDetails">
        <link:definition>9955558 - Disclosure - Stockholders' Equity and Stock-based Compensation - Share Repurchase Program (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="EmployeeBenefitPlanDetails" roleURI="http://www.qualys.com/role/EmployeeBenefitPlanDetails">
        <link:definition>9955559 - Disclosure - Employee Benefit Plan (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofIncomebeforeIncomeTaxDomesticandForeignDetails" roleURI="http://www.qualys.com/role/IncomeTaxesScheduleofIncomebeforeIncomeTaxDomesticandForeignDetails">
        <link:definition>9955560 - Disclosure - Income Taxes - Schedule of Income before Income Tax, Domestic and Foreign (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofComponentsofIncomeTaxExpenseBenefitDetails" roleURI="http://www.qualys.com/role/IncomeTaxesScheduleofComponentsofIncomeTaxExpenseBenefitDetails">
        <link:definition>9955561 - Disclosure - Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofEffectiveIncomeTaxRateReconciliationDetails" roleURI="http://www.qualys.com/role/IncomeTaxesScheduleofEffectiveIncomeTaxRateReconciliationDetails">
        <link:definition>9955562 - Disclosure - Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofDeferredTaxAssetsandLiabilitiesDetails" roleURI="http://www.qualys.com/role/IncomeTaxesScheduleofDeferredTaxAssetsandLiabilitiesDetails">
        <link:definition>9955563 - Disclosure - Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesNarrativeDetails" roleURI="http://www.qualys.com/role/IncomeTaxesNarrativeDetails">
        <link:definition>9955564 - Disclosure - Income Taxes - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesScheduleofUnrecognizedTaxBenefitsRollForwardDetails" roleURI="http://www.qualys.com/role/IncomeTaxesScheduleofUnrecognizedTaxBenefitsRollForwardDetails">
        <link:definition>9955565 - Disclosure - Income Taxes - Schedule of Unrecognized Tax Benefits Roll Forward (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentandGeographicAreaInformationNarrativeDetails" roleURI="http://www.qualys.com/role/SegmentandGeographicAreaInformationNarrativeDetails">
        <link:definition>9955566 - Disclosure - Segment and Geographic Area Information - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentandGeographicAreaInformationReportedSegmentRevenueSegmentProfitOrLossDetails" roleURI="http://www.qualys.com/role/SegmentandGeographicAreaInformationReportedSegmentRevenueSegmentProfitOrLossDetails">
        <link:definition>9955567 - Disclosure - Segment and Geographic Area Information - Reported Segment Revenue, Segment Profit Or Loss (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentandGeographicAreaInformationRevenueandPropertyandEquipmentNetbyGeographicAreaDetails" roleURI="http://www.qualys.com/role/SegmentandGeographicAreaInformationRevenueandPropertyandEquipmentNetbyGeographicAreaDetails">
        <link:definition>9955568 - Disclosure - Segment and Geographic Area Information - Revenue and Property and Equipment, Net by Geographic Area (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShareBasicandDilutedNetIncomePerShareDetails" roleURI="http://www.qualys.com/role/NetIncomePerShareBasicandDilutedNetIncomePerShareDetails">
        <link:definition>9955569 - Disclosure - Net Income Per Share - Basic and Diluted Net Income Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomePerShareAntidilutiveNetIncomePerShareDetails" roleURI="http://www.qualys.com/role/NetIncomePerShareAntidilutiveNetIncomePerShareDetails">
        <link:definition>9955570 - Disclosure - Net Income Per Share - Anti-dilutive Net Income Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="qlys_AuditorInformationAbstract" abstract="true" name="AuditorInformationAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="qlys_AccrualForRepurchaseOfCommonStock" abstract="false" name="AccrualForRepurchaseOfCommonStock" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_StockIssuedDuringPeriodSharesRestrictedStockAwardVested" abstract="false" name="StockIssuedDuringPeriodSharesRestrictedStockAwardVested" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="qlys_DescriptionOfBusinessPolicyPolicyTextBlock" abstract="false" name="DescriptionOfBusinessPolicyPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="qlys_CashCashEquivalentsAndShorttermAndLongtermInvestmentsPolicyPolicyTextBlock" abstract="false" name="CashCashEquivalentsAndShorttermAndLongtermInvestmentsPolicyPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="qlys_AssetAcquisitionsPolicyTextBlock" abstract="false" name="AssetAcquisitionsPolicyTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="qlys_CashAndCashEquivalentsAndDebtSecuritiesAvailableforsaleAmortizedCostToFairValueTableTextBlock" abstract="false" name="CashAndCashEquivalentsAndDebtSecuritiesAvailableforsaleAmortizedCostToFairValueTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="qlys_AssetsAndLiabilitiesLesseeTableTextBlock" abstract="false" name="AssetsAndLiabilitiesLesseeTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="qlys_ShareRepurchaseProgramTableTextBlock" abstract="false" name="ShareRepurchaseProgramTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="qlys_SecurityDepositsMember" abstract="true" name="SecurityDepositsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_CashHeldInEscrowWithBlueHexagonAcquisitionMember" abstract="true" name="CashHeldInEscrowWithBlueHexagonAcquisitionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ScannerAppliancesMember" abstract="true" name="ScannerAppliancesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ForeignExchangeContractsForGBPAndEuroMember" abstract="true" name="ForeignExchangeContractsForGBPAndEuroMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ForeignExchangeContractsForINRMember" abstract="true" name="ForeignExchangeContractsForINRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ScannerAppliancesAndOtherComputerEquipmentSubjectToSubscriptionMember" abstract="true" name="ScannerAppliancesAndOtherComputerEquipmentSubjectToSubscriptionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ScannerAppliancesAndOtherComputerEquipmentNotPlacedInServiceMember" abstract="true" name="ScannerAppliancesAndOtherComputerEquipmentNotPlacedInServiceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_DepreciationDepletionAndAmortizationExcludingIntangibleAssetAmortization" abstract="false" name="DepreciationDepletionAndAmortizationExcludingIntangibleAssetAmortization" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_BlueHexagonIncMember" abstract="true" name="BlueHexagonIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_AssembledWorkforceMember" abstract="true" name="AssembledWorkforceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue" abstract="false" name="AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_AssetAcquisitionAcquisitionRelatedCosts" abstract="false" name="AssetAcquisitionAcquisitionRelatedCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFiniteLivedIntangibles" abstract="false" name="AssetAcquisitionRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedFiniteLivedIntangibles" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_The2012EquityIncentivePlanMember" abstract="true" name="The2012EquityIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_The2021EmployeeStockPurchasePlanMember" abstract="true" name="The2021EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseShares" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreaseShares" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreasePercentOfSharesOutstanding" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorizedAnnualIncreasePercentOfSharesOutstanding" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="qlys_EmployeeStockPurchasePlanPercentageOfEligibleCompensationContributable" abstract="false" name="EmployeeStockPurchasePlanPercentageOfEligibleCompensationContributable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="qlys_PerformanceBasedRestrictedStockUnitsMember" abstract="true" name="PerformanceBasedRestrictedStockUnitsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ExecutiveOfficer1Member" abstract="true" name="ExecutiveOfficer1Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ExecutiveOfficer2Member" abstract="true" name="ExecutiveOfficer2Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ExecutiveOfficer3Member" abstract="true" name="ExecutiveOfficer3Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ExecutiveOfficer4Member" abstract="true" name="ExecutiveOfficer4Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestNumberOfShares" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExpectedToVestNumberOfShares" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="qlys_ExpectedToVestWeightedAverageGrantDateFairValue" abstract="false" name="ExpectedToVestWeightedAverageGrantDateFairValue" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:perShareItemType"/>
  <xs:element id="qlys_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPercentage" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="qlys_ShareBasedCompensationPercentageOfSharesThatWillVestUponTrigger" abstract="false" name="ShareBasedCompensationPercentageOfSharesThatWillVestUponTrigger" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="qlys_ESPPSharesMember" abstract="true" name="ESPPSharesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_StockRepurchaseProgramRollForward" abstract="true" name="StockRepurchaseProgramRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="qlys_StockRepurchaseProgramIncreasedAdditionalAuthorizedAmount" abstract="false" name="StockRepurchaseProgramIncreasedAdditionalAuthorizedAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_StockRepurchaseProgramAdditionalAuthorizedAmount" abstract="false" name="StockRepurchaseProgramAdditionalAuthorizedAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_DeferredTaxAssetsOperatingLeaseLiabilities" abstract="false" name="DeferredTaxAssetsOperatingLeaseLiabilities" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_DeferredTaxLiabilitiesDeferredCommission" abstract="false" name="DeferredTaxLiabilitiesDeferredCommission" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="qlys_ReportableSegmentMember" abstract="true" name="ReportableSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="qlys_OtherGeographicAreasMember" abstract="true" name="OtherGeographicAreasMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="qlys_EmployeeStockPurchasePlanSharesMember" abstract="true" name="EmployeeStockPurchasePlanSharesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
