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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:d535918a-7857-4403-95f4-8ec3b20492d1,g:f1ff69d7-090e-4b3e-8d59-19d9b34e7174-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:appn="http://www.appian.com/20240331" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types1="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.appian.com/20240331">
  <xs:import namespace="http://fasb.org/srt/2023" schemaLocation="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2023" schemaLocation="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd"/>
  <xs:import namespace="http://www.w3.org/1999/xlink" schemaLocation="http://www.xbrl.org/2003/xlink-2003-12-31.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.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2023" schemaLocation="https://xbrl.sec.gov/country/2023/country-2023.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2023" schemaLocation="https://xbrl.sec.gov/dei/2023/dei-2023.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="appn-20240331_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="appn-20240331_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="appn-20240331_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="appn-20240331_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="CoverPage" roleURI="http://www.appian.com/role/CoverPage">
        <link:definition>0000001 - Document - Cover Page</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.appian.com/role/CONSOLIDATEDBALANCESHEETS">
        <link:definition>0000002 - 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.appian.com/role/CONSOLIDATEDBALANCESHEETSParenthetical">
        <link:definition>0000003 - 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.appian.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS">
        <link:definition>0000004 - 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="CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS" roleURI="http://www.appian.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS">
        <link:definition>0000005 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE 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="CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSDEFICITEQUITY" roleURI="http://www.appian.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSDEFICITEQUITY">
        <link:definition>0000006 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' (DEFICIT) 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="CONSOLIDATEDSTATEMENTSOFCASHFLOWS" roleURI="http://www.appian.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS">
        <link:definition>0000007 - 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="OrganizationandDescriptionofBusiness" roleURI="http://www.appian.com/role/OrganizationandDescriptionofBusiness">
        <link:definition>0000008 - Disclosure - Organization and Description of Business</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="AccountingPolicies" roleURI="http://www.appian.com/role/AccountingPolicies">
        <link:definition>0000009 - Disclosure - 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="Revenue" roleURI="http://www.appian.com/role/Revenue">
        <link:definition>0000010 - Disclosure - Revenue</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.appian.com/role/Leases">
        <link:definition>0000011 - 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="GoodwillandIntangibleAssets" roleURI="http://www.appian.com/role/GoodwillandIntangibleAssets">
        <link:definition>0000012 - Disclosure - Goodwill and Intangible Assets</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.appian.com/role/PropertyandEquipmentnet">
        <link:definition>0000013 - 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="AccruedExpenses" roleURI="http://www.appian.com/role/AccruedExpenses">
        <link:definition>0000014 - Disclosure - Accrued Expenses</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="Debt" roleURI="http://www.appian.com/role/Debt">
        <link:definition>0000015 - Disclosure - Debt</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.appian.com/role/IncomeTaxes">
        <link:definition>0000016 - 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="StockBasedCompensation" roleURI="http://www.appian.com/role/StockBasedCompensation">
        <link:definition>0000017 - Disclosure - 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="BasicandDilutedLossperShare" roleURI="http://www.appian.com/role/BasicandDilutedLossperShare">
        <link:definition>0000018 - Disclosure - Basic and Diluted Loss 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="CommitmentsContingenciesandOtherMatters" roleURI="http://www.appian.com/role/CommitmentsContingenciesandOtherMatters">
        <link:definition>0000019 - Disclosure - Commitments, Contingencies, and Other Matters</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="SegmentandGeographicInformation" roleURI="http://www.appian.com/role/SegmentandGeographicInformation">
        <link:definition>0000020 - Disclosure - Segment and Geographic 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="InvestmentsandFairValueMeasurements" roleURI="http://www.appian.com/role/InvestmentsandFairValueMeasurements">
        <link:definition>0000021 - Disclosure - Investments and Fair Value Measurements</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="AccountingPoliciesPolicies" roleURI="http://www.appian.com/role/AccountingPoliciesPolicies">
        <link:definition>9954471 - Disclosure - 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="AccountingPoliciesTables" roleURI="http://www.appian.com/role/AccountingPoliciesTables">
        <link:definition>9954472 - Disclosure - Accounting Policies (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="RevenueTables" roleURI="http://www.appian.com/role/RevenueTables">
        <link:definition>9954473 - Disclosure - Revenue (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.appian.com/role/LeasesTables">
        <link:definition>9954474 - 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="GoodwillandIntangibleAssetsTables" roleURI="http://www.appian.com/role/GoodwillandIntangibleAssetsTables">
        <link:definition>9954475 - Disclosure - Goodwill and Intangible Assets (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.appian.com/role/PropertyandEquipmentnetTables">
        <link:definition>9954476 - 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="AccruedExpensesTables" roleURI="http://www.appian.com/role/AccruedExpensesTables">
        <link:definition>9954477 - Disclosure - Accrued Expenses (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="DebtTables" roleURI="http://www.appian.com/role/DebtTables">
        <link:definition>9954478 - Disclosure - Debt (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="StockBasedCompensationTables" roleURI="http://www.appian.com/role/StockBasedCompensationTables">
        <link:definition>9954479 - Disclosure - 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="BasicandDilutedLossperShareTables" roleURI="http://www.appian.com/role/BasicandDilutedLossperShareTables">
        <link:definition>9954480 - Disclosure - Basic and Diluted Loss 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="SegmentandGeographicInformationTables" roleURI="http://www.appian.com/role/SegmentandGeographicInformationTables">
        <link:definition>9954481 - Disclosure - Segment and Geographic 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="InvestmentsandFairValueMeasurementsTables" roleURI="http://www.appian.com/role/InvestmentsandFairValueMeasurementsTables">
        <link:definition>9954482 - Disclosure - Investments and Fair Value Measurements (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="AccountingPoliciesAdditionalInformationDetails" roleURI="http://www.appian.com/role/AccountingPoliciesAdditionalInformationDetails">
        <link:definition>9954483 - Disclosure - Accounting Policies - Additional 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="AccountingPoliciesCashCashEquivalentsandRestrictedCashDetails" roleURI="http://www.appian.com/role/AccountingPoliciesCashCashEquivalentsandRestrictedCashDetails">
        <link:definition>9954484 - Disclosure - Accounting Policies - Cash, Cash Equivalents, and Restricted Cash (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="RevenueRevenuebyServicesDetails" roleURI="http://www.appian.com/role/RevenueRevenuebyServicesDetails">
        <link:definition>9954485 - Disclosure - Revenue - Revenue by Services (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="RevenueAdditionalInformationDetails" roleURI="http://www.appian.com/role/RevenueAdditionalInformationDetails">
        <link:definition>9954486 - Disclosure - Revenue - Additional 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="RevenueAdditionalInformationDetails_1" roleURI="http://www.appian.com/role/RevenueAdditionalInformationDetails_1">
        <link:definition>9954486 - Disclosure - Revenue - Additional 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="RevenueScheduleofContractAssetandContractLiabilityDetails" roleURI="http://www.appian.com/role/RevenueScheduleofContractAssetandContractLiabilityDetails">
        <link:definition>9954487 - Disclosure - Revenue - Schedule of Contract Asset and Contract Liability (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="LeasesAdditionalInformationDetails" roleURI="http://www.appian.com/role/LeasesAdditionalInformationDetails">
        <link:definition>9954488 - Disclosure - Leases - Additional 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="LeasesComponentsofLeaseExpenseDetails" roleURI="http://www.appian.com/role/LeasesComponentsofLeaseExpenseDetails">
        <link:definition>9954489 - Disclosure - Leases - Components of Lease 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="LeasesSupplementalBalanceSheetInformationDetails" roleURI="http://www.appian.com/role/LeasesSupplementalBalanceSheetInformationDetails">
        <link:definition>9954490 - Disclosure - Leases - Supplemental Balance Sheet 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="LeasesSupplementalCashFlowInformationDetails" roleURI="http://www.appian.com/role/LeasesSupplementalCashFlowInformationDetails">
        <link:definition>9954491 - 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="LeasesMaturitiesofLeaseLiabilitiesDetails" roleURI="http://www.appian.com/role/LeasesMaturitiesofLeaseLiabilitiesDetails">
        <link:definition>9954492 - Disclosure - Leases - Maturities of Lease 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="LeasesMaturitiesofLeaseLiabilitiesDetails_1" roleURI="http://www.appian.com/role/LeasesMaturitiesofLeaseLiabilitiesDetails_1">
        <link:definition>9954492 - Disclosure - Leases - Maturities of Lease 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="GoodwillandIntangibleAssetsScheduleofGoodwillDetails" roleURI="http://www.appian.com/role/GoodwillandIntangibleAssetsScheduleofGoodwillDetails">
        <link:definition>9954493 - Disclosure - Goodwill and Intangible Assets - Schedule of Goodwill (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="GoodwillandIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" roleURI="http://www.appian.com/role/GoodwillandIntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails">
        <link:definition>9954494 - Disclosure - Goodwill and Intangible Assets - Schedule of Finite-Lived 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="GoodwillandIntangibleAssetsAdditionalInformationDetails" roleURI="http://www.appian.com/role/GoodwillandIntangibleAssetsAdditionalInformationDetails">
        <link:definition>9954495 - Disclosure - Goodwill and Intangible Assets - Additional 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="GoodwillandIntangibleAssetsScheduleofFutureAmortizationExpenseDetails" roleURI="http://www.appian.com/role/GoodwillandIntangibleAssetsScheduleofFutureAmortizationExpenseDetails">
        <link:definition>9954496 - Disclosure - Goodwill and Intangible Assets - Schedule of Future Amortization 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="PropertyandEquipmentnetScheduleofPropertyandEquipmentDetails" roleURI="http://www.appian.com/role/PropertyandEquipmentnetScheduleofPropertyandEquipmentDetails">
        <link:definition>9954497 - Disclosure - Property and Equipment, net - Schedule of Property and Equipment (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="PropertyandEquipmentnetAdditionalInformationDetails" roleURI="http://www.appian.com/role/PropertyandEquipmentnetAdditionalInformationDetails">
        <link:definition>9954498 - Disclosure - Property and Equipment, net - Additional 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="AccruedExpensesDetails" roleURI="http://www.appian.com/role/AccruedExpensesDetails">
        <link:definition>9954499 - Disclosure - Accrued Expenses (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="DebtAdditionalInformationDetails" roleURI="http://www.appian.com/role/DebtAdditionalInformationDetails">
        <link:definition>9954500 - Disclosure - Debt - Additional 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="DebtOutstandingLongtermDebtDetails" roleURI="http://www.appian.com/role/DebtOutstandingLongtermDebtDetails">
        <link:definition>9954501 - Disclosure - Debt - Outstanding Long-term Debt (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="IncomeTaxesDetails" roleURI="http://www.appian.com/role/IncomeTaxesDetails">
        <link:definition>9954502 - Disclosure - Income Taxes (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="StockBasedCompensationAdditionalInformationDetails" roleURI="http://www.appian.com/role/StockBasedCompensationAdditionalInformationDetails">
        <link:definition>9954503 - Disclosure - Stock-Based Compensation - Additional 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="StockBasedCompensationScheduleofStockbasedCompensationExpenseIncludedinCondensedConsolidatedStatementsofOperationsDetails" roleURI="http://www.appian.com/role/StockBasedCompensationScheduleofStockbasedCompensationExpenseIncludedinCondensedConsolidatedStatementsofOperationsDetails">
        <link:definition>9954504 - Disclosure - Stock-Based Compensation - Schedule of Stock-based Compensation Expense Included in Condensed Consolidated Statements 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="BasicandDilutedLossperShareDetails" roleURI="http://www.appian.com/role/BasicandDilutedLossperShareDetails">
        <link:definition>9954505 - Disclosure - Basic and Diluted Loss 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="CommitmentsContingenciesandOtherMattersDetails" roleURI="http://www.appian.com/role/CommitmentsContingenciesandOtherMattersDetails">
        <link:definition>9954506 - Disclosure - Commitments, Contingencies, and Other Matters (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="SegmentandGeographicInformationScheduleofRevenuebyGeographyDetails" roleURI="http://www.appian.com/role/SegmentandGeographicInformationScheduleofRevenuebyGeographyDetails">
        <link:definition>9954507 - Disclosure - Segment and Geographic Information - Schedule of Revenue by Geography (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="SegmentandGeographicInformationAdditionalInformationDetails" roleURI="http://www.appian.com/role/SegmentandGeographicInformationAdditionalInformationDetails">
        <link:definition>9954508 - Disclosure - Segment and Geographic Information - Additional 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="InvestmentsandFairValueMeasurementsComponentsofInvestmentsDetails" roleURI="http://www.appian.com/role/InvestmentsandFairValueMeasurementsComponentsofInvestmentsDetails">
        <link:definition>9954509 - Disclosure - Investments and Fair Value Measurements - Components of Investments (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="InvestmentsandFairValueMeasurementsAdditionalInformationDetails" roleURI="http://www.appian.com/role/InvestmentsandFairValueMeasurementsAdditionalInformationDetails">
        <link:definition>9954510 - Disclosure - Investments and Fair Value Measurements - Additional Information (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="appn_TermLoanFacilityMember" abstract="true" name="TermLoanFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_PaymentsForPurchaseObligation" abstract="false" name="PaymentsForPurchaseObligation" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_IncomeTaxesTable" abstract="true" name="IncomeTaxesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="appn_DeferredCommissionNoncurrent" abstract="false" name="DeferredCommissionNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_SwinglineSubFacilityMember" abstract="true" name="SwinglineSubFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_CloudSubscriptionsMember" abstract="true" name="CloudSubscriptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_FederalGovernmentAgenciesMember" abstract="true" name="FederalGovernmentAgenciesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_StatutoryPostJudgementInterestOnJudgmentalMember" abstract="true" name="StatutoryPostJudgementInterestOnJudgmentalMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_ProfessionalServicesMember" abstract="true" name="ProfessionalServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_AccruedHostingCostsCurrent" abstract="false" name="AccruedHostingCostsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_MisappropriationOfTradeSecretsMember" abstract="true" name="MisappropriationOfTradeSecretsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_LitigationAppealProcessPeriod" abstract="false" name="LitigationAppealProcessPeriod" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="appn_DeferredCommissionsCurrent" abstract="false" name="DeferredCommissionsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_AccruedCapitalExpenditures" abstract="false" name="AccruedCapitalExpenditures" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_IncreaseDecreaseInOperatingLeaseAssetsAndLiabilities" abstract="false" name="IncreaseDecreaseInOperatingLeaseAssetsAndLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" abstract="false" name="SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="appn_SubscriptionsSoftwareAndSupportMember" abstract="true" name="SubscriptionsSoftwareAndSupportMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_IncreaseDecreaseInDeferredCommissions" abstract="false" name="IncreaseDecreaseInDeferredCommissions" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_GovernmentAgenciesMember" abstract="true" name="GovernmentAgenciesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_ForeignCustomersMember" abstract="true" name="ForeignCustomersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="appn_YouyongZouLitigationMember" abstract="true" name="YouyongZouLitigationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_SoftwareAsServiceSubscriptionContractsTerm" abstract="false" name="SoftwareAsServiceSubscriptionContractsTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="appn_DocumentAndEntityInformationTable" abstract="true" name="DocumentAndEntityInformationTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="appn_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" abstract="false" name="FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_TenantImprovementsReimbursementsReceived" abstract="false" name="TenantImprovementsReimbursementsReceived" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_AccruedThirdPartyLicenseFee" abstract="false" name="AccruedThirdPartyLicenseFee" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_LitigationJudgmentPreservationInsuranceNoncurrent" abstract="false" name="LitigationJudgmentPreservationInsuranceNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_SummaryOfSignificantAccountingPoliciesLineItems" abstract="true" name="SummaryOfSignificantAccountingPoliciesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="appn_DocumentAndEntityInformationLineItems" abstract="true" name="DocumentAndEntityInformationLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="appn_TermLicenseSubscriptionsMember" abstract="true" name="TermLicenseSubscriptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_SummaryOfSignificantAccountingPoliciesTable" abstract="true" name="SummaryOfSignificantAccountingPoliciesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="appn_LitigationJudgmentPreservationInsuranceCost" abstract="false" name="LitigationJudgmentPreservationInsuranceCost" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_LitigationJudgmentPreservationInsuranceExpense" abstract="false" name="LitigationJudgmentPreservationInsuranceExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_AssetsAndLiabilitiesLesseeTableTextBlock" abstract="false" name="AssetsAndLiabilitiesLesseeTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="appn_PegasystemsLitigationMember" abstract="true" name="PegasystemsLitigationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_CashAndInvestmentsFairValueDisclosure" abstract="false" name="CashAndInvestmentsFairValueDisclosure" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_ComputerSoftwareAndHardwareMember" abstract="true" name="ComputerSoftwareAndHardwareMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="appn_CheckingOrOvernightRepurchaseInvestmentAccountsMember" abstract="true" name="CheckingOrOvernightRepurchaseInvestmentAccountsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="appn_AccruedContractEmploymentCurrent" abstract="false" name="AccruedContractEmploymentCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_AccruedLegalCosts" abstract="false" name="AccruedLegalCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_SecuredTermLoanFacilityMember" abstract="true" name="SecuredTermLoanFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_LitigationJudgmentPreservationInsuranceCurrent" abstract="false" name="LitigationJudgmentPreservationInsuranceCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_OperatingLeaseInterestExpense" abstract="false" name="OperatingLeaseInterestExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_CustomerOneMember" abstract="true" name="CustomerOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="appn_IncomeTaxesLineItems" abstract="true" name="IncomeTaxesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="appn_MaintenanceAndSupportMember" abstract="true" name="MaintenanceAndSupportMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_AttorneysFeesAssociatedMember" abstract="true" name="AttorneysFeesAssociatedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_IncreaseDecreaseInAccruedCompensationAndRelatedBenefits" abstract="false" name="IncreaseDecreaseInAccruedCompensationAndRelatedBenefits" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="appn_GainContingencyDamagesAwardedInterestPercentage" abstract="false" name="GainContingencyDamagesAwardedInterestPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="appn_NumberOfGovernmentAgencies" abstract="false" name="NumberOfGovernmentAgencies" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="appn_ViolationOfVirginiaComputerCrimesActMember" abstract="true" name="ViolationOfVirginiaComputerCrimesActMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="appn_JudgmentPreservationInsuranceThresholdAmount" abstract="false" name="JudgmentPreservationInsuranceThresholdAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
