| File extension Name |
extension description |
| .X | LEX Program File |
| .X | FPS Creator Model (The Game Creators Ltd.) |
| .X | REXX Script (IBM) |
| .X | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .X | Xview Object |
| .X | Stardent AVS X Image |
| .X | Direct3D Object (Microsoft Corporation) |
| .X | Amapi 3D Modeling |
| .X | Alysis SuperDisk Self-extracting Archive |
| .X | XBLite Program File |
| .X01 | Paradox Secondary Index |
| .X02 | Paradox Secondary Index |
| .X03 | Paradox Secondary Index |
| .X04 | Paradox Secondary Index |
| .X05 | Paradox Secondary Index |
| .X06 | Paradox Secondary Index |
| .X07 | Paradox Secondary Index |
| .X08 | Paradox Secondary Index |
| .X09 | Paradox Secondary Index |
| .X1 | X1 Desktop Search Saved Search File (X1 Technologies, Inc.) |
| .X10 | X Window Dump Bitmap |
| .X11 | X Windows System Window Dump Bitmap |
| .X13 | Hooligans |
| .X16 | Macromedia Program Extension |
| .X28 | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .X32 | Macromedia Program Extension (Macromedia) |
| .X3D | Xara 3D Project File (Xara) |
| .X3D | X3D File (Web3D Consortium) |
| .X3DB | X3D Binary Format File (Web3D Consortium) |
| .X3DBZ | X3D GZipped Binary Format File (Web3D Consortium) |
| .X3DV | X3D Classic VRML File (Web3D Consortium) |
| .X3DVZ | X3D GZipped Classic VRML File (Web3D Consortium) |
| .X3F | Sigma Camera RAW Picture File (Sigma) |
| .X4M | TeamLinks Mail File Data |
| .X5 | Rockwell Software Logix 5 File |
| .X64 | C64 Emulator Disk Image |
| .XA | Gear CD Suite File |
| .XA | The Sims Extensive Audio (Electronic Arts (Maxis)) |
| .XA | Extended Architecture File |
| .XA | Playstation Video (Sony Corporation of America) |
| .XA2 | Exam Editor Question Groups (Nice Productions) |
| .XAB | Xenis Mail Address Book |
| .XAB | Mail Address Book (Microsoft Corporation) |
| .XAC | GNUCash GNUCash Backup File (The GNUCash Project) |
| .XACT | XactScript File (XactCommerce) |
| .XAD | eXotic AdLib Format |
| .XADML | XML-based Application Description Information |
| .XAML | Windows Presentation Foundation Object Model XML-based Markup Language (Microsoft Corporation) |
| .XAN | xyALGEBRA File |
| .XAN | XANIA Browser |
| .XAP | Elonex ONEt+ Application File (Elonex) |
| .XAP | Xbox Dashboard Script (Microsoft Corporation) |
| .XAP | Silverlight Application Package (Microsoft Corporation) |
| .XAR | eXtensible ARchiver Archive |
| .XAR | Xara X Vector Drawing (Xara Group Limited) |
| .XAR | Corel Xara Drawing |
| .XAR | Excel AutoRecover File (Microsoft Corporation) |
| .XARC | The Longest Journey Sound File (Funcom) |
| .XAS | Playstation Video (Sony Corporation of America) |
| .XBA | xBase Website Code (Mauricio Fragoso) |
| .XBA | Timespace X200/K200 Digital Video Recorder Video File (Timespace Technology Ltd.) |
| .XBAP | Silverlight Application Package (Microsoft Corporation) |
| .XBE | Xbox Executable (Microsoft Corporation) |
| .XBEL | XML Bookmark Exchange Language (XBEL) File (SIG for XML Processing in Python) |
| .XBF | Emperor Battle for Dune |
| .XBF | Database File |
| .XBIN | RegSupreme License File (Macecraft Software) |
| .XBK | SMART Board Slide Collection (SMART Technologies Inc.) |
| .XBL | Extensible Binding Language |
| .XBL | XBLite Program File |
| .XBM | X Bitmap Graphic |
| .XBP | XBWML X-Bite.co.uk Markup Language (X-Bite.co.uk) |
| .XBS | ETAK MapBase |
| .XBW | Crossword |
| .XBX | XBox Image File (Microsoft Corporation) |
| .XB~ | IC File |
| .XC | X Server Constant Screen Image Bitmap |
| .XC2 | HPXView DACCS Configuration (Haliplex Communication Systems) |
| .XCD | WarpIN CID (Configuration, Installation, Distribution) File |
| .XCDATAMODEL | Xcode Core Data-based Data Model (Apple Inc.) |
| .XCF | GIMP Image File (The GIMP Team) |
| .XCI | Acrobat Font Mapping File (Adobe Systems Incorporated) |
| .XCK | Extended Crack File |
| .XCL | Xtree for Win Script |
| .XCM | CmapTools Exported Concept Map (IHMC) |
| .XCMD | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XCMDS | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XCN | HPXView DACCS Configuration (Haliplex Communication Systems) |
| .XCODEPROJ | Xcode Project (Apple Inc.) |
| .XCP | Xbox Compressed Package (Microsoft Corporation) |
| .XCR | Warlords Battlecry (Strategic Studies Group, Pty Ltd.) |
| .XCS | BuzzLetter Encrypted Stationery Template (StationeryCentral.com, Inc.) |
| .XCT | XVI32 Conversion File (Christian Maas) |
| .XCU | OpenOffice.org Extension Control File (OpenOffice.org Community) |
| .XCZ | BuzzLetter Zipped Collection of Encrypted Stationery Templates (StationeryCentral.com, Inc.) |
| .XD | CCS-lib.2 Examples Motif-CC File |
| .XDB | Norton AntiVirus Update File (Symantec Corporation) |
| .XDB | xText Compiled Database (Flambeaux Software) |
| .XDB | HyperCD HyperLOCK (John Galt Media, Inc.) |
| .XDC | Acrobat Printer Description (Adobe Systems Incorporated) |
| .XDC | DarkCrypTC Encrypted File Container (DarkSoftware (Alexander Myasnikov, Kolchugino)) |
| .XDD | xfit XDD Format Data File |
| .XDE | Tgif-3.0 File |
| .XDELTA | Xdelta Binary Differential File |
| .XDF | Workshare Synergy File |
| .XDF | Extended Disk Format Image |
| .XDF | Milnta APL Transfer Function |
| .XDF | ProWORX Nxt Extended Memory Data (Schneider Electric) |
| .XDF | X68000 Image File |
| .XDIM | Multi-Channel Server (MCS) Markup Editor XDIME Document (Volantis Systems Ltd.) |
| .XDK | XML Development Kit Project (Republicorp Virtual Media) |
| .XDO | OutDo Outline File (Aspevia Systems) |
| .XDO | Oracle BI Publisher Resource Tracking File (Oracle) |
| .XDP | UNIX File |
| .XDP | Playstation Media Manager For PSP File (Sony Computer Entertainment Inc.) |
| .XDP | Acrobat XML Data Package File (Adobe Systems Incorporated) |
| .XDQ | Harvest Log File (Hydro-Logic Ltd, Isodaq Division) |
| .XDR | BizTalk XML-Data Reduced Schema (Microsoft Corporation) |
| .XDRUID | XDIME Player Skin (Volantis Systems Ltd.) |
| .XDR_TOR | Insight II Binary Torsion File (Accelrys Software Inc.) |
| .XDS | LCDStudio Design (LCDStudio.com) |
| .XDS | Nintendo DS Game Maker Project File (Invisionsoft) |
| .XDS | OpenGL Performer Script |
| .XDS | XDS X-ray Detector Software |
| .XDS | Symantec Store Download Manager Partial Download (Symantec Corporation) |
| .XDSL | D-Link Router UK Firmware Update File (D-Link Systems, Inc.) |
| .XDT | Xscript Data Packet (Codec Games) |
| .XDW | Milnta APL Transfer Function |
| .XDW | DocuWorks File (Fuji Xerox Co., Ltd.) |
| .XEA | Cryptomax Encrypted Archive (Cryptomax.net) |
| .XEB | Apabi eBook |
| .XEC | Afaria (XcelleNet) |
| .XEE | Expression Encoder Preset File (Microsoft Corporation) |
| .XEF | eManager Form Data (X-Genics Ltd.) |
| .XEJ | Expression Encoder Job File (Microsoft Corporation) |
| .XEL | Expression Encoder Log File (Microsoft Corporation) |
| .XEM | eManager Metering Unit Credits for File Use (XGenics Ltd.) |
| .XEN | Xenu's Link Sleuth Saved Results File (Tilman Hausherr) |
| .XEP | XenoDream Graphics Data (XenoDream Software, LLC.) |
| .XEP | eManager File Packing Definition (XGenics Ltd.) |
| .XER | Primavera Project Management Propriety Exchange Format (Primavera Systems, Inc) |
| .XES | eManager XML UI Definition for Skins (XGenics Ltd.) |
| .XET | eManager XML Definition of eManager Process (XGenics Ltd.) |
| .XEV | eManager XML Autoupdate Definition (X-Genics Ltd) |
| .XEX | XeX Web Page Definition |
| .XEX | KERMIT Control File |
| .XEX | Renamed .EXE File |
| .XEX | Xbox Executable (Microsoft Corporation) |
| .XEZ | eManager Template Package (X-Genics Ltd.) |
| .XFB | LonMark Binary Device Interface File Format (LonMark International) |
| .XFC | Docuprint N17 Printer Firmware (Xerox) |
| .XFC | X-Fonter Font Collection File (Blacksun Software) |
| .XFD | XML Form in XFDL Format |
| .XFD | Atari Disk Image (Atari) |
| .XFD | Acu4GL Extended File Description (Acucorp, Inc.) |
| .XFDF | Acrobat Forms Document (Adobe Systems Incorporated) |
| .XFDL | XML Form in XFDL Format |
| .XFI | xICE Desktop Encrypted File (Network At Home Enterprises) |
| .XFI | LaTex Figures File |
| .XFL | Flash CS4 Exchange Format (Adobe Systems Incorporated) |
| .XFL | xICE Desktop Encrypted Folder (Network At Home Enterprises) |
| .XFM | OmniForm XML Format |
| .XFM | Audition Transform Effect (Adobe Systems Incorporated) |
| .XFN | Ventura Printer Font |
| .XFO | LonMark Optimized Device Interface File (LonMark International) |
| .XFR | Xfrog Vegetation File (greenworks organic-software) |
| .XFR | Symantec Anti-Virus Corporate Version Failed Update (Symantec Corporation) |
| .XFR | Ventura Publisher Bitmap Editor Font File |
| .XFS | Wolfteam Game File (Softnyx) |
| .XFS | GunBound (Softnyx) |
| .XFS | eRacer Sound File |
| .XFT | ChiWriter 24 Pin Printer Font |
| .XFT | LiveCycle Designer Form (Adobe Systems Incorporated) |
| .XFX | Fax File |
| .XG | XG Encryption Encryption (Mastermind Technology) |
| .XG0 | Database Index; Paradox Secondary Index |
| .XG1 | Database Index; Also XG2, XG3... |
| .XG1 | Techno Toys XG-909 MIDI Drum Machine File |
| .XG9 | Techno Toys XG-909 MIDI Drum Machine File |
| .XGL | MegaBitz Graphics Language File |
| .XGM | Techno Toys XG-909 MIDI Drum Machine File |
| .XGO | LogMate for Windows File |
| .XGO | Paradox Database-related File |
| .XGO | GeoConcept Add-On (GeoConcept SA) |
| .XGP | PicturePlayer Password Protected Files (PicturePlayer) |
| .XGR | Graph Edit XML Graph (Filter Graph Markup Language) (Microsoft Corporation) |
| .XGS | PicturePlayer Scrambled Files (PicturePlayer) |
| .XGZ | MegaBitz Vector Drawing |
| .XHD | HappyFish XML Data File (ThirstyCrow) |
| .XHDML | XML Version of HDML File |
| .XHESSIAN | Insight II Hessian File (Accelrys Software Inc.) |
| .XHT | Extensible HyperText Markup Language File |
| .XHTM | Extensible HyperText Markup Language File |
| .XHTML | Extensible HyperText Markup Language File |
| .XHTML | Libxml HTML File |
| .XI | eXtended Instrument |
| .XI | ScreamTracker Instrument File |
| .XI | Fast Tracker 2 Instrument |
| .XIB | Interface Builder User Interface Resources (Apple Inc.) |
| .XIF | Wang Image File |
| .XIF | Xerox Image File |
| .XIF | LonMark Device Interface File (LonMark International) |
| .XIF | [Removed by request] [Removed by request] (ScanSoft, Inc.) |
| .XIF | Often a Fax Image (TIFF) File |
| .XIF | eXtended Image File Format |
| .XIF | [Removed by request] [Removed by request] (ScanSoft, Inc.) |
| .XIM | X11 Xim Toolkit Bitmap |
| .XIN | OmniMark Include File (Stilo) |
| .XIP | HP95 Execute-in-place Program |
| .XIP | Xbox Dashboard (Microsoft Corporation) |
| .XIP | Hotbar Image Compression Format (Skin) (Zango) |
| .XIX | IIS NNTP Subject Lists (Microsoft Corporation) |
| .XJS | WinExplorer Java Script |
| .XJT | Compressed GIMP Image with Properties of GIMP |
| .XJTGZ | Compressed GIMP Image with Properties of GIMP |
| .XJTZ2 | Compressed GIMP Image with Properties of GIMP |
| .XKS | IBM Softcopy Reader PDF Extended Bookshelf File (IBM) |
| .XL | XBLite Program File |
| .XL | Old Amiga Movie Format |
| .XL | Excel Spreadsheet (Microsoft Corporation) |
| .XL$ | Modem Bitware Fax Disk2 File |
| .XLA | Excel Add-in (Microsoft Corporation) |
| .XLA | Xlib Archive |
| .XLA | Data Import aka Dimport Translation Table (DATAIR Employee Benefit Systems, Inc.) |
| .XLAM | Excel Add-In (Microsoft Corporation) |
| .XLAMENX | egis Encrypted XLAM (Excel 2007) File (HiTRUST Inc.) |
| .XLAT | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XLB | Excel Worksheet (Microsoft Corporation) |
| .XLC | Excel Chart (Microsoft Corporation) |
| .XLD | Excel Dialog (Microsoft Corporation) |
| .XLE | Cooktop File |
| .XLF | Crystal Xcelsius Visualization (Business Objects SA) |
| .XLF | XLIFF Document |
| .XLG | Xnetech Engraving Logo File |
| .XLG | AutoCAD XREF Log (Autodesk, Inc.) |
| .XLK | Excel Backup (Microsoft Corporation) |
| .XLL | Excel Add-in (Microsoft Corporation) |
| .XLM | Excel Macro (Microsoft Corporation) |
| .XLNK | XML Link File (Tom Arn) |
| .XLO | Inventor Export Journal (Autodesk, Inc.) |
| .XLR | Works Spreadsheet or Chart (Microsoft Corporation) |
| .XLS | Works Spreadsheet (Microsoft Corporation) |
| .XLS | Excel Worksheet (Microsoft Corporation) |
| .XLSB | Excel Binary Workbook (Microsoft Corporation) |
| .XLSBENX | egis Encrypted XLSB (Excel 2007) File (HiTRUST Inc.) |
| .XLSENX | egis Encrypted Excel XLS File (HiTRUST Inc.) |
| .XLSHTML | Excel HTML Document (Microsoft Corporation) |
| .XLSM | Excel Macro-Enabled Workbook (Microsoft Corporation) |
| .XLSMENX | egis Encrypted XLSM (Excel 2007) File (HiTRUST Inc.) |
| .XLSMHTML | Excel Archived HTML Document (Microsoft Corporation) |
| .XLSX | Excel Microsoft Office Open XML Format Spreadsheet (Microsoft Corporation) |
| .XLSXENX | egis Encrypted Excel Open XML XLSX File (HiTRUST Inc.) |
| .XLSXENX | egis Encrypted XLSX (Excel 2007) File (HiTRUST Inc.) |
| .XLT | Procomm Plus Translation Table |
| .XLT | Lotus Translation Table (IBM) |
| .XLT | Excel Template (Microsoft Corporation) |
| .XLTHTML | Excel HTML Template (Microsoft Corporation) |
| .XLTM | Excel Macro-Enabled Template (Microsoft Corporation) |
| .XLTMENX | egis Encrypted XLTM (Excel 2007) File (HiTRUST Inc.) |
| .XLTX | Excel Template (Microsoft Corporation) |
| .XLTXENX | egis Encrypted XLTX (Excel 2007) File (HiTRUST Inc.) |
| .XLV | Excel VBA (Microsoft Corporation) |
| .XLW | Excel Workspace (Microsoft Corporation) |
| .XLX | XoloX Incomplete Download File |
| .XLXML | Excel XML Worksheet (Microsoft Corporation) |
| .XM | Fast Tracker 2 Extended Module |
| .XM2 | TextMap Ver. 2 Case Format File (LexisNexis) |
| .XMAP | File That Controls How XML/XSL Gets Served |
| .XMAS | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XMB | X-Wing Mission Briefing File |
| .XMC | Expression Media Catalog (Microsoft Corporation) |
| .XMCD | MathCAD XML-based Worksheet (Mathsoft Engineering & Education Inc.) |
| .XMCD | Xmcd CD Information (freedb.org) |
| .XMD | OmniMark Source Code (Stilo) |
| .XMD | GameJack Virtual CD or DVD Image (S.A.D. GmbH.) |
| .XMF | Milnta APL Transfer Function |
| .XMF | Extensible Music File Format (MIDI Manufacturers Association Incorporated) |
| .XMF | eXtensible Data Model and Format (XDMF) |
| .XMF | Mobile XMF File Format |
| .XMFG | MediaForge Runtime Player Distribution Project (XMLAuthor, Inc.) |
| .XMH | XMap Handheld Street Atlas USA Map and Route File (Delorme) |
| .XMI | XML Metadata Interchange Format |
| .XMI | EverQuest File |
| .XMI | Winamp Extended MIDI File |
| .XMI | XMill Compressed XML (Dan Suciu, AT&T Labs-Research and Hartmut Liefke, University of Pennsylvania) |
| .XMI | XMIT File Format (IBM) |
| .XMIT | XMIT File Format (IBM) |
| .XML | Extensible Markup Language File |
| .XMLBACKUP | EnABLE Backup File (Energy Scitech Ltd.) |
| .XMLS | Microsoft Excel 2003 Excel XML File (Microsoft Corporation) |
| .XMN | Expression Media Notepad (Microsoft Corporation) |
| .XMO | Authorware Movie Driver (Adobe Systems Incorporated) |
| .XMP | Spice Pspice Library File |
| .XMP | Adobe Extensible Metadata Platform (Adobe Systems Incorporated) |
| .XMP | Graphic File |
| .XMP | XMap Project Data (Delorme) |
| .XMPCF | TextMap Portable Case Format (LexisNexis) |
| .XMPSES | Premiere Elements DVD Marker File (Adobe Systems Incorporated) |
| .XMPTF | TextMap Portable Transcript Format (LexisNexis) |
| .XMS | ViewCafT XML Markup Session |
| .XMS | AutoCAD External Message (Autodesk, Inc.) |
| .XMS | RapidCaption Script (PeopleSupport, Inc.) |
| .XMS | XMS-Tracker |
| .XMT_TXT | Parasolid CAD File |
| .XMV | Milnta APL Transfer Function |
| .XMX | AutoCAD External Message Compiled File (Autodesk, Inc.) |
| .XMX | Character Set File |
| .XMXP | Help & Manual Uncompressed XML Project (EC Software GmbH) |
| .XMZ | Fasttracker 2/Extended Module |
| .XMZ | SofTeach Secure Exam File (ExamSoft Worldwide) |
| .XMZ | MegaView XGL Movie |
| .XNB | XNA Game Studio Express XNA Framework Content Pipeline Binary File (Microsoft Corporation) |
| .XNF | Standard Network File Form |
| .XNG | FishXing Culvert Data File (Stream Systems Technology Center, USDA Forest Service) |
| .XNG | OM2 911 Xchange Version 6 Document |
| .XNK | Exchange Shortcut (Microsoft Corporation) |
| .XNML | NML Language Language Extension (NevoSoft) |
| .XNT | Spice Pspice Library File |
| .XNT | W32/Sober-AD |
| .XOF | RenderMorphics |
| .XOI | eZediaMX and eZedia Player Locked Presentation Document |
| .XOM | OmniMark Source Code (Stilo) |
| .XOS | Xaos Tools Bitmap Image |
| .XOT | Xnetech Job Output File |
| .XOV | Rapidform XOV 3D Inspection/Model File (INUS Technology, Inc) |
| .XP | System Utility File |
| .XP3 | TVP (Kirikiri) XPK3 Virtual File System (kikyou.info) |
| .XPA | SoniqSync Extended Playlist (SoniqCast, LLC) |
| .XPA | Xpandata DB Transfer Encrypted Compressed File |
| .XPADDERCONTROLLER | Xpadder Controller Layout (Xpadder Team) |
| .XPB | XPB! Basic Source Code (Tony D. Jones) |
| .XPC | ActionReplay Saved Code (Datel Design and Development Ltd.) |
| .XPD | Playstation Download Instruction (DRM) File (Sony Corporation of America) |
| .XPF | X-Protector Project (The Xprotector Team) |
| .XPF | XaoS Position File (Jan Hubicka, Thomas Marsh, Zoltan Kovacs and Others) |
| .XPI | Mozilla/Firefox Browser Extension Archive (Mozilla) |
| .XPIX | Nonogram Puzzle |
| .XPJ | Micro Planner X-Pert Project Data File (Micro Planning International Inc.) |
| .XPK | XPK Player Compressed Audio (Data Becker) |
| .XPK | Spice Pspice Library File |
| .XPK | Xscript Package (Codec Games) |
| .XPL | Xset Plug-ins File |
| .XPL | X-Plane Plug-In (The House of X-Plane) |
| .XPL | LCDStudio Configuration Playlist (LCDStudio.com) |
| .XPL | Music File |
| .XPL | WinExplorer Simple Script |
| .XPM | BMC Software Patrol UNIX Icon File |
| .XPM | DESQview Macro (Symantec Corporation) |
| .XPM | X Pixmap Graphic |
| .XPO | Omega Research ProSuite |
| .XPO | Expo Product Tours Project (InstallShield Software Corporation) |
| .XPO | X-port Version 1 |
| .XPP | xCOMPOSER.pro Multimedia Data File |
| .XPR | Expression 3 Graphic File (Creature House Ltd.) |
| .XPR | exPresset CD Label (Pressit) |
| .XPR | XBMCTex/Xbox Media Center Graphic File (XboxMediaCenter Project) |
| .XPS | MonkeyJam Exposure Sheet (David Perry) |
| .XPS | XML Paper Specification (Microsoft Corporation) |
| .XPS | X-port Version 2 |
| .XPT | Dungeons & Dragons Core Rules 2 (Wizards of the Coast, Inc.) |
| .XPT | SAS Transport (XPORT) Format |
| .XPT | XPCOM Type Library |
| .XPT | eXact Packager Models (Giunti Interactive Labs S.r.l. (a company of Giunti Publising Group)) |
| .XPTHEME | Winstyles Theme (Stardock Corporation, Inc.) |
| .XPTOC | XDIME Player Table of Contents (Volantis Systems Ltd.) |
| .XPW | Accessible FormNet Fillable Form (Intercon Associates Inc.) |
| .XPW | Leading Market Technologies EXPO |
| .XPX | XML Format File |
| .XPX | Dungeons & Dragons Core Rules 2 with Expansion (Wizards of the Coast, Inc.) |
| .XPX | RAFTS-XP Macro File (XP Software Inc.) |
| .XPY | xpy Settings File (Jan T. Sott) |
| .XPY | MarketBrowser |
| .XQL | XML Query Language (XQL) (World Wide Web Consortium) |
| .XQT | SuperCalc Macro Sheet |
| .XQT | Waffle Executable File |
| .XR | Chaos Desktop External Reference File (Chaos systems AB) |
| .XR | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XR1 | Epic MegaGames Xargon File |
| .XRC | wxWidgets wxPython Resource File |
| .XREF | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XREF | AIX Cross Reference File |
| .XRF | TrialDirector Cross Reference File (inData Corporation) |
| .XRF | Crossreference File |
| .XRF | Cross Reference |
| .XRG | Xscript Game Registry (Codec Games) |
| .XRL | OSCAR Rules File |
| .XRL | Rapidform XOR/XOS 3D Scan Data & CAD File (INUS Technology, Inc) |
| .XRL | PowerDesigner Report (Sybase, Inc.) |
| .XRM-MS | Microsoft Security Certificate (Microsoft Corporation) |
| .XRP | RationalPlan Project File (Stand By Soft) |
| .XRP | Experior Practice Management Report (Experior Corporation) |
| .XRS | Realplayer Plug-in External Resources File (Real) |
| .XRT | Revolution EDX Spectrum Export File in Xraytor Format (4pi Analysis, Inc.) |
| .XRW | Architag XRay XML Editor |
| .XRX | Expression Encoder Media Profile Settings (Microsoft Corporation) |
| .XS | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XS | Hummingbird Exceed File |
| .xs | Perl xsub File Produced by h2xs |
| .XS3 | XESS Worksheet (Applied Information Systems, Inc.) |
| .XS4 | XESS Worksheet (Applied Information Systems, Inc.) |
| .XS5 | XESS Worksheet (Applied Information Systems, Inc.) |
| .XS8 | SIMUL8 |
| .XSA | XSA Raw Disk Image (XelaSoft) |
| .XSB | Sokoban++ Level File |
| .XSC | Transcribe! Transcription Document (Seventh String Software) |
| .XSC | XVI32 Script File (Christian Maas) |
| .XSC | XML Schema |
| .XSC | Xscript Script (Codec Games) |
| .XSD | XML Schema |
| .XSEND | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XSF | Milnta APL Transfer Function |
| .XSI | Softimage XSI 3D Model (Avid Technology, Inc.) |
| .XSL | FileMaker Database Design Report Template |
| .XSL | XML Stylesheet |
| .XSL | Steuer2001 File |
| .XSLT | XSL Transform File |
| .XSM | LEXIS-NEXIS Tracker |
| .XSN | xyALGEBRA File |
| .XSN | InfoPath Dynamic Form/Template (Microsoft Corporation) |
| .XSO | Expresso Project File (Ultrapico) |
| .XSP | Cross Stitch Professional Design File (DP Software) |
| .XSPF | XSPF Playlist (Xiph.Org Foundation) |
| .XSQL | Oracle XSQL Servlet XSQL Template File (Oracle Corporation) |
| .XSR | GEOPAK XS-List Report (Bentley Systems, Incorporated) |
| .XSS | Cross Stitch Professional Design File (DP Software) |
| .XSS | Ability Office Spreadsheet (Ability Software) |
| .XST | Easy Cross Cross Stitch Design (DOS Version) (Fulford Software Solutions) |
| .XST | X-Tract XML Script (DecisionSoft Limited) |
| .XSTEP | XStep DWI Maker File |
| .XSU | Fortran Libf77 File |
| .XSUM | Clapack File |
| .XSW | Milnta APL Transfer Function |
| .XSWRITER | TechWriter for XML Schemas Document (Adivo Ltd.) |
| .XT | FastTracker Music Track |
| .XT* | Crosstalk Related File |
| .XTB | LocoScript External Translation Table (LocoScript Software) |
| .XTC | XTrkCAD Project |
| .XTC | XTrkCAD Project (with Remarks) |
| .XTD | XML Type Definition |
| .XTEL | Xtelplot File Format |
| .XTG | QuarkXPress Tags File (Quark, Inc.) |
| .XTM | CmapTools Exported Topic Map (IHMC) |
| .XTML | XML4web Virtual HTML File (Altair Communications Corporation) |
| .XTODVD | ConvertXtoDVD Project File (VSO-Software) |
| .XTP | XTrkCAD Parameters |
| .XTP | XTrkCAD Demo (with Remarks) |
| .XTP | XTree Data File |
| .XTP | XTrkCAD Demo |
| .XTP | XTreeGold Overlay |
| .XTR | RealArcade Compressed Data File |
| .XTS | Babya Desktop Shell System Software Extension |
| .XTS | CSPro File |
| .XTX | xText Source File (Flambeaux Software) |
| .XUF | Milnta APL Transfer Function |
| .XUL | XML User Interface Language (Mozilla) |
| .XUM | Excel CAPE-OPEN Unit Operation Excel Unit-operation Model (AmsterCHEM) |
| .XUW | Milnta APL Transfer Function |
| .XV | Khoros Visualization Image File |
| .XVB | WinExplorer VB Script |
| .XVC | Verge Compiled Game Code (VERGE Co Ltd) |
| .XVF | Xyngo Video Board Media File (Xyngo AG) |
| .XVG | GROMACS Output File |
| .XVID | XviD CODEC |
| .XVM | VMware Virtual Machine Console (VMware, Inc.) |
| .XVO | ratDVD Internal File (RatDVD - Canada) |
| .XVP | Xview Package File |
| .XVS | Xview Scene Package File |
| .XVU | BOClean Database File |
| .XWB | Xbox Wavebank Audio Data (Microsoft Corporation) |
| .XWC | Crosstalk for Windows Compiled Script |
| .XWD | X Windows Dump |
| .XWD | Crossdown Puzzle File (Crossdown) |
| .XWF | Declan Software Word File (Declan Software) |
| .XWF | Yamaha XG Works File (Yamaha Corporation of America) |
| .XWI | X-Wing Mission File |
| .XWK | Crosstalk Keyboard Mapping |
| .XWP | XMLwriter XML Editor Project File (Wattle Software) |
| .XWP | Xerox Writer Text File |
| .XWP | Crosstalk Session |
| .XWP | Crosstalk for Windows Phone book |
| .XWS | Crosstalk for Windows Script |
| .XWS | Xara Webstyle File (Xara) |
| .XWV | Reason Malström Synth Instrument Patch (Propellerhead Software) |
| .XWZ | Xset Wizards File |
| .XWZ_1 | Xteq X-Setup File |
| .XX | Xxencoded File |
| .XX | Arcedit Temporary File |
| .XXA | Brixx Planner Account Detail Chart (Brixx Solutions Ltd.) |
| .XXD | Brixx Planner Calendar File (Brixx Solutions Ltd.) |
| .XXE | Xxencoded File |
| .XXG | Brixx Planner Graph (Brixx Solutions Ltd.) |
| .XXI | GameSpy Arcade (IGN Entertainment, Inc.) |
| .XXL | Archive |
| .XXN | Dimenzo Text Editor Text Document (Dimenzo, Inc.) |
| .XXP | Brixx Planner Plan File (Brixx Solutions Ltd.) |
| .XXR | Brixx Planner Report File (Brixx Solutions Ltd.) |
| .XXS | Sorenson Squeeze Settings File (Sorenson Media, Inc.) |
| .XXT | Extension DLL |
| .XXX | Paint Shop Photo Album Panorama (Corel Corporation) |
| .XXX | Compucon/Singer PSW Embroidery Design File |
| .XXX | Controlware VJ400 Digital CCTV Recording |
| .XXXX | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XXXXXX | allTunes Partial Download (Mediaservices, Inc.) |
| .XXY | SPARC Executable Script File |
| .XY | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| .XY | XYWrite Text File |
| .XY3 | XYWrite Text File |
| .XY4 | XYWrite IV Document |
| .XY4V | XYWrite IV document |
| .XYD | XYPad 2D CAD File (Coopware) |
| .XYP | XYWrite III Plus Document |
| .XYS | XYplorer Script (Donald Lessau) |
| .XYW | XYWrite Windows 4.0 Document |
| .XYZ | XMol XYZ |
| .XYZ | MDL Molfile Co-ordinate Animation Format (MDL Information Systems, Inc.) |
| .XYZ | Förderdiagnose Data File (Bettinger Software) |
| .XYZ | RPG Maker Graphic Format (Enterbrain, Inc.) |
| .XYZ | XYZZLY Plug-In for RealPlayer |
| .XYZ | Graph Coordinates |
| .XYZI | 3rdTech Scanner File |
| .XYZRGB | XYZ RGB Graphic (XYZ RGB Inc.) |
| .XZ | XZ Utils Compressed Archive |
| .XZP | XZP Container Format |
| .X_B | Parasolid CAD File |
| .X_T | Parasolid CAD File (UGS Corp.) |