| .X01 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .X02 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .X05 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .X06 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .X09 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .X1 | X1 Technologies | Arquivos de dados | X1 Desktop Search Saved Search Data | X1 | X1 Technologies |
| .X16 | Macromedia | Arquivos de dados | Macromedia Extra Document | Adobe Dreamweaver | Adobe Systems Incorporated |
| .X1D | Vicon Motion Systems Ltd | Arquivos de dados | Vicon Unprocessed Data | Vicon Nexus | Vicon Motion Systems Ltd |
| .X1S | X1 Technologies | Arquivos de dados | X1 Desktop Search Saved Search Data | X1 | X1 Technologies |
| .X1Z | X1 Technologies | Arquivos de dados | X1 Saved Search Archive | X1 | X1 Technologies |
| .X5 | Rockwell Automation Inc. | Arquivos de dados | Rockwell Software Logix 5 File | RSLogix 5 | Rockwell Automation Inc. |
| .X50 | Jeffrey C. Johnson | Arquivos de dados | XTreeGold Help Data | XTree | Jeffrey C. Johnson |
| .XAC | Tilted Mill Entertainment | Arquivos de dados | SimCity Societies Game File | SimCity Societies | Tilted Mill Entertainment |
| .XBC | SMART Technologies | Arquivos de dados | SMART Notebook File | MimioStudio | Mimio |
| .XBD | Xerox | Arquivos de dados | DocuWorks Binder File | DocuWorks Viewer Light | Fuji Xerox |
| .XBIN | Macecraft Software | Arquivos de dados | RegSupreme License Data | RegSupreme | Macecraft Software |
| .XBK | SMART Technologies | Arquivos de dados | SMART Notebook File | MimioStudio | Mimio |
| .XBT | SMART Technologies | Arquivos de dados | SMART Notebook Template File | SMART Technologies Notebook | SMART Technologies |
| .XCD | NetLabs | Arquivos de dados | WarpIN Data File | WarpIn | NetLabs |
| .XCH | Link-Assistant.com | Arquivos de dados | LinkAssistant Project | LinkAssistant | Link-Assistant.com |
| .XCK | Unknown Developer | Arquivos de dados | Extended Crack File | Unknown Software | Unknown Developer |
| .XCN | Broad Institute | Arquivos de dados | GenePattern XCN Data File | GenePattern | Broad Institute |
| .XCO | Xilinx, Inc. | Arquivos de dados | Xilinx CORE Generator Log | Xilinx CORE Generator System | Xilinx, Inc. |
| .XD | Unknown Developer | Arquivos de dados | CCS-lib.2 Examples Motif-CC File | Unknown Software | Unknown Developer |
| .XDB | Symantec Corporation | Arquivos de dados | Symantec Virus Database File | Symantec EndPoint Protection 12 | Symantec Corporation |
| .XDF | NASA | Arquivos de dados | Extended Disk Format Image | OS/2 | IBM |
| .XDP | Adobe Systems Incorporated | Arquivos de dados | XML Data Package | Adobe Acrobat DC | Adobe Systems Incorporated |
| .XDR_TOR | Accelrys Software Inc. | Arquivos de dados | Insight II Binary Torsion File | Insight II | Accelrys Software Inc. |
| .XDS | Nintendo | Arquivos de dados | DS Game Maker Project File | Invisionsoft DS Game Maker | Nintendo |
| .XDT | Olivier F5MZN | Arquivos de dados | Win-Test Extra Data | Win-Test | Olivier F5MZN |
| .XED | Unknown Developer | Arquivos de dados | XED Chemical Modeler Input/Output Data | Unknown Software | Unknown Developer |
| .XEF | X-Genics Limited | Arquivos de dados | eManager Form Data | X-Genics eManager | X-Genics Limited |
| .XEM | X-Genics Limited | Arquivos de dados | eManager Metered Units | X-Genics eManager | X-Genics Limited |
| .XEN | Activision | Arquivos de dados | Guitar Hero 3 Data File | Guitar Hero 3 | Neversoft |
| .XER | Oracle Corporation | Arquivos de dados | Primavera Project Management Proprietary Exchange Format | Primavera | Oracle Corporation |
| .XFC | Blacksun Software | Arquivos de dados | X-Fonter Font Collection | X-Fonter | Blacksun Software |
| .XFD | JetForm | Arquivos de dados | FormFlow 99 Form Data File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .XFDF | Adobe Systems Incorporated | Arquivos de dados | Adobe Acrobat XFDF File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .XFI | Leslie Lamport | Arquivos de dados | Latex Figures File | LaTex | Leslie Lamport |
| .XFO | Syncro Soft | Arquivos de dados | XSL-FO Formatted Form | Software602 602XML Form Filler | Software602 |
| .XFR | TIBCO Software Inc | Arquivos de dados | iProcess Process Definition File | TIBCO iProcess Suite | Xmarter |
| .XFT | Cay Horstmann | Arquivos de dados | ChiWriter Printer Font | ChiWriter | Cay Horstmann |
| .XG0 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .XG1 | Corel Corporation | Arquivos de dados | Corel Paradox Secondary Index | Corel WordPerfect X8 | Corel |
| .XG5 | Corel | Arquivos de dados | Corel Paradox Secondary Index Data File | Corel Paradox | Corel |
| .XGM | Metaphoric Software | Arquivos de dados | Techno Toys XG-909 MIDI Drum Machine File | XG-909 | Metaphoric Software |
| .XGO | GeoConcept SA | Arquivos de dados | GeoConcept Add-on | GeoConcept | GeoConcept SA |
| .XGP | Open Source | Arquivos de dados | Xfire Game Patcher File | XGP | Open Source |
| .XIP | Apple | Arquivos de dados | MacOS Signed Archive | Apple Archive Utility | Apple |
| .XIX | Microsoft Corporation | Arquivos de dados | IIS NNTP Subject Lists | Microsoft Internet Information Services (IIS) | Microsoft Corporation |
| .XKM | Open Source | Arquivos de dados | X KeyBoard File | Linux | Open Source |
| .XLC | Microsoft Corporation | Arquivos de dados | Excel Chart | Microsoft Excel | Microsoft Corporation |
| .XLF | Open Source | Arquivos de dados | XLIFF Document | Apple TextEdit | Apple |
| .XLG | Autodesk, Inc. | Arquivos de dados | AutoCAD External Reference Log | Autodesk AutoCAD | Autodesk, Inc. |
| .XLGC | Prosystech | Arquivos de dados | ExpressK Database File | Prosystech ExpressK | Prosystech |
| .XLO | Autodesk, Inc. | Arquivos de dados | Autodesk Inventor Export Journal Data | Autodesk Inventor | Autodesk, Inc. |
| .XLT | Microsoft Corporation | Arquivos de dados | Excel Template File | Microsoft Excel | Microsoft Corporation |
| .XLW | Microsoft Corporation | Arquivos de dados | Microsoft Excel Workspace | Microsoft Excel | Microsoft Corporation |
| .XLZ | CPT | Arquivos de dados | Crossword Power Tools Crossword Library File | Crossword Power Tools | CPT |
| .XM3 | Examiner Corporation | Arquivos de dados | Examiner Corporation Assessment Item Bank | Examiner System | Examiner Corporation |
| .XMAP | XMind | Arquivos de dados | XMind 2007/2008 Workbook | XMind | XMind |
| .XMAS | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .XMCD | Parametric Technology Corporation | Arquivos de dados | Mathcad Worksheet File | PTC Mathcad Prime | PTC |
| .XMD | Bitdefender | Arquivos de dados | Bitdefender Plugin File | Bitdefender Total Security 2018 | Bitdefender |
| .XMEF | LexisNexis | Arquivos de dados | TextMap Evidence Format File | TextMap | LexisNexis |
| .XMI | Object Management Group (OMG) | Arquivos de dados | XML Metadata Interchange File | Eclipse IDE for Java Developers | The Eclipse Foundation |
| .XMIT | IBM | Arquivos de dados | IBM XMIT Data | Unknown Software | Unknown Developer |
| .XML | Wattle Software | Arquivos de dados | XML File | MacroMates TextMate | MacroMates |
| .XMN | Sergei Andrzeevsky | Arquivos de dados | Sprintometer Document | Sprintometer Pro | Sergei Andrzeevsky |
| .XMP | Adobe Systems Incorporated | Arquivos de dados | Extensible Metadata Platform File | Microsoft Notepad | Microsoft Corporation |
| .XMPSES | Adobe Systems Incorporated | Arquivos de dados | Adobe Premiere Elements Data | Adobe Premiere Elements | Adobe Systems Incorporated |
| .XMS | Alexander Gross | Arquivos de dados | Music Studio Project | Alexander Gross Music Studio | Alexander Gross |
| .XMX | Autodesk, Inc. | Arquivos de dados | AutoCAD External Message Compiled Data | Autodesk AutoCAD | Autodesk, Inc. |
| .XMZ | Starbreeze Studios | Arquivos de dados | FastTracker 2 Extended Module | ModPlug Player | Open Source |
| .XNV | PeopleSoft | Arquivos de dados | nVision Layout File | PS/nVision | PeopleSoft |
| .XPB | Tony D. Jones | Arquivos de dados | XPB! Basic Source Code | XPB! Basic | Tony D. Jones |
| .XPF | Open Source | Arquivos de dados | Linux MultiMedia Studio Preset File | LMMS | Open Source |
| .XPJ | Adobe Systems Incorporated | Arquivos de dados | RoboHelp HTML Project | Adobe RoboHelp | Adobe Systems Incorporated |
| .XPK | THQ Nordic | Arquivos de dados | WWE RAW Model File | Cygnus Hex Editor | SoftCircuits |
| .XPM | XnSoft | Arquivos de dados | X11 Pixmap Graphic | GIMP | The GIMP Development Team |
| .XPO | Microsoft Corporation | Arquivos de dados | Microsoft Dynamics AX Export File | Microsoft Dynamics AX | Microsoft Corporation |
| .XPR | Parametric Technology Corporation | Arquivos de dados | Pro/ENGINEER Part Instance Accelerator File | Dassault Systemes SolidWorks | Dassault Systèmes |
| .XPS | Microsoft Corporation | Arquivos de dados | Microsoft XPS (XML Paper Specification) File | Nuance Power PDF Professional | Nuance |
| .XPT | Mozilla | Arquivos de dados | Mozilla Firefox Component | Mozilla Firefox | Mozilla |
| .XPW | Intercon Associates | Arquivos de dados | Accessible FormNet Fillable Form File | Accessible FormNet | Intercon Associates |
| .XPX | Intercon Associates | Arquivos de dados | Intercon FormNet File | Accessible FormNet | Intercon Associates |
| .XR2 | Open Source | Arquivos de dados | Xrecode II Registration | Xrecode | Open Source |
| .XRB | XMind | Arquivos de dados | XMind Resource Bundle | XMind | XMind |
| .XRDML | PANalytical | Arquivos de dados | XRDML Data File | Panalytical Data Collector | Malvern Instruments Ltd |
| .XREF | IBM | Arquivos de dados | IBM AIX Cross-Reference Data | IBM AIX | IBM |
| .XRF | Open Source | Arquivos de dados | Cal3D XML Materials File | Cal3DViewer | Open Source |
| .XRFF | University of Waikato | Arquivos de dados | Extensible Attribute-Relation File Format | Weka | University of Waikato |
| .XRL | SAP | Arquivos de dados | PowerDesigner Report File | Sybase PowerDesigner | SAP |
| .XRP | Stand By Soft | Arquivos de dados | RationalPlan Project File | Stand By Soft RationalPlan | RationalPlan |
| .XRT | 4pi Analysis | Arquivos de dados | EDX Spectrum Export File In Xraytor Format | RevolutionSEM | 4pi Analysis |
| .XRY | MSAB | Arquivos de dados | XRY Data File | XRY | MSAB |
| .XSC | Microsoft Corporation | Arquivos de dados | Visual Studio Dataset Internal Info File | Microsoft Visual Studio | Microsoft Corporation |
| .XSEND | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .XSF | Microsoft Corporation | Arquivos de dados | InfoPath Form Definition File | Microsoft InfoPath | Microsoft Corporation |
| .XSL | Syncro Soft | Arquivos de dados | XML eXtensible Stylesheet | Microsoft Notepad | Microsoft Corporation |
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