| .SAT | Spatial Corp | CAD-filer | ACIS SAT 3D Model File | Autodesk Fusion 360 | Autodesk, Inc. |
| .SBP | Autodesk, Inc. | Rasterbilledfiler | Sketchbook Express iCloud Image | SketchBook | Autodesk, Inc. |
| .SCH | Autodesk, Inc. | Datafiler | EAGLE Schematics File | Autodesk EAGLE | Autodesk, Inc. |
| .SDC | Stardock Corporation | Sikkerhedskopifiler | Stardock Central Download Archive | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .SDF | Microsoft Corporation | Databasefiler | SQL Server Compact Database File | AutoCAD Map 3D | Autodesk, Inc. |
| .SDK | Autodesk, Inc. | CAD-filer | AutoSketch Drawing | AutoSketch | Autodesk, Inc. |
| .SDL | Microsoft Corporation | Udviklerfiler | Service Description Language File | Infrastructure Map Server | Autodesk, Inc. |
| .SET | Xerox | Indstillingsfiler | Document Library Property Set File | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .SHP | Autodesk, Inc. | 3D-billedfiler | AutoCAD Shape File | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .SHX | Autodesk, Inc. | CAD-filer | AutoCAD Compiled Shape File | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .SI | Autodesk, Inc. | 3D-billedfiler | Softimage Image File | Autodesk Softimage 2015 | Autodesk, Inc. |
| .SKF | Autodesk, Inc. | CAD-filer | AutoSketch Drawing | AutoSketch | Autodesk, Inc. |
| .SKL | Autodesk, Inc. | 3D-billedfiler | Maya Skeleton File | Autodesk Maya | Autodesk, Inc. |
| .SLB | Autodesk, Inc. | Ikke Almindelige Filer | AutoCAD Slide Library | Autodesk AutoCAD | Autodesk, Inc. |
| .SLD | ESRI (Environmental Systems Research Institute) | GIS-filer | Styled Layer Descriptor | Autodesk AutoCAD | Autodesk, Inc. |
| .SLDASM | Dassault Systèmes | CAD-filer | SolidWorks Assembly File | Autodesk Fusion 360 | Autodesk, Inc. |
| .SLDPRT | Dassault Systèmes | CAD-filer | SolidWorks CAD Part File | Autodesk Fusion 360 | Autodesk, Inc. |
| .SLG | Dionex Corporation | Datafiler | Chromeleon Audit Trail Data | Autodesk AutoCAD | Autodesk, Inc. |
| .SLP | Magix Software GmbH | Lydfiler | SpectraLayers Pro Project | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .SMB | Autodesk, Inc. | Datafiler | Autodesk Symbol Library | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .SQLITE | Dwayne Richard Hipp | Databasefiler | SQLite Database File | AutoCAD Map 3D | Autodesk, Inc. |
| .SSC | Microsoft Corporation | Udviklerfiler | SourceSafe Status File | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .STB | Autodesk, Inc. | Indstillingsfiler | AutoCAD Plot Style Table File | Autodesk AutoCAD | Autodesk, Inc. |
| .STEP | Unknown Developer | 3D-billedfiler | STEP 3D Model | Autodesk Fusion 360 | Autodesk, Inc. |
| .STP | Unknown Developer | 3D-billedfiler | STEP 3D CAD File | Autodesk Fusion 360 | Autodesk, Inc. |
| .STYXML | Autodesk, Inc. | CAD-filer | Inventor Style Library File | Autodesk Inventor | Autodesk, Inc. |
| .SV$ | Autodesk, Inc. | Sikkerhedskopifiler | AutoCAD Automated Backup File | Autodesk AutoCAD | Autodesk, Inc. |
| .TBL | Blizzard Entertainment Inc. | Datafiler | StarCraft Information Table | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .TBP | Trimble Inc. | CAD-filer | Tekla BIMsight Project | Autodesk Topobase | Autodesk, Inc. |
| .TDF | DVD Copy | Indstillingsfiler | Title Definition Format File | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .TF | Borland | Indstillingsfiler | Turbo Profiler Configuration | Autodesk Inventor | Autodesk, Inc. |
| .TSK | Microsoft Corporation | Indstillingsfiler | Pocket PC Skin | Autodesk EAGLE | Autodesk, Inc. |
| .UG | Autodesk, Inc. | Vektorbilledfiler | Drawing File | AutoCAD for Mac | Autodesk, Inc. |
| .UNT | Autodesk, Inc. | Datafiler | AutoCAD Unit Definition Data File | Autodesk AutoCAD | Autodesk, Inc. |
| .USR | FileMaker Inc. | Databasefiler | FileMaker Pro Database File | CadSoft EAGLE | Autodesk, Inc. |
| .UVW | Autodesk, Inc. | Datafiler | UVW Coordinates File | Autodesk 3ds Max | Autodesk, Inc. |
| .VLX | Autodesk, Inc. | Eksekverbare filer | Compiled AutoLISP File | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .VRT | Superscape | Webfiler | Virtual World | Autodesk AutoCAD | Autodesk, Inc. |
| .VUE | E-on Software, Inc. | 3D-billedfiler | Vue Scene File | Autodesk 3ds Max | Autodesk, Inc. |
| .WAC | Wacom | Datafiler | Inkling Sketch XML File | SketchBook | Autodesk, Inc. |
| .WDP | Microsoft Corporation | Rasterbilledfiler | Windows Media Photo File | Autocad Electrical | Autodesk, Inc. |
| .WEA | Autodesk, Inc. | Datafiler | Ecotect Weather File | Ecotect Analysis | Autodesk, Inc. |
| .WPI | Wacom | Vektorbilledfiler | Inkling Sketch Binary File | SketchBook | Autodesk, Inc. |
| .XLG | Autodesk, Inc. | Datafiler | AutoCAD External Reference Log | Autodesk AutoCAD | Autodesk, Inc. |
| .XLO | Autodesk, Inc. | CAD-filer | Autodesk Inventor Export Journal Data | Autodesk Inventor | Autodesk, Inc. |
| .XMS | Alexander Gross | Indstillingsfiler | Music Studio Project | Autodesk AutoCAD | Autodesk, Inc. |
| .XMX | Autodesk, Inc. | Datafiler | AutoCAD External Message Compiled Data | Autodesk AutoCAD | Autodesk, Inc. |
| .XSI | Autodesk, Inc. | 3D-billedfiler | Softimage XSI 3D Image | Autodesk Softimage 2015 | Autodesk, Inc. |
| .XSP | Open Source | Lydfiler | Kodi Smart Playlist File | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .XTP | adnx | Datafiler | xTime Project Document | Autodesk AutoCAD Civil 3D | Autodesk, Inc. |
| .X_T | Siemens PLM Software | CAD-filer | Parasolid Model Part File | Autodesk Fusion 360 | Autodesk, Inc. |
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