| .SPZ | Crestron Electronics | Datatiedostot | Creston SIMPL Windows Compiled Program | SIMPL Windows | Crestron Electronics |
| .SQ | Calerga Sarl | Datatiedostot | Sysquake Program | Sysquake | Calerga Sarl |
| .SQ7 | Daktronics | Datatiedostot | Daktronics Venus 7000 Electronic Sign Sequence Data | Venus 7000 Sports Display Controller | Daktronics |
| .SQD | SparkPath Technologies | Datatiedostot | Configuration Settings File | SP Debugger for SQR | SparkPath Technologies |
| .SQF | Bohemia Interactive | Datatiedostot | ArmA Script File | ArmA: Armed Assault | Bohemia Interactive |
| .SQR | Oracle Corporation | Datatiedostot | SQL Program File | Microsoft SQL Server | Microsoft Corporation |
| .SQUASHFS | Open Source | Datatiedostot | Squashfs File System File | 7-Zip | Igor Pavlov |
| .SR2 | Sony | Datatiedostot | Sony RAW Image | Adobe Photoshop | Adobe Systems Incorporated |
| .SRB | Open Source | Datatiedostot | XWE File | XWE | Open Source |
| .SRD | Sage | Datatiedostot | Sage Report Data File | Sage Instant Accounts | Sage |
| .SRE | Microsoft Corporation | Datatiedostot | Windows CE 5.0 File | Microsoft Windows CE Embedded | Microsoft Corporation |
| .SRF | NewTek | Datatiedostot | LightWave Surface File | LightWave 3D | NewTek |
| .SRG | Ketron | Datatiedostot | Ketron Single Registration File | Ketron Software | Ketron |
| .SRH | BMC | Datatiedostot | BMC Remedy AR System Server Saved Search | Unknown Software | Unknown Developer |
| .SRL | Procedimientos-Uno, S.L. | Datatiedostot | Arquitienda Local Database File | CFwin | iMventa Ingenieros |
| .SRN | Micro Focus International plc | Datatiedostot | Micro Focus Screen | Micro Focus Extra! | Micro Focus International plc |
| .SRO | Unknown Developer | Datatiedostot | MADCOW Multi-Site ATIS Data Collection Working Group Data | MADCOW (Multi-Site ATIS Data Collection Working Group) | Interscape |
| .SRQ | Microsoft Corporation | Datatiedostot | Microsoft Windows Server Unprocessed Request File | Microsoft Windows Server 2016 | Microsoft Corporation |
| .SRT | SourceForge | Datatiedostot | SubRip Subtitle File | VLC Media Player | VideoLAN |
| .SRW | Samsung Electronics | Datatiedostot | Samsung RAW Image | ACD Systems ACDSee | ACD Systems |
| .SRX | Sublime HQ Pty Ltd | Datatiedostot | SPARQL Query Results XML Format Result | Microsoft Notepad | Microsoft Corporation |
| .SS2 | Unknown Developer | Datatiedostot | Terrasoft SAS Program File | Unknown Software | Unknown Developer |
| .SS4 | MODRATEC | Datatiedostot | SigScribe4 Design File | SigScribe 4 | MODRATEC |
| .SSC | Microsoft Corporation | Datatiedostot | SourceSafe Status File | Microsoft Visual Studio | Microsoft Corporation |
| .SSD | Stardock Corporation | Datatiedostot | WindowBlinds Skin File List | WindowBlinds | Stardock Corporation |
| .SSG | ICLUBcentral Inc. | Datatiedostot | Investor's Toolkit Stock Selection Guide | Investor's Toolkit | ICLUBcentral Inc. |
| .SSL | Bethesda Softworks | Datatiedostot | Fallout Script | Fallout Script Editor | Jargo |
| .SSM | RealNetworks | Datatiedostot | Standard Streaming Metafile | RealPlayer | Realtime Technologies |
| .SSN | Samsung Electronics | Datatiedostot | Samsung Kies Notes Backup | Samsung Kies | Samsung Electronics |
| .SSP | Scala | Datatiedostot | Scala Server Page | Scalate | Open Source |
| .SSS | Stardock Corporation | Datatiedostot | WindowBlinds Substyle File | WindowBlinds | Stardock Corporation |
| .SST | Microsoft Corporation | Datatiedostot | Serialized Certificate Store File | Certificate Manager Tool | Microsoft Corporation |
| .SSU | Microsoft Corporation | Datatiedostot | SMS Hierarchy Manager Site Update | Microsoft Systems Management Server | Microsoft Corporation |
| .SSV | Seavus | Datatiedostot | Seavus Secure Project File | Seavus Project Viewer | Seavus |
| .SSX | IBM | Datatiedostot | IBM Rational XDE Data | Rational XDE | IBM |
| .ST0 | National Instruments | Datatiedostot | SPICE Status Data | Spice | National Instruments |
| .ST1 | Converge Horizons | Datatiedostot | DigiTitle Master Subtitle File | DigiTitle Master | Converge Horizons |
| .ST2 | National Instruments | Datatiedostot | SPICE Status Data | Spice | National Instruments |
| .ST3 | National Instruments | Datatiedostot | SPICE Status Data | Spice | National Instruments |
| .ST4 | Corel Corporation | Datatiedostot | Pinnacle Studio 400 Project File | Pinnacle Studio | Corel |
| .ST6 | XnSoft | Datatiedostot | SBIG CCD Camera Image | XnView MP | XnSoft |
| .ST7 | XnSoft | Datatiedostot | SBIG CCD Camera Image | XnView MP | XnSoft |
| .ST9 | XnSoft | Datatiedostot | SBIG CCD Camera Image | XnView MP | XnSoft |
| .STA | Dassault Systèmes | Datatiedostot | ABAQUS Status File | ABAQUS software suite | Dassault Systèmes |
| .STACK | Apple | Datatiedostot | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .STAGE1 | Apple | Datatiedostot | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .STAR | Apple | Datatiedostot | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .STARTUP | Apple | Datatiedostot | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .STATE | Microsoft Corporation | Datatiedostot | Windows Photo Gallery User Data | Windows Photo Gallery | Microsoft Corporation |
| .STATS | Open Source | Datatiedostot | FreeSurfer Statistics File | FreeSurfer | Open Source |
| .STATUS | Open Source | Datatiedostot | UDraw(Graph) File | UDraw(Graph) | Open Source |
| .STC | Adobe Systems Incorporated | Datatiedostot | Contribute Connection Key File | Adobe Contribute 6.5 | Adobe Systems Incorporated |
| .STD | Oracle Corporation | Datatiedostot | Apache OpenOffice Drawing Template | Apache OpenOffice | Apache Software Foundation |
| .STDF | Teradyne | Datatiedostot | Standard Test Data Format | Unknown Software | Unknown Developer |
| .STEGANO | Unknown Developer | Datatiedostot | Steganographic Image File | Unknown Software | Unknown Developer |
| .STF | Microsoft Corporation | Datatiedostot | Exchange 2000 Server Temporary File | Microsoft Exchange Server | Microsoft Corporation |
| .STI | Oracle Corporation | Datatiedostot | StarOffice Presentation Template | Apache OpenOffice | Apache Software Foundation |
| .STK | Peter Bone | Datatiedostot | Stickfigure Animator File | Pivot Animator (Pivot Stickfigure Animator) | Peter Bone |
| .STKX | DTLink Software | Datatiedostot | Personal Stock Streamer Portfolio File | Personal Stock Streamer | DTLink Software |
| .STL | 3D Systems | Datatiedostot | Stereolithography File | Creo Parametric 3D Modeling Software | PTC |
| .STM | Microsoft Corporation | Datatiedostot | Exchange Streaming Media File | Microsoft Exchange Server | Microsoft Corporation |
| .STORAGE | Apple | Datatiedostot | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .STORY | Storyist Software | Datatiedostot | Storyist Document | Storyist | Storyist Software |
| .STP | Unknown Developer | Datatiedostot | STEP 3D CAD File | CATIA | Dassault Systèmes |
| .STR | dBase, LLC | Datatiedostot | dBASE Structure List Object File | dBase | dBase, LLC |
| .STRING | IDM Computer Solutions | Datatiedostot | UltraEdit Data | UltraEdit | IDM Computer Solutions |
| .STT | Microsoft Corporation | Datatiedostot | Streets & Trips Map Template | Microsoft AutoRoute | Microsoft Corporation |
| .STU | Avid Technology | Datatiedostot | Pinnacle Studio Project | Pinnacle Studio | Corel |
| .STV | Unknown Developer | Datatiedostot | SofTV Authoring Data | Unknown Software | Unknown Developer |
| .STVPROJ | Microsoft Corporation | Datatiedostot | Microsoft Visual Studio Data File | Microsoft Visual Studio | Microsoft Corporation |
| .STW | Oracle Corporation | Datatiedostot | StarOffice Document Template | Apache OpenOffice | Apache Software Foundation |
| .STX | Unknown Developer | Datatiedostot | Scream Tracker Music Interface Kit File | CocoModX | Open Source |
| .STY | Jørgen Sørensen / Jososoft | Datatiedostot | Yamaha/Korg Keyboard Style | Style Fixer | Jørgen Sørensen / Jososoft |
| .STYKZ | Sons of Thunder | Datatiedostot | Stykz Animation | Sons of Thunder Stykz | Sons of Thunder |
| .SUA | Naviter | Datatiedostot | SeeYou Airspace Data | SeeYou | Naviter |
| .SUC | Interscape | Datatiedostot | Hello Engines! 2.1 Data | Hello Engines | Interscape |
| .SUI | Sean Maxwell | Datatiedostot | StarSplatter User Interface File | StarSplatter User Interface | Sean Maxwell |
| .SUJ | Open Source | Datatiedostot | Stacker Unlimited Job | Stacker Unlimited | Open Source |
| .SUM | AmsterCHEM | Datatiedostot | Scilab Unit Operation Model File | AmsterCHEM MATLAB CAPE-OPEN Unit Operation | AmsterCHEM |
| .SUPP | Apple | Datatiedostot | iOS Data File | Apple iOS | Apple |
| .SUS | SAP | Datatiedostot | SAP Transactionware GM POS Xpress Suspended Data | SAP BusinessObjects Business Intelligence | SAP |
| .SVCLOG | Microsoft Corporation | Datatiedostot | Microsoft Visual Studio Diagnostics Data | Microsoft Visual Studio | Microsoft Corporation |
| .SVD | Polytec | Datatiedostot | Scanning Vibrometer Data File | Polytec PSV Software | Polytec |
| .SVF | Joint Test Action Group | Datatiedostot | Serial Vector Format File | MicroStation | Bentley Systems |
| .SVN | Apache Software Foundation | Datatiedostot | Subversion Data File | Subversion | Apache Software Foundation |
| .SVP | SwiftView, Inc. | Datatiedostot | SwiftView Command File | SwiftView | SwiftView, Inc. |
| .SVS | Nintendo | Datatiedostot | Game Boy Advance Saved State File | Game Boy Advance | Nintendo |
| .SW0 | National Instruments | Datatiedostot | SPICE Sweep Operations Output Data | Spice | National Instruments |
| .SWB | Adobe Systems Incorporated | Datatiedostot | Adobe Photoshop Data | Adobe Photoshop | Adobe Systems Incorporated |
| .SWG | Embarcadero Technologies | Datatiedostot | SWAG Pascal Snippets | Turbo Pascal | Embarcadero Technologies |
| .SWK | Avanquest Software | Datatiedostot | StudyWorks Save File | Studyworks! Teaching Pro: Mathematics Complete | Avanquest Software |
| .SWM | Microsoft Corporation | Datatiedostot | Split Windows Imaging Format File | Microsoft ImageX | Microsoft Corporation |
| .SWR | Unknown Developer | Datatiedostot | SageWorld Anti-Hacker Program File | Unknown Software | Unknown Developer |
| .SWS | TIBCO Software Inc | Datatiedostot | S-PLUS Workspace | TIBCO Spotfire S+ Products | TIBCO Software Inc |
| .SX | Dipl.-Phys.-Ing. Ralf Wirtz | Datatiedostot | SimplexNumerica Data File | SimplexNumerica | Dipl.-Phys.-Ing. Ralf Wirtz |
| .SXI | Oracle Corporation | Datatiedostot | StarOffice Impress Presentation | Apache OpenOffice | Apache Software Foundation |
| .SY1 | Daichi Laboratory | Datatiedostot | Synth 1 Patch File | Synth1 | Daichi Laboratory |
| .SY3 | Harvard Graphics | Datatiedostot | Harvard Graphics Symbol File | ACD Systems Canvas | Microsoft Corporation |
| .SYC | The Wireshark Team | Datatiedostot | Sniffer Capture File | Wireshark | The Wireshark Team |
| .SYF | SMC Corporation | Datatiedostot | SY Configurator Project | SY Configurator | SMC Corporation |
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