| .SOW | Interplay Entertainment | File di giochi | Descent ARJ Archive | Smith Micro StuffIt Deluxe | Smith Micro Software |
| .SP2 | Amusement Vision (SEGA) | File di giochi | Super Ball 2 Level File | Super Ball 2 | Unknown Developer |
| .SP4 | Solutions Etcetera | File di giochi | SuperCard 4 Player Project | Solutions Etcetera SuperCard | Solutions Etcetera |
| .SPA | Yu Higuchi | File di giochi | MikuMikuDance Sphere Mapping File | MikuMikuDance | Yu Higuchi |
| .SPB | Samsung Electronics | File di giochi | Samsung Kies Phonebook File | Samsung Kies | Samsung Electronics |
| .SPC | Various Developers | File di giochi | Software Publisher Certificate File | OpenSSL | Open Source |
| .SPK | Atari Corporation | File di giochi | Deer Hunter Map File | Deer Hunter | Sunstorm Interactive, Inc. |
| .SPL | Microsoft Corporation | File di giochi | Windows Print Spool File | Microsoft Windows | Microsoft Corporation |
| .SPO | Electronic Arts | File di giochi | Spore Saved Game | Electronic Arts Spore | Electronic Arts |
| .SPRITE | MIT Media Lab | File di giochi | Scratch Sprite File | MIT Scratch | MIT Media Lab |
| .SPS | IBM | File di giochi | SPSS Program File | IBM SPSS | IBM |
| .SPT | Interactive Data Visualization, Inc. | File di giochi | SpeedTree Tree Data File | SpeedTree Architect | Interactive Data Visualization, Inc. |
| .SQF | Bohemia Interactive | File di giochi | ArmA Script File | ArmA: Armed Assault | Bohemia Interactive |
| .SQM | Microsoft Corporation | File di giochi | Service Quality Monitoring File | Microsoft Windows | Microsoft Corporation |
| .SQS | Bohemia Interactive | File di giochi | Operation FlashPoint Script | Operation FlashPoint | Bohemia Interactive |
| .SRG | Ketron | File di giochi | Ketron Single Registration File | Ketron Software | Ketron |
| .SRM | Nintendo | File di giochi | Super Nintendo ROM Save File | Snes9x | Snes9x Team |
| .SS | Open Source | File di giochi | SilverStripe Source Code File | SilverStripe | Open Source |
| .SSA | Open Source | File di giochi | Sub Station Alpha Subtitle File | VirtualDub | Open Source |
| .SSC | Microsoft Corporation | File di giochi | SourceSafe Status File | Microsoft Visual Studio | Microsoft Corporation |
| .SSFREC | McLeodGaming | File di giochi | Super Smash Flash Recording Data | Super Smash Flash | McLeodGaming |
| .SSL | Bethesda Softworks | File di giochi | Fallout Script | Fallout Script Editor | Jargo |
| .SSS | Stardock Corporation | File di giochi | WindowBlinds Substyle File | WindowBlinds | Stardock Corporation |
| .SST | Microsoft Corporation | File di giochi | Serialized Certificate Store File | Certificate Manager Tool | Microsoft Corporation |
| .SSV | Seavus | File di giochi | Seavus Secure Project File | Seavus Project Viewer | Seavus |
| .ST3 | National Instruments | File di giochi | SPICE Status Data | Spice | National Instruments |
| .STA | Dassault Systèmes | File di giochi | ABAQUS Status File | ABAQUS software suite | Dassault Systèmes |
| .STG | Microsoft Corporation | File di giochi | ActiveSync Backup File | Microsoft ActiveSync | Microsoft Corporation |
| .STL | 3D Systems | File di giochi | Stereolithography File | Creo Parametric 3D Modeling Software | PTC |
| .STN | ON1, Inc. | File di giochi | Genuine Fractals Image | Adobe Photoshop | Adobe Systems Incorporated |
| .STO | Ecru Software | File di giochi | PRO100 3D Interior Design Project | Ecru Software PRO100 | Ecru Software |
| .STP | Unknown Developer | File di giochi | STEP 3D CAD File | CATIA | Dassault Systèmes |
| .STR | dBase, LLC | File di giochi | dBASE Structure List Object File | dBase | dBase, LLC |
| .STS | DuoS DSEMU | File di giochi | DuoS DSEMU Saved State File | DuoS DSEMU | Unknown Developer |
| .STUFF | CCP Games | File di giochi | EVE Online Data File | EVE Online | CCP Games |
| .SUB | URUWORKS | File di giochi | Subtitle File | CyberLink PowerDVD | CyberLink |
| .SUD | Aivosto Oy | File di giochi | Super Project Analyzer Data File | Super Project Analyzer | Aivosto Oy |
| .SV | Playsoft | File di giochi | Roland Garros Tennis File | Roland Garros Tennis Champions | Playsoft |
| .SV1 | Atari Corporation | File di giochi | RollerCoaster Tycoon Saved Game File | RollerCoaster Tycoon | Chris Sawyer |
| .SV4 | Chris Sawyer | File di giochi | RollerCoaster Tycoon Saved Game | RollerCoaster Tycoon | Chris Sawyer |
| .SV5 | Atari Corporation | File di giochi | Chris Sawyer's Locomotion Saved Game File | RollerCoaster Tycoon | Chris Sawyer |
| .SV6 | Chris Sawyer | File di giochi | RollerCoaster Tycoon 2 Saved Game | RollerCoaster Tycoon 2: Triple Thrill Pack | Chris Sawyer |
| .SV7 | Nintendo | File di giochi | Saved Game File | No Cash GBA (No$GBA) | Martin Korth |
| .SV8 | Atari Corporation | File di giochi | RollerCoaster Tycoon Game Data | RollerCoaster Tycoon | Chris Sawyer |
| .SVE | Simutrans Development Team | File di giochi | Simutrans Saved Game | Simutrans | Simutrans Development Team |
| .SVG | Nintendo | File di giochi | Saved Game File | No Cash GBA (No$GBA) | Martin Korth |
| .SVH | IEEE Xplore | File di giochi | SystemVerilog Source Code Header File | Microsoft Notepad | Microsoft Corporation |
| .SVS | Nintendo | File di giochi | Game Boy Advance Saved State File | Game Boy Advance | Nintendo |
| .SVT | Runic Games | File di giochi | Torchlight Saved Game File | TorchTools | Open Source |
| .SWC | Adobe Systems Incorporated | File di giochi | Flex Components Archive | Adobe Animate CC 2017 | Adobe Systems Incorporated |
| .SWE | Electronic Arts | File di giochi | NHL Ice Hockey 2002 Required Data | NHL 2002 | Electronic Arts |
| .SWV | Microsoft Corporation | File di giochi | Microsoft Sidewinder Game Voice Settings File | SideWinder Game Voice Utility | Microsoft Corporation |
| .SWW | Ubisoft | File di giochi | Anno Saved Game | ANNO 2070 | Ubisoft Blue Byte |
| .SXT | FMJ-Software | File di giochi | Propellerheads Reason 2 NN-XT Sound Data | FMJ-Software Awave Audio | FMJ-Software |
| .SYB | Microïds | File di giochi | Syberia II Game Archive File | Syberia II | Microïds |
| .SYN | Image-Line | File di giochi | SimSynth Document | FL Studio 12 | Image-Line |
| .SYSTEM | Open Source | File di giochi | Vega Strike Virtual System File | Microsoft Notepad | Microsoft Corporation |
| .SZS | Nintendo | File di giochi | Wii Game Data File | Wiimms SZS Toolset | Nintendo |
| .T3 | Michael J. Roberts | File di giochi | TADS 3 Game Data | TADS | Michael J. Roberts |
| .T3D | Epic Games | File di giochi | Unreal Engine 3D Object File | Unreal Tournament | Epic Games |
| .TAD | Cavedog | File di giochi | Total Annihilation Demo Saved Game Data | Total Annihilation | Cavedog |
| .TAF | Campbell Wild | File di giochi | ADRIFT Text Adventure File | ADRIFT Generator | Campbell Wild |
| .TAP | Various Developers | File di giochi | Commodore 64 Cassette Tape Image | Fuse | Open Source |
| .TAS | Campbell Wild | File di giochi | ADRIFT Text Adventure Saved Game | ADRIFT Generator | Campbell Wild |
| .TASP | Unknown Developer | File di giochi | Strategy Planner Data File | Tactical Assault Strategy Planner | Unknown Developer |
| .TBC | Psygnosis | File di giochi | Formula One 2001 Season 01 Vehicles Data | Formula One 2001 | Psygnosis |
| .TBI | Electronic Arts | File di giochi | FIFA 2001 Game Data | FIFA 2001 | EA Sports |
| .TBM | Nabi Studios | File di giochi | Toribash Mod File | Toribash | Nabi Studios |
| .TBV | Brain Innovation | File di giochi | Turbo-BrainVoyager Data File | Turbo-BrainVoyager | Brain Innovation |
| .TCM | IMSI/Design, LLC | File di giochi | TurboCAD Mac Drawing | IMSI TurboCAD Deluxe | Redway3d and others |
| .TCT | Adtollo | File di giochi | Topocad File | Topocad | Adtollo |
| .TD4 | Chris Sawyer | File di giochi | RollerCoaster Tycoon Track File | RollerCoaster Tycoon | Chris Sawyer |
| .TD6 | Chris Sawyer | File di giochi | RollerCoaster Tycoon 2 File | RollerCoaster Tycoon 2: Triple Thrill Pack | Chris Sawyer |
| .TDB | Google | File di giochi | Android Thumbnail Cache | Google Android | Google |
| .TDF | DVD Copy | File di giochi | Title Definition Format File | DVD X Copy | DVD Copy |
| .TDT | Sony | File di giochi | AVCHD Thumbnail File | Unknown Software | Unknown Developer |
| .TDX | D-TEG Security Co. | File di giochi | D-TEG CCTV Video Information File | D-TEG MRX PC Client | D-TEG Security Co. |
| .TER | Planetside Software | File di giochi | Terragen Terrain File | Planetside Software Terragen | Planetside Software |
| .TET | RM Education | File di giochi | Textease CT Template | Textease Studio | RM Education |
| .TF2 | Valve | File di giochi | Team Fortress 2 Data File | Team Fortress 2 | Valve |
| .TFR | LucasArts Entertainment Company, LLC | File di giochi | TIE Fighter Pilot File | Star Wars: TIE Fighter | LucasArts Entertainment Company, LLC |
| .TGH | Neversoft | File di giochi | Guitar Hero 3 Tier Settings File | Guitar Hero 3 | Neversoft |
| .TGI | Electronic Arts | File di giochi | SimCity 4 File | Electronic Arts SimCity 4 | Electronic Arts |
| .TGX | Firefly Studios | File di giochi | Stronghold Animated Data | Stronghold | Firefly Studios |
| .TI | timber-lang.org | File di giochi | Timber Compiler | Timber | timber-lang.org |
| .TIM | Sierra Entertainment | File di giochi | The Incredible Machine Level | The Incredible Machine | Sierra Entertainment |
| .TIS | Acronis | File di giochi | True Image Script | Acronis True Image | Acronis |
| .TIT | Microsoft Corporation | File di giochi | Train Simulator Track Interactive Table File | Microsoft Train Simulator | Kuju Entertainment |
| .TJA | TaikoJiro | File di giochi | Taikojiro Song Map File | Taikojiro | TaikoJiro |
| .TJC | TaikoJiro | File di giochi | Taikojiro Song Map Sequence File | Taikojiro | TaikoJiro |
| .TL_ | Spiele-Palast GmbH | File di giochi | Doko Game File | Doko | Spiele-Palast GmbH |
| .TML | Odetics Broadcast | File di giochi | AIRO Timeline File Format | AIRO | Odetics Broadcast |
| .TMR | Apimac | File di giochi | Apimac Timer Document | Apimac Timer | Apimac |
| .TNI | Sega | File di giochi | Sega Virtua Tennis Menufiles Common File | Virtua Tennis | Sega |
| .TOC | Sony | File di giochi | Sony PlayStation Portable (PSP) Audio File | Exact Audio Copy for PSP Edition | Interscape |
| .TOD | JVCKenwood Group | File di giochi | JVC Everio Video Capture File | VLC Media Player | VideoLAN |
| .TOR | LucasArts Entertainment Company, LLC | File di giochi | Star Wars: The Old Republic Asset File | StarWars | BioWare |
| .TOY | Ubisoft | File di giochi | Catz & Dogz Game File | Catz | Ubisoft |
| .TP4 | Chris Sawyer | File di giochi | RollerCoaster Tycoon Track Picture File | RollerCoaster Tycoon 3 | Frontier Developments plc |
| .TPJ | National Instruments | File di giochi | NI TestStand Project | NI TestStand | National Instruments |
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