| .D$$ | Interscape | File di giochi | AGT Game Encrypted Message File | AGiliTy | Open Source |
| .D02 | Cadence Design Systems | File di giochi | MicroSim PCBoard NC Drill Data File | OrCAD PCB Designer | Cadence Design Systems |
| .D03 | Interscape | File di giochi | Jydivide Split File | Jydivide | Interscape |
| .D2H | Blizzard Entertainment Inc. | File di giochi | Diablo II Hack It Module | Diablo II | Blizzard Entertainment Inc. |
| .D2I | Blizzard Entertainment Inc. | File di giochi | ATMA Diablo II | ATMA | Blizzard Entertainment Inc. |
| .D2R | Unknown Developer | File di giochi | Dazzle Dazzle Realization File | Dazzle Dazzle Realization | Unknown Developer |
| .D2S | Blizzard Entertainment Inc. | File di giochi | Diablo 2 Save File | Diablo II | Blizzard Entertainment Inc. |
| .D2X | Blizzard Entertainment Inc. | File di giochi | Diablo 2 Stash Data | Diablo II | Blizzard Entertainment Inc. |
| .D67 | Open Source | File di giochi | VICE Disk Image File | VICE | Open Source |
| .D81 | Commodore International | File di giochi | Commodore VC-1581 Diskette Emulator Image | VICE | Open Source |
| .DA2 | Microsoft Corporation | File di giochi | Windows Dancer File | Windows Media Center | Microsoft Corporation |
| .DA5 | Unknown Developer | File di giochi | AGT Game Data File | AGiliTy | Open Source |
| .DA6 | Unknown Developer | File di giochi | AGT Game Data File | AGiliTy | Open Source |
| .DA7 | MicroProse Software | File di giochi | Star Trek Generations Saved Game File | Star Trek Generations | MicroProse Software |
| .DAT | Unknown Developer | File di giochi | Game Data | Dragon UnPACKer | Open Source |
| .DATA | Appricon | File di giochi | Analysis Studio Offline Data | Microsoft Excel | Microsoft Corporation |
| .DAT_OLD | Mojang | File di giochi | Minecraft Level.dat Backup File | Minecraft | Mojang |
| .DAY | Groove Games | File di giochi | Day Of The Zombie Map File | Day of the Zombie | Groove Games |
| .DB | Dwayne Richard Hipp | File di giochi | Mobile Device Database File | SQLite | Dwayne Richard Hipp |
| .DB0 | dBase, LLC | File di giochi | dBASE Init File | dBase | dBase, LLC |
| .DB4 | dBase, LLC | File di giochi | dBASE IV Data | dBase | dBase, LLC |
| .DB5 | GSC Game World | File di giochi | S.T.A.L.K.E.R. Game Data | S.T.A.L.K.E.R.: Shadow of Chernobyl | GSC Game World |
| .DB6 | GSC Game World | File di giochi | S.T.A.L.K.E.R. Game File Format | S.T.A.L.K.E.R | GSC Game World |
| .DBA | PDC (Prolog Development Center) | File di giochi | Turbo Prolog Database | Visual Prolog | PDC (Prolog Development Center) |
| .DBB | GSC Game World | File di giochi | S.T.A.L.K.E.R. Game File | S.T.A.L.K.E.R | GSC Game World |
| .DBF | dBase, LLC | File di giochi | Database File | Microsoft Excel | Microsoft Corporation |
| .DBI | Electronic Arts | File di giochi | FIFA World Cup Game Data Comin Fe | FIFA Soccer 2002 | Electronic Arts |
| .DC6 | Blizzard Entertainment Inc. | File di giochi | Diablo 2 Static Image | Diablo II | Blizzard Entertainment Inc. |
| .DCC | Nokia | File di giochi | Nokia Dynamic Camera Configuration | Symbian OS | Nokia |
| .DCT | Microsoft Corporation | File di giochi | Dictionary File | QuarkXPress | Quark Software Inc. |
| .DCZ | BIGAL | File di giochi | DynaCAD CAD Document | DynaCAD | BIGAL |
| .DD2 | ProFantasy Software Ltd | File di giochi | Dungeon Designer 2 Map Design File | Dungeon Designer 2 | ProFantasy Software Ltd |
| .DDB | Avid Technology | File di giochi | Digidesign Database | Avid Pro Tools | Avid Technology |
| .DDO | Unknown Developer | File di giochi | Tank3D Game Data | Unknown Software | Unknown Developer |
| .DDPOKERSAV | Donohoe Digital LLC | File di giochi | DD Poker Save Game File | DD Poker | Donohoe Digital LLC |
| .DDT | Sports Interactive | File di giochi | Football Manager Keep Player Data File | Football Manager 2016 | Sports Interactive |
| .DEF | Microsoft Corporation | File di giochi | Module Definition File | Microsoft Visual Studio | Microsoft Corporation |
| .DEK | Wizards of the Coast | File di giochi | Magic: The Gathering Deck File | Magic | Interscape |
| .DEM | Valve | File di giochi | Video Game Demo File | VirtualDub | Open Source |
| .DEMO | Open Source | File di giochi | Pokemon Type Wild Data File | Pokémon Type Wild | Open Source |
| .DESC | Electronic Arts | File di giochi | Battlefield 2 Map Description File | Battlefield 2 | Electronic Arts |
| .DFC | Jenner Fusari | File di giochi | Defractor Instrument | Neurotix Defractor | Jenner Fusari |
| .DFS | Open Source | File di giochi | BrainSuite Surface File | BrainSuite | Open Source |
| .DGZ | Dave | File di giochi | Dega Saved State | Dega | Dave |
| .DIE | Blizzard Entertainment Inc. | File di giochi | Diablo Item File | Diablo | Blizzard Entertainment Inc. |
| .DIF | Microsoft Corporation | File di giochi | Data Interchange Format | Microsoft Excel | Microsoft Corporation |
| .DINERDASHS | PlayFirst | File di giochi | Dinerdash Saved Game File | Diner Dash | PlayFirst |
| .DJS | Electronic Arts | File di giochi | NASCAR Thunder 2004 Game Music File | NASCAR Thunder 2004 | Electronic Arts |
| .DKD | Interscape | File di giochi | Karaoke Music File | JBK Karaoke Player | Interscape |
| .DKX | Ellipse Studios | File di giochi | Submarine Titans Battle Map File | Submarine Titans | Ellipse Studios |
| .DL | Microsoft Corporation | File di giochi | Zoo Tycoon 2 Data File | Zoo Tycoon 2 | Microsoft Corporation |
| .DLG | Crytek | File di giochi | Crysis Dialogue Data File | Crysis | Crytek |
| .DM2 | Interscape | File di giochi | Toad Data Modeler 2 File | Toad Data Modeler | Interscape |
| .DM3 | Gatan | File di giochi | DigitalMicrograph Image | ImageJ | National Institutes of Health (NIH) |
| .DMAP | Open Source | File di giochi | Conquer Online 2 Game Map | Conquer Online 2 | Open Source |
| .DMB | BYOND | File di giochi | BYOND Game Executable | BYOND | BYOND |
| .DMO | Wouter van Oortmerssen | File di giochi | Cube 2: Sauerbraten Demo File | Cube 2 Sauerbraten | Open Source |
| .DN2 | Apogee Components | File di giochi | Duke Nukem Episode 2 Game File | Duke Nukem Episode 2: Mission Moonbase | Apogee Software, Ltd. |
| .DNF | 3D Realms | File di giochi | Duke Nukem Forever Map File | Duke Nukem Forever | 3D Realms |
| .DNI | MobyGames | File di giochi | RealMyst 3D Game Archive | realMyst 3D | MobyGames |
| .DNP | Apple | File di giochi | DRM Digital Rights Management Data | Apple QuickTime Player | Apple |
| .DNS | 3D Realms | File di giochi | Duke Nukem Forever Save File | Duke Nukem Forever | 3D Realms |
| .DOG | Ubisoft Blue Byte | File di giochi | Dogz Dog Description File | Petz | Ubisoft Blue Byte |
| .DOL | Nintendo | File di giochi | GameCube Executable File | Dolphin (emulator) | Dolphin Emulator Project |
| .DOR | Graphisoft | File di giochi | ArchiCAD Geometric Description Language File | ARCHICAD | Graphisoft |
| .DPC | Microsoft Corporation | File di giochi | Microsoft Office Resource File | Microsoft Office | Microsoft Corporation |
| .DPF | Open Source | File di giochi | Dargon Package | Dargon | Open Source |
| .DPM | Avid Technology | File di giochi | Pro Tools Plugin File | Avid Pro Tools | Avid Technology |
| .DS | DAZ 3D | File di giochi | DAZ Studio 1/2 Script | DAZ Studio | DAZ 3D |
| .DSG | Simon Howard (Fraggle) | File di giochi | Doom Saved Game | Chocolate Doom | Simon Howard (Fraggle) |
| .DSR | Activision | File di giochi | Modern Warfare 3 Dedicated Server Recipe File | Call of Duty 4: Modern Warfare | Activision |
| .DST | Autodesk, Inc. | File di giochi | AutoCAD Sheet Set File | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .DSV | Open Source | File di giochi | DeSmuME Saved Game File | DeSmuME | Open Source |
| .DT1 | National Geospatial-Intelligence Agency | File di giochi | DTED Level 1 File | ESRI ArcGIS for Desktop | ESRI (Environmental Systems Research Institute) |
| .DTI | Microsoft Corporation | File di giochi | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .DTM | Prodatron | File di giochi | DigiTrakker Audio Module | CocoModX | Open Source |
| .DUA | Electronic Arts | File di giochi | FIFA 2001 Game Data | FIFA 2001 | EA Sports |
| .DUC | Datel | File di giochi | Action Replay Max DS Save File | Unknown Software | Unknown Developer |
| .DUN | Trendy Entertainment | File di giochi | Dungeon Defenders Saved Game File | Trendy Entertainment Dungeon Defenders | Trendy Entertainment |
| .DWC | Emulex Corporation | File di giochi | Emulex DWC Firmware Update File | Emulex lputil | Emulex Corporation |
| .DWD | DiamondWare Ltd. | File di giochi | DiamondWare Digital Audio File | Wi-Fone | DiamondWare Ltd. |
| .DX | Digital Equipment Corporation | File di giochi | DEC WPS Plus File | Microsoft Notepad | Microsoft Corporation |
| .DXM | Ion Storm Inc. | File di giochi | Deus Ex Map File | Deus Ex: Game of the Year Edition | Ion Storm Inc. |
| .DXS | Eidos Interactive | File di giochi | Deus Ex Saved Game | Deus Ex: Game of the Year Edition | Ion Storm Inc. |
| .DXT | LucasArts Entertainment Company, LLC | File di giochi | LucasArts The Secret Of Monkey Island: Special Edition Texture | The Secret Of Monkey Island | LucasArts Entertainment Company, LLC |
| .DZ | Digital Extremes | File di giochi | Land Of The Dead Level File | Unreal Tournament | Epic Games |
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