| .DLY | Xilinx, Inc. | Pliki z danymi | Xilinx ISE ReportGen Delay Information | ISE Design Suite | Xilinx, Inc. |
| .DLZ | CPT | Pliki z danymi | Crossword Power Tools Crossword Library File | Crossword Power Tools | CPT |
| .DM2 | Interscape | Pliki z danymi | Toad Data Modeler 2 File | Toad Data Modeler | Interscape |
| .DMC | nModal Solutions Inc. | Pliki z danymi | Datamartist Data Canvas File | nModal Solutions Datamartist | nModal Solutions Inc. |
| .DMD | Oracle Corporation | Pliki z danymi | SQL Developer Data Modeler File | SQL Developer Data Model | Oracle Corporation |
| .DME | Interscape | Pliki z danymi | Medical Manager DML System Merged Data | Medical Manager DML System | Emdeon Business Services, LLC |
| .DMG | Apple | Pliki z danymi | Mac OS X Disk Image File | 7-Zip | Igor Pavlov |
| .DMI | BYOND | Pliki z danymi | BYOND Dream Maker Icon File | BYOND | BYOND |
| .DML | Sybase, Inc | Pliki z danymi | DynaScript File | Internet Explorer | Microsoft Corporation |
| .DMM | Seavus | Pliki z danymi | iMindQ Mind Map File | Seavus iMindQ | Seavus |
| .DMO | Wouter van Oortmerssen | Pliki z danymi | Cube 2: Sauerbraten Demo File | Cube 2 Sauerbraten | Open Source |
| .DMP | Microsoft Corporation | Pliki z danymi | Windows Memory Dump File | Microsoft Visual Studio | Microsoft Corporation |
| .DMR | Brain Innovation | Pliki z danymi | BrainVoyager Diffusion Weighted Project File | BrainVoyager QX | Brain Innovation |
| .DMW | ScienceScope | Pliki z danymi | Datamass Ag File | Datamass Ag | ScienceScope |
| .DMY | PhysioNet | Pliki z danymi | SEMIA LTST DB Time Series Data File | SEMIA | PhysioNet |
| .DNA | GSL Biotech LLC | Pliki z danymi | SnapGene DNA File | SnapGene | GSL Biotech LLC |
| .DNC | Microsoft Corporation | Pliki z danymi | Windows Dancer File | Windows Media Center | Microsoft Corporation |
| .DND | European Bioinformatics Institute | Pliki z danymi | ClustalW2 Tree Data | ClustalW2 | European Bioinformatics Institute |
| .DNG | Adobe Systems Incorporated | Pliki z danymi | Digital Negative Image File | MacPhun ColorStrokes | Macphun |
| .DNT | Rockwell Automation Inc. | Pliki z danymi | RSNetWorx Project | RSNetWorx | Rockwell Automation Inc. |
| .DOCKZIP | Stardock Corporation | Pliki z danymi | ObjectDock File | Stardock ObjectDock | Stardock Corporation |
| .DOD | Progress Software Corporation | Pliki z danymi | Progress Artix Data Services Data Model | Progress Artix Data Services | Progress Software Corporation |
| .DOE | Rockwell Automation Inc. | Pliki z danymi | Rockwell Arena Model File | Rockwell Arena Simulation | Rockwell Automation Inc. |
| .DOI | Actuate Corporation | Pliki z danymi | BiRT Data Object Instance File | BIRT | Open Source |
| .DON | Apache Software Foundation | Pliki z danymi | Apache OpenOffice (OpenOffice.org) Log | Apache OpenOffice | Apache Software Foundation |
| .DOP | DxO Labs | Pliki z danymi | DxO Optics Pro Correction Settings File | DxO OpticsPro | DxO Labs |
| .DOT | Microsoft Corporation | Pliki z danymi | Word Document Template | Apache OpenOffice | Apache Software Foundation |
| .DOV | Safer Networking Ltd. | Pliki z danymi | Temporary (Temp) File | FileAlyzer | Safer Networking Ltd. |
| .DOWN | Apple | Pliki z danymi | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .DOX | Microsoft Corporation | Pliki z danymi | Visual Basic Binary UserDocument | Microsoft Visual Studio | Microsoft Corporation |
| .DP | Stefan Hagel | Pliki z danymi | Text Document | Microsoft Notepad | Microsoft Corporation |
| .DP4 | Apian Software | Pliki z danymi | DecisionPad 4 Project | DecisionPad | Apian Software |
| .DPB | Susteen, Inc. | Pliki z danymi | DataPilot Backup File | DataPilot | Susteen, Inc. |
| .DPC | Microsoft Corporation | Pliki z danymi | Microsoft Office Resource File | Microsoft Office | Microsoft Corporation |
| .DPD | David Pilling | Pliki z danymi | Ovation Pro File | Ovation Pro Reader | David Pilling |
| .DPE | Procedimientos-Uno, S.L. | Pliki z danymi | DPwinEHE Project File | DPwinEHE | Interscape |
| .DPF | Open Source | Pliki z danymi | Dargon Package | Dargon | Open Source |
| .DPJ | Delft Spline Systems | Pliki z danymi | DeskProto Project | DeskProto | Delft Spline Systems |
| .DPN | Depiction Inc. | Pliki z danymi | Depiction Data File | Depiction | Depiction Inc. |
| .DPO | DECAdry | Pliki z danymi | DECAdry Express Business Cards Business Card | DECAdry Express Business Cards | DECAdry |
| .DPS | DivX, LLC. | Pliki z danymi | DivX Player 2 Skin File | DivX | DivX, LLC. |
| .DPT | Kingsoft | Pliki z danymi | Kingsoft Presentation Template | Kingsoft Office | Kingsoft |
| .DPX | Kodak | Pliki z danymi | Digital Picture Exchange File | Adobe SpeedGrade | Adobe Systems Incorporated |
| .DQC | Open Source | Pliki z danymi | CP/M Disk Information Data | CP/M | Open Source |
| .DR | Sony Mobile Communications | Pliki z danymi | DRM Rights Object | DRM Packager | Sony Mobile Communications |
| .DRAFT | Apple | Pliki z danymi | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .DRB | Dr. Software | Pliki z danymi | Dr. Beam Pro Data | Dr. Beam Pro | Dr. Software |
| .DRC | Open Source | Pliki z danymi | Open Mobile Alliance DRM Rights Object | Microsoft Notepad | Microsoft Corporation |
| .DRE | DÖRR EDV-Beratung | Pliki z danymi | DReport Exported Report | DReport | DÖRR EDV-Beratung |
| .DRIVE | Apple | Pliki z danymi | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .DRIVERS | Apple | Pliki z danymi | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .DRL | Gerber Technology | Pliki z danymi | Gerber Drill Rack File | Altium Designer | Altium |
| .DRN | Unknown Developer | Pliki z danymi | Darn for DOS Data File | Darn software | Unknown Developer |
| .DRO | Open Source | Pliki z danymi | DOSBox Raw OPL Format | DOSBox | Open Source |
| .DRT | Micrografx | Pliki z danymi | Micrografix Windows Draw Template File | Micrografix Windows Draw | Micrografx |
| .DRX | Adobe Systems Incorporated | Pliki z danymi | Adobe Photoshop Tutorial Data | Adobe Photoshop | Adobe Systems Incorporated |
| .DRY | Unknown Developer | Pliki z danymi | XAIRON Organizer Diary File | XAIRON Organizer | Unknown Developer |
| .DRZ | Unknown Developer | Pliki z danymi | Draz Paint File | XnView MP | XnSoft |
| .DS | DAZ 3D | Pliki z danymi | DAZ Studio 1/2 Script | DAZ Studio | DAZ 3D |
| .DSB | Dell Technologies | Pliki z danymi | Dell DataSafe Backup File | DataSafe Local Backup | Dell Technologies |
| .DSC | Kingsoft | Pliki z danymi | Kingsoft Design Science Equation File | Kingsoft Office | Kingsoft |
| .DSD | Autodesk, Inc. | Pliki z danymi | AutoCAD Drawing Set Description File | Autodesk AutoCAD | Autodesk, Inc. |
| .DSE | DAZ 3D | Pliki z danymi | DAZ Studio Encrypted Script | DAZ Studio | DAZ 3D |
| .DSHADER | Microsoft Corporation | Pliki z danymi | Microsoft Visual Studio Text Data | Microsoft Visual Studio | Microsoft Corporation |
| .DSL | ABBYY | Pliki z danymi | Lingvo Dictionary Data File | ABBYY Lingvo Dictionary | ABBYY |
| .DSR | Activision | Pliki z danymi | Modern Warfare 3 Dedicated Server Recipe File | Call of Duty 4: Modern Warfare | Activision |
| .DSSLIDESHOW | Idea2 s.c. | Pliki z danymi | Desktop Sidebar Slideshow Panel File | Desktop Sidebar | Idea2 s.c. |
| .DSX | DAZ 3D | Pliki z danymi | DAZ Studio XML File | DAZ Studio | DAZ 3D |
| .DSY | Lead System (M) Sdn. Bhd. | Pliki z danymi | Besta Video File | Besta Electronic Dictionaries | Lead System (M) Sdn. Bhd. |
| .DSZ | Orchida Soft | Pliki z danymi | Orchida (OES) Embroidery File | Orchida Embroidery System | Orchida Soft |
| .DT | d-lusion interactive media | Pliki z danymi | Drum Station Machine State File | Drum Station | d-lusion interactive media |
| .DT? | Terry A. Davis | Pliki z danymi | LoseThos Data File | LoseThos | Terry A. Davis |
| .DTA | IWIS | Pliki z danymi | Chain Engineering Database | Chain Engineering | IWIS |
| .DTC | Microsoft Corporation | Pliki z danymi | Windows Application Log File | Microsoft Windows Millenium Edition | Microsoft Corporation |
| .DTD | Syncro Soft | Pliki z danymi | Document Type Definition File | Microsoft Notepad | Microsoft Corporation |
| .DTE | DoroTree Technologies | Pliki z danymi | DoroTree Family Tree Data | DoroTree | DoroTree Technologies |
| .DTERMLICENCE | Decimus Software, Inc. | Pliki z danymi | DTerm Licence File | DTerm | Decimus Software, Inc. |
| .DTH | Microsoft Corporation | Pliki z danymi | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .DTI | Microsoft Corporation | Pliki z danymi | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .DTM | Prodatron | Pliki z danymi | DigiTrakker Audio Module | CocoModX | Open Source |
| .DTR | Swisslog | Pliki z danymi | Swisslog Downtime Analyzer Report | Unknown Software | Unknown Developer |
| .DUMP | Microsoft Corporation | Pliki z danymi | Dump File | macOS | Apple |
| .DUT | Microsoft Corporation | Pliki z danymi | Dutch Localization Language | Microsoft Notepad | Microsoft Corporation |
| .DVC | IBM | Pliki z danymi | Lotus 1-2-3 Data | Lotus 1-2-3 | IBM |
| .DVDFABHDDECRYPTER | Fengtao Software Inc. | Pliki z danymi | DVDFab HD Decrypter File | DVDFab HD Decrypter | Fengtao Software Inc. |
| .DVDFABPLATINUM5 | Fengtao Software Inc. | Pliki z danymi | DVDFab Platinum File | DVDFab | Fengtao Software Inc. |
| .DVDPROJ | Apple | Pliki z danymi | iDVD Project File | Apple iDVD | Apple |
| .DVO | DVO Enterprises | Pliki z danymi | Cook'n Cookbook File | DVO Enterprises Cook'n | DVO Enterprises |
| .DW4 | IBM | Pliki z danymi | Visio/DisplayWrite 4 Text File | DisplayWrite | IBM |
| .DWB | Coryphaeus Software | Pliki z danymi | Designer's Workbench File Format | Designer's Workbench | Coryphaeus Software |
| .DWI | KONAMI | Pliki z danymi | Dance With Intensity Song File | ArrowVortex | Bram van de Wetering |
| .DWM | Open Source | Pliki z danymi | Digital Works Circuit Project | Digital Works | Open Source |
| .DWS | Autodesk, Inc. | Pliki z danymi | AutoCAD Drawing Standards File | Autodesk AutoCAD | Autodesk, Inc. |
| .DWX | Capilano Computing | Pliki z danymi | DesignWorks Viewer Tools Data | DesignWorks | Capilano Computing |
| .DWZ | Corel | Pliki z danymi | DVD MovieFactory Project File | DVD MovieFactory | Corel |
| .DX | Digital Equipment Corporation | Pliki z danymi | DEC WPS Plus File | Microsoft Notepad | Microsoft Corporation |
| .DXL | IBM | Pliki z danymi | Domino XML Language File | Microsoft Notepad | Microsoft Corporation |
| .DXV | Condrey Corporation | Pliki z danymi | DocXchanger Data | DocXchanger | Condrey Corporation |
| .DYNAMO | Apple | Pliki z danymi | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .DZC | Microsoft Corporation | Pliki z danymi | Photosynth Deep Zoom Collection | Microsoft PhotoSynth | Microsoft Corporation |
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