| .000 | Microsoft Corporation | System Files | Indexing Service Data File | Microsoft Windows | Microsoft Corporation |
| .120 | bhv | System Files | Winfunktion Mathematik V8.0 Julia Fractal File | WinFunction Mathematics | bhv |
| .170 | Phoenix Technologies | System Files | Award BIOS Upgrade File | Award Software | Phoenix Technologies |
| .190 | bhv | System Files | Winfunktion Mathematik V8.0 Julia Fractal File | WinFunction Mathematics | bhv |
| .1C0 | Phoenix Technologies | System Files | Award BIOS Upgrade File | Award Software | Phoenix Technologies |
| .286 | Microsoft Corporation | System Files | Microsoft Windows Virtual Device Driver | Microsoft Windows 3.x | Microsoft Corporation |
| .2GR | Microsoft Corporation | System Files | Windows VGA Graphic Drivers | Microsoft Windows | Microsoft Corporation |
| .32S | Microsoft Corporation | System Files | Win32s Data | Microsoft Windows 3.x | Microsoft Corporation |
| .386 | Microsoft Corporation | System Files | Windows Virtual Device Driver | Microsoft Windows | Microsoft Corporation |
| .3~6 | Microsoft Corporation | System Files | Windows 3.xx System File | Microsoft Windows | Microsoft Corporation |
| .73U | Texas Instruments, Inc. | System Files | TI-73 Explorer Operating System File | TI Connect | Texas Instruments, Inc. |
| .8XU | Texas Instruments, Inc. | System Files | TI-83 And TI-84 Plus Operating System File | TI Connect | Texas Instruments, Inc. |
| .A83 | Unknown Developer | System Files | EightyOne Sinclair ZX81 ROM File | EightyOne | SourceForge |
| .ACCT | IBM | System Files | IBM AIX System Data | IBM AIX | IBM |
| .ADM | Microsoft Corporation | System Files | Administrative Template File | Microsoft Group Policy Object Editor | Microsoft Corporation |
| .ADML | Microsoft Corporation | System Files | Group Policy Language-Specific Administrative Template | Microsoft Group Policy Object Editor | Microsoft Corporation |
| .ADMX | Microsoft Corporation | System Files | Group Policy Administrative Template File | Microsoft Group Policy Management Console | Microsoft Corporation |
| .ADV | Unknown Developer | System Files | Audio Driver File | Dune | Cryo Interactive Entertainment |
| .AML | Intel Corporation | System Files | ACPI Machine Language File | DSDTSE | otRock |
| .ANI | Microsoft Corporation | System Files | Windows Animated Cursor | ACD Systems ACDSee | ACD Systems |
| .ANN | ABBYY | System Files | Lingvo Dictionary Annotation File | ABBYY Lingvo Dictionary | ABBYY |
| .AQM | Psyberia | System Files | AlpineQuest Map File | Mobile Atlas Creator | Open Source |
| .ASEC | Google | System Files | Android Secure Application File | Google Android SDK | Google |
| .AUG | Red Hat | System Files | Red Hat Linux Shellvars File | Linux | Open Source |
| .AWA | ActiveWord Systems, Inc. | System Files | ActiveWords File | ActiveWords | ActiveWord Systems, Inc. |
| .AWS | Autodesk, Inc. | System Files | AutoCAD Work Space File | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .BCD | Microsoft Corporation | System Files | Windows Boot Configuration Data File | Microsoft Registry Editor | Microsoft Corporation |
| .BCS | The Wavelength | System Files | Batch Compiler Specification File | Batch Compiler | The Wavelength |
| .BEM | Open Source | System Files | Babel Enterprise Module | Babel Enterprise | Open Source |
| .BIO | IBM | System Files | BIOS File | Intel Integrator Toolkit | Intel Corporation |
| .BK1 | Autodesk, Inc. | System Files | Autodesk Backup File | Autodesk AutoCAD Ecscad | Autodesk, Inc. |
| .BK2 | Microsoft Corporation | System Files | Windows Indexing Service File | Microsoft Windows | Microsoft Corporation |
| .BLF | Microsoft Corporation | System Files | CLFS Base Log File | Microsoft Common Log File System (CLFS) | Microsoft Corporation |
| .BMK | return7, LLC | System Files | BillMinder Backup File | return7 BillMinder | return7, LLC |
| .BOM | Apple | System Files | Mac OS X Bill Of Materials File | Echo One File Juicer | Echo One |
| .BPD | Palo Alto Software | System Files | Business Plan Pro File | Business Plan Pro | Palo Alto Software |
| .BSD | IEEE Xplore | System Files | Boundary Scan Description Language Data File | Microsoft Notepad | Microsoft Corporation |
| .BZI | GEEP EDS LLC. | System Files | Darik's Boot And Nuke Kernel Data | Darik's Boot And Nuke | GEEP EDS LLC. |
| .C++ | Bjarne Stroustrup | System Files | C++ Implementation Files | C++ | Bjarne Stroustrup |
| .C2I | Unknown Developer | System Files | Driver File | Unknown Software | Unknown Developer |
| .CAB | Microsoft Corporation | System Files | Windows Cabinet File | 7-Zip | Igor Pavlov |
| .CAP | Microsoft Corporation | System Files | Network Monitor Packet Capture Data File | Microsoft Network Monitor | Microsoft Corporation |
| .CAT | Microsoft Corporation | System Files | Windows Catalog File | Microsoft Windows | Microsoft Corporation |
| .CB | Microsoft Corporation | System Files | Microsoft Clean Boot File | Microsoft Windows | Microsoft Corporation |
| .CDD | CS Odessa | System Files | ConceptDraw PRO Document | ConceptDraw PRO | CS Odessa |
| .CDJ | Padus Software | System Files | Disc Juggler File | DiscJuggler | Padus Software |
| .CDMP | Microsoft Corporation | System Files | WCS Device Model Profile | Microsoft Windows | Microsoft Corporation |
| .CGZ | Wouter van Oortmerssen | System Files | Cube Map File | Cube | Wouter van Oortmerssen |
| .CHG | Quicken | System Files | Quicken Online Data File | Intuit Quicken | Quicken |
| .CHS | Microsoft Corporation | System Files | Windows Chinese Noise-Word List File | Microsoft Windows | Microsoft Corporation |
| .CHT | Nintendo | System Files | SNES Cheat File | ZSNES | Nintendo |
| .CI | Microsoft Corporation | System Files | Windows Content Indexer Catalog File | Microsoft Windows | Microsoft Corporation |
| .CLB | Microsoft Corporation | System Files | COM+ Catalog File | Microsoft COM+ | Microsoft Corporation |
| .CLG | Microsoft Corporation | System Files | Windows Catalog File | Microsoft Windows | Microsoft Corporation |
| .CM0013 | Samsung Electronics | System Files | Samsung Smart TV Index File | Microsoft Word | Microsoft Corporation |
| .CMO | ASUS | System Files | ASUS BIOS File | Microsoft Windows | Microsoft Corporation |
| .CMP | Microsoft Corporation | System Files | Windows Connection Manager Profile | Microsoft Windows Server 2016 | Microsoft Corporation |
| .CNT | Microsoft Corporation | System Files | Help Contents File | Microsoft HTML Help Workshop | Microsoft Corporation |
| .CPI | Sony | System Files | AVCHD Video Clip Information | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .CPL | Microsoft Corporation | System Files | Windows Control Panel Item | Microsoft Windows | Microsoft Corporation |
| .CPQ | Compaq | System Files | Compaq OEM Disc Configuration File | Microsoft Notepad | Microsoft Corporation |
| .CPR | Steinberg | System Files | Cubase Project | Steinberg Cubase | Steinberg |
| .CQ | Open Source | System Files | SYSGEN Replacement Data | CP/M | Open Source |
| .CRASH | Apple | System Files | Mac OS X Crash Log File | Apple TextEdit | Apple |
| .CUR | Unknown Developer | System Files | Windows Cursor File | ACD Systems ACDSee | ACD Systems |
| .DAVMOUNT | Microsoft Corporation | System Files | Windows Based Script Host | Microsoft Windows | Microsoft Corporation |
| .DBL | Microsoft Corporation | System Files | Microsoft Windows XP Product Activation Data | Windows XP | Microsoft Corporation |
| .DDT | Sports Interactive | System Files | Football Manager Keep Player Data File | Football Manager 2016 | Sports Interactive |
| .DDZ | AT&T Labs | System Files | Adaptec SCO Unix Driver Image | Unix | AT&T Labs |
| .DESKLINK | Microsoft Corporation | System Files | Desktop Shortcut | Microsoft Windows | Microsoft Corporation |
| .DESKTHEMEPACK | Microsoft Corporation | System Files | Microsoft Windows Theme Pack | Microsoft Windows 8 | Microsoft Corporation |
| .DEV | Bloodshed Software | System Files | Dev-C++ Project File | Dev-C++ | Bloodshed Software |
| .DEVICEMANIFEST-MS | Microsoft Corporation | System Files | Microsoft Windows Device Metadata | Microsoft Windows | Microsoft Corporation |
| .DEVICEMETADATA-MS | Microsoft Corporation | System Files | Device Metadata Package | Microsoft Windows | Microsoft Corporation |
| .DFU | Apple | System Files | iOS DFU File | Apple iOS | Apple |
| .DIAGCAB | Microsoft Corporation | System Files | Troubleshooting Pack Cabinet File | Microsoft Windows | Microsoft Corporation |
| .DIAGCFG | Microsoft Corporation | System Files | Troubleshooting Pack Configuration File | Microsoft Support Diagnostic Tool | Microsoft Corporation |
| .DIAGPKG | Microsoft Corporation | System Files | Troubleshooting Pack File | Microsoft Support Diagnostic Tool | Microsoft Corporation |
| .DIT | Microsoft Corporation | System Files | Active Directory Information Tree File | Microsoft Active Directory | Microsoft Corporation |
| .DL4 | Lindab | System Files | Lindab Dimsilencer File | DIMsilencer | Lindab |
| .DLL | Microsoft Corporation | System Files | Dynamic Link Library | Microsoft Visual FoxPro | Microsoft Corporation |
| .DLX | DIAL | System Files | DIALux Document | DIAL DIALux | DIAL |
| .DMD | Oracle Corporation | System Files | SQL Developer Data Modeler File | SQL Developer Data Model | Oracle Corporation |
| .DMP | Microsoft Corporation | System Files | Windows Memory Dump File | Microsoft Visual Studio | Microsoft Corporation |
| .DOH | Geoworks Ensemble | System Files | Geoworks Dependency Information File | GEOS (Graphic Environment Operating System) | Geoworks Ensemble |
| .DPB | Susteen, Inc. | System Files | DataPilot Backup File | DataPilot | Susteen, Inc. |
| .DRV | Microsoft Corporation | System Files | Device Driver | Microsoft Windows | Microsoft Corporation |
| .DS | DAZ 3D | System Files | DAZ Studio 1/2 Script | DAZ Studio | DAZ 3D |
| .DSK | Power Software Ltd | System Files | General Disk Image | PowerISO | Power Software Ltd |
| .DSR | Activision | System Files | Modern Warfare 3 Dedicated Server Recipe File | Call of Duty 4: Modern Warfare | Activision |
| .DSS | The International Voice Association (IVA) | System Files | Digital Speech Standard File | DSS Player Lite | Olympus Corporation |
| .DTHUMB | Google | System Files | Android Data Thumbnail | Google Android | Google |
| .DUMP | Microsoft Corporation | System Files | Dump File | macOS | Apple |
| .DVC | IBM | System Files | Lotus 1-2-3 Data | Lotus 1-2-3 | IBM |
| .DVD | Unknown Developer | System Files | DOS Device Driver | MS-DOS | Microsoft Corporation |
| .DYC | Xerox | System Files | Xerox Printer Driver Configuration File | Xerox CentreWare | Xerox |
| .DYL | Psion PLC | System Files | EPOC16:Dynamic Link Library File | EPOC (operating system) | Psion PLC |
| .EBD | Microsoft Corporation | System Files | Windows EBD System File | Microsoft Windows | Microsoft Corporation |
| .ECD | EUROSYSTEMS | System Files | CoCut Plotter Printer Driver | Cocut | EUROSYSTEMS |
| .EFI | Intel Corporation | System Files | Extensible Firmware Interface File | EFI Developer Kit | Slashdot Media |
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