| .NLS | Uri Wilensky | Systemdateien | NetLogo Source Code File | MacroMates TextMate | MacroMates |
| .NT | Microsoft Corporation | Systemdateien | Windows NT Startup File | Microsoft Windows | Microsoft Corporation |
| .NU6 | Symantec Corporation | Systemdateien | Norton Utilities System DLL File | Norton Utilities | Symantec Corporation |
| .NXS | Unknown Developer | Systemdateien | AdaOS Support Module | Unknown Software | Unknown Developer |
| .ODR | Open Source | Systemdateien | OpenIV Model Data | OpenIV | Open Source |
| .OSC | OpenStreetMap | Systemdateien | OpenStreetMap Change File | Merkaartor | Bart Vanhauwaert, Chris Browet, Ladislav Láska, and others |
| .OTE | FTP Software | Systemdateien | TNVTPlus Teach Mode Script File | TNVTPlus | FTP Software |
| .OV3 | Microsoft Corporation | Systemdateien | DOS Overlay File | MS-DOS | Microsoft Corporation |
| .P5X | Microsoft Corporation | Systemdateien | Microsoft Windows System Data | Microsoft Windows | Microsoft Corporation |
| .PANIC | Open Source | Systemdateien | Kernel Panic File | Notepad++ | Don Ho |
| .PAT | Autodesk, Inc. | Systemdateien | AutoCAD Hatch Pattern File | Autodesk AutoCAD | Autodesk, Inc. |
| .PBD | EaseUS | Systemdateien | EaseUS Todo Backup Backup File | EaseUS Todo Backup | EaseUS |
| .PCF | Blackstrip Studios | Systemdateien | PaintCAD Font | PaintCAD | Blackstrip Studios |
| .PCI | Microsoft Corporation | Systemdateien | PCI Miniport Data | Microsoft Windows | Microsoft Corporation |
| .PCK | Microsoft Corporation | Systemdateien | System Center Configuration Manager Package File | Microsoft system center configuration manager | Microsoft Corporation |
| .PD0 | SonTek | Systemdateien | SonTek Firmware File | Unknown Software | Unknown Developer |
| .PDL | PDL Developerment Team | Systemdateien | Perl Data Language File | perldl | Open Source |
| .PDR | Microsoft Corporation | Systemdateien | Windows Port Driver | Windows Control Panel | Microsoft Corporation |
| .PFX | Various Developers | Systemdateien | PKCS #12 Certificate File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .PIT | Samsung Electronics | Systemdateien | Samsung Phone Firmware File | Google Android | Google |
| .PLK | Advanced Micro Devices, Inc. | Systemdateien | AMD ATI Radeon Video Driver | ATI Multimedia Center | Advanced Micro Devices, Inc. |
| .PNF | Microsoft Corporation | Systemdateien | Precompiled INF File | Microsoft Windows | Microsoft Corporation |
| .POL | Microsoft Corporation | Systemdateien | Windows Policy File | Registry.Pol Viewer Utility | SDM Software |
| .PPD | Adobe Systems Incorporated | Systemdateien | PostScript Printer Description File | Adobe PageMaker | Adobe Systems Incorporated |
| .PPM | The GIMP Development Team | Systemdateien | Portable Pixmap Image File | Adobe Photoshop | Adobe Systems Incorporated |
| .PRD | SoftMaker Software | Systemdateien | SoftMaker Presentations Document | Softmaker Office | SoftMaker Software |
| .PREFPANE | Apple | Systemdateien | Mac OS X System Preference Pane | Apple OS X | Apple |
| .PRF | Microsoft Corporation | Systemdateien | Outlook Profile File | Microsoft Outlook 2016 | Microsoft Corporation |
| .PRINTEREXPORT | Microsoft Corporation | Systemdateien | Windows Printer Migration File | Microsoft Windows 7 | Microsoft Corporation |
| .PROFILE | GNU Operating System | Systemdateien | Bash Shell Profile | MacroMates TextMate | MacroMates |
| .PROP | Google | Systemdateien | Android Build Properties File | Google Android | Google |
| .PRS | Software Publishing Corporation (SPC) | Systemdateien | Harvard Graphics Presentation | Corel Presentations X8 | Corel |
| .PRT | PTC | Systemdateien | Pro/ENGINEER Part File | Autodesk Fusion 360 | Autodesk, Inc. |
| .PS2 | Datel | Systemdateien | Sharkport Saved Game File | PS2 Save Builder | Interscape |
| .PSSC | Microsoft Corporation | Systemdateien | Windows PowerShell Session Configuration File | Microsoft Windows | Microsoft Corporation |
| .PWL | Microsoft Corporation | Systemdateien | Windows Password List | Proactive System Password Recovery | ElcomSoft |
| .PXE | Open Source | Systemdateien | Linux, Unix Network Bootable Image | Linux | Open Source |
| .QCC | Niobrara R&D Corporation | Systemdateien | NIOBRARA QUCM Firmware File | Unknown Software | Unknown Developer |
| .QPR | Microsoft Corporation | Systemdateien | FoxPro Generated Query Program | Microsoft Visual FoxPro | Microsoft Corporation |
| .QTS | Apple | Systemdateien | QuickTime System File | Apple QuickTime Player | Apple |
| .QVM | Open Source | Systemdateien | Q Virtual Machine | Q (emulator) | Open Source |
| .RAT | World Wide Web Consortium (W3C) | Systemdateien | PICS Rating File | Microsoft Notepad | Microsoft Corporation |
| .RBH | RBH Access | Systemdateien | RBH Access Technologies Firmware | Unknown Software | Unknown Developer |
| .RC2 | Microsoft Corporation | Systemdateien | Visual Studio Resources File | Microsoft Visual Studio | Microsoft Corporation |
| .RCO | Sony | Systemdateien | PlayStation Portable File | RCO Editor | Open Source |
| .RDZ | Mandriva S.A. | Systemdateien | Mandrake Linux Install File | Mandriva Linux One | Mandriva S.A. |
| .REG | Microsoft Corporation | Systemdateien | Registry File | Windows Registry Editor | Microsoft Corporation |
| .RESTORELIST | Microsoft Corporation | Systemdateien | Microsoft Windows File System Permission | Microsoft Windows | Microsoft Corporation |
| .RIO | IBM | Systemdateien | IBM AIX System Data | IBM AIX | IBM |
| .RMT | The Catalina Group | Systemdateien | Router Firmware File | Internet Explorer | Microsoft Corporation |
| .RPP | Cockos Incorporated | Systemdateien | REAPER Project | REAPER | Cockos Incorporated |
| .RQF | R-Quest Technologies | Systemdateien | R-Quest Duplication Systems Firmware Update File | TrueNet | R-Quest Technologies |
| .RUF | Samsung Electronics | Systemdateien | Samsung DVD And Blu-ray Player Firmware File | Windows Built-in USB Drive Software | Microsoft Corporation |
| .RVP | Sharp Electronics | Systemdateien | Sharp Blu-ray Player Firmware File | Unknown Software | Unknown Developer |
| .RX | Microsoft Corporation | Systemdateien | MS-DOS 7 Data | Microsoft Windows | Microsoft Corporation |
| .SAVER | Apple | Systemdateien | Mac OS X Screen Saver | Apple OS X | Apple |
| .SB | MIT Media Lab | Systemdateien | Scratch Project File | MIT Scratch | MIT Media Lab |
| .SBF | Google | Systemdateien | Android System File | Google Android | Google |
| .SBN | ESRI | Systemdateien | ESRI Spatial Binary File | ESRI ArcGIS for Desktop | ESRI (Environmental Systems Research Institute) |
| .SCF | Microsoft Corporation | Systemdateien | Windows Explorer Command | Microsoft Windows | Microsoft Corporation |
| .SCHEMAS | Open Source | Systemdateien | GConf Schema Definition File | GNU Emacs | GNU Project |
| .SCR | Microsoft Corporation | Systemdateien | Windows Screensaver File | Microsoft Windows | Microsoft Corporation |
| .SCRIPT | Unknown Developer | Systemdateien | Generic Script File | LibreOffice | The Document Foundation |
| .SDG | Golden Software LLC | Systemdateien | Strater Project File | Strater | Golden Software LLC |
| .SDT | Intuit, Inc. | Systemdateien | QuickBooks Data File | Intuit QuickBooks Pro | Intuit, Inc. |
| .SERVICE | Lennart Poettering and Kay Sievers | Systemdateien | Systemd Service File | Linux | Open Source |
| .SF | Institut de Recherche et de Coordination Acoustique/Musique (IRCAM) | Systemdateien | IRCAM Sound File | Awave Studio | FMJ-Software |
| .SF0 | Microsoft Corporation | Systemdateien | Windows Sytem File Check File | Microsoft Windows | Microsoft Corporation |
| .SFCACHE | Microsoft Corporation | Systemdateien | ReadyBoost Cache File | Microsoft Windows | Microsoft Corporation |
| .SFE | Unknown Developer | Systemdateien | Logomatic V2 Firmware | Unknown Software | Unknown Developer |
| .SHA | Corel | Systemdateien | CorelDraw Shader File | CorelDRAW Graphics Suite | Corel |
| .SHD | Microsoft Corporation | Systemdateien | Windows Print Job Shadow File | Microsoft Windows | Microsoft Corporation |
| .SHS | Microsoft Corporation | Systemdateien | Microsoft Scrap File | Microsoft Excel | Microsoft Corporation |
| .SID | Valve | Systemdateien | Steam Game Data Backup File | Steam | Valve |
| .SIN | Big Huge Games | Systemdateien | Rise Of Nations Campaign Media File | Rise Of Nations | Big Huge Games |
| .SL | SourceForge | Systemdateien | Unix Software License File | Vi | SourceForge |
| .SPARC | Skype Technologies | Systemdateien | Skype Plugin Archive | Skype | Skype Technologies |
| .SPL | Microsoft Corporation | Systemdateien | Windows Print Spool File | Microsoft Windows | Microsoft Corporation |
| .SQM | Microsoft Corporation | Systemdateien | Service Quality Monitoring File | Microsoft Windows | Microsoft Corporation |
| .SREC | Motorola | Systemdateien | Motorola S-record Data | SRecord | Open Source |
| .STR | dBase, LLC | Systemdateien | dBASE Structure List Object File | dBase | dBase, LLC |
| .STY | Jørgen Sørensen / Jososoft | Systemdateien | Yamaha/Korg Keyboard Style | Style Fixer | Jørgen Sørensen / Jososoft |
| .SWAP | Microsoft Corporation | Systemdateien | Swap File | Microsoft Windows | Microsoft Corporation |
| .SWP | Microsoft Corporation | Systemdateien | Swap File | Microsoft Windows | Microsoft Corporation |
| .SYS | Microsoft Corporation | Systemdateien | Windows System File | Microsoft Windows | Microsoft Corporation |
| .TBR | Adobe Systems Incorporated | Systemdateien | Adobe Photoshop Custom Toolbar Preset | Adobe Photoshop | Adobe Systems Incorporated |
| .THEME | Microsoft Corporation | Systemdateien | Microsoft Plus! Desktop Theme | Microsoft Windows | Microsoft Corporation |
| .TNC | Texas Instruments, Inc. | Systemdateien | Texas Instruments TI-Nspire CAS OS Image | TI-Nspire Student Software | Texas Instruments, Inc. |
| .TOS | Atari Corporation | Systemdateien | Atari ST TOS Archive File | The Operating System (TOS) | Atari Corporation |
| .UBL | Texas Instruments, Inc. | Systemdateien | DM35x User Boot Loader Data | DM35x, | Texas Instruments, Inc. |
| .UCE | Microsoft Corporation | Systemdateien | Windows UCE System File | Microsoft Windows | Microsoft Corporation |
| .UPD | Various Developers | Systemdateien | Program Update Information | Microsoft Notepad | Microsoft Corporation |
| .UX | AT&T Labs | Systemdateien | Unix File | Unix | AT&T Labs |
| .UXZ | IBM | Systemdateien | IBM Flex CMM Update Data | CMM Firmware | IBM |
| .VAP | Dialogic | Systemdateien | Dialogic Indexed Voice Audio File | Syntellect VoiceXML Studio | Syntellect |
| .VCE | Avanset | Systemdateien | Visual CertExam Suite Exam File | Visual CertExam Suite | Avanset |
| .VDX | Microsoft Corporation | Systemdateien | Visio Drawing XML File | OmniGraffle | The Omni Group |
| .VET | Lectra | Systemdateien | Lectra Cutter's Must File | Modaris | Lectra |
| .VFS | Unknown Developer | Systemdateien | Virtual File System Index | GnomeVFS | GNOME |
| .VGA | Microsoft Corporation | Systemdateien | VGA Display Driver | Microsoft Windows | Microsoft Corporation |
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