The file extension list you requested is shown on this page. It loads as a table so please give it a moment as some of the lists are quite long. These lists contain basic information: the extension, the name of the program it works with, the specific function of the file, and the company that makes the program. Not all extensions have all of the data. Click on the extension of interest to see the detail page for that extension. Total extensions in this particular list: 332.
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| Extension |
Information |
| U |
Unreal Tournament 2003 System File (Epic Games, Inc.) |
| U |
Subsampled Raw YUV Bitmap |
| U |
Unreal System File |
| U |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| U |
Nitpicker Ipflow File |
| U2 |
Telelogic Tau UML Model |
| U2E |
Unreal Game Translation |
| U2P |
Telelogic Tau UML Program Text File |
| U3D |
Ultimate3D Engine 3D Engine (Ultimate3D) |
| U3D |
Universal 3D File |
| U3I |
Sandisk Launchpad Application Installer file (SanDisk Corporation) |
| U3P |
U3 Platform Install File (U3 LLC.) |
| U4A |
UnInstaller Archive |
| U8 |
Raw Unsigned 8-Bit Audio Data |
| U96 |
EasyZip Temporary File |
| U98 |
Urdu 98 Document |
| UAE |
WinUAE 0.8.22 Game Configuration File |
| UAP |
User Agent Wireless Telephony Profile |
| UAS |
PhotoImpact Backup/Recovery File (Ulead Systems, Inc.) |
| UAX |
Undying |
| UAX |
Unreal / Unreal 2 |
| UAX |
Rune |
| UAX |
Deus Ex |
| UAX |
Harry Potter |
| UAX |
Unified Application eXchange Format (UAX Project) |
| UAX |
Unreal Tournament 2003 Sound (Epic Games, Inc.) |
| UAX |
Unreal Audio File (Epic Games, Inc.) |
| UB |
Audio |
| UB |
Raw Unsigned Byte (8-bit) Data |
| UBB |
BASIC UBAS File |
| UBD |
BASIC UBAS File |
| UBK |
National Construction Estimator 32 User Costbook |
| UBK |
Embiid Reader eBook (Embiid Inc.) |
| UBM |
Iphoto Mtwain Install File |
| UBS |
Tracesrv Bugslayer Utility File |
| UC |
Unreal Tournament Code File (Epic Games, Inc.) |
| UC |
AutoCut Flash Firmware File (Autometrix) |
| UC2 |
UltraCompressor II Compressed Archive (AIPNL) |
| UCC |
National UCC Financing Statement Software Uniform Commercial Code Form (National LawForms, Inc.) |
| UCD |
Prosa/ OM Use Case Diagram |
| UCE |
UniCode Extensions |
| UCF |
Epson Personal Settings Information (Epson Corporation) |
| UCF |
Xilinx Foundation User Constraint File |
| UCG |
ULEAD MediaStudio CG Infinity Graphic (Corel Corporation) |
| UCI |
Samsung YP-P2 Theme |
| UCM |
Urban Chaos Game File |
| UCMN |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UCN |
U-Act Configurator Configuration Storage File (Unisys) |
| UCN |
Compressed Archive |
| UCR |
MicroSim PCBoard Unrouted Nets Report |
| UCS |
Universal Classification Standard Database File |
| UCS |
Homeworld Localized Unicode Strings (Sierra Entertainment, Inc.) |
| UCSETTINGS |
Universal Converter Configuration File (Anthony R. Daly) |
| UCV |
Universal Converter Conversion File (Anthony R. Daly) |
| UCX |
Rational XDE (IBM) |
| UD |
AOL 4.0 (America Online, Inc.) |
| UD |
OmniPage User Dictionary (Nuance Communications, Inc.) |
| UDB |
VBA32 Antivirus Signature File (VirusBlokAda Ltd.) |
| UDB |
Windows2000 Uniqueness Database File (Microsoft Corporation) |
| UDB |
PINO 3-Server File |
| UDB |
Works File (Microsoft Corporation) |
| UDC |
Systems Management Server (SMS) Collection Evaluator Updates Collection (Microsoft Corporation) |
| UDC |
Fh5 US English File |
| UDC |
Acrobat Spelling File (Adobe Systems Incorporated) |
| UDD |
OllyDbg Module Information (Oleh Yuschuk) |
| UDF |
Uyap Dokuman Editoru Document (Türkiye Barolar Birliği) |
| UDF |
Excel User Defined Function (Microsoft Corporation) |
| UDF |
X-ray Diffraction Data File Format |
| UDF |
Windows NT Uniqueness Database File |
| UDF |
Photostyler Image Filter |
| UDI |
Dazzle DVD Complete (Pinnacle Systems, Inc.) |
| UDI |
Corel Graphics Ver 10 Draw Script Textures Bitmap File (Corel) |
| UDL |
Data Link (Microsoft Corporation) |
| UDL |
ADONIS User Export From Database (BOC Group) |
| UDM |
MapView User-Defined Module (MotCreations) |
| UDS |
NHTSA UDS-1992 Crash Test Data |
| UDS |
Sierra Generations Geneology Family File (Sierra Entertainment, Inc.) |
| UDS |
FIMware Database (Uniform Data System for Medical Rehabilitation, a division of UB Foundation Activities, Inc.) |
| UDW |
Raw Unsigned DoubleWord (32-bit) Data |
| UE2 |
Encrypted Archive |
| UEED |
Uconomix Encryption Engine Encrypted Directory (Uconomix Technologies Pvt Ltd) |
| UEEF |
Uconomix Encryption Engine Encrypted File (Uconomix Technologies Pvt Ltd) |
| UEF |
Unified Emulator Format |
| UENC |
UltraEdit Encrypted File (IDM Computer Solutions, Inc.) |
| UEZ |
COOL 3D (Ulead Systems, Inc.) |
| UFA |
GIF Animator Animation Object Information (Ulead) |
| UFA |
UFA Compressed File Archive |
| UFD |
PDP-10 User File Directory |
| UFF |
DataWave Physiological Data File |
| UFI |
UFOCaptureV2 Presets (SonotaCo) |
| UFO |
Total Annihilation Third-party Unit (Cavedog Entertainment) |
| UFO |
PhotoImpact Graphic (Ulead Systems, Inc.) |
| UFO |
Ellisys Visual USB Data (Ellisys) |
| UFSD |
UFS Explorer Professional Recovery RAW Recovery Signatures Database (SysDevSoftware) |
| UG |
Drawing File |
| UGA |
Ulead GIF Animator Project File (Corel Corporation) |
| UH |
Age of Kings (Microsoft Corporation) |
| UHA |
UHARC Compressed Archive |
| UHS |
Universal Hint System File (Universal Hint System) |
| UHTM |
Unreal Tournament File |
| UI |
User Interface |
| UI |
Geoworks UI Compiler Espire Source |
| UI |
Qt User Interface (Qt Software) |
| UID |
IBM Voice Type Users File (IBM) |
| UIF |
WordPerfect Long Prompts (Corel Corporation) |
| UIF |
Magic ISO Universal Image Format File (MagicISO Inc.) |
| UIH |
Geoworks UI Compiler Espire Header |
| UIL |
X-Motif UIL Table |
| UIN |
ICQ 2001+ Saved ICQ Contact Information (ICQ Inc.) |
| uindex |
Newsgroup Index File |
| UIR |
LabWindows User Interface Resource (National Instruments Corporation) |
| UIS |
WindowBlinds Skin |
| UKA |
Fifa World Cup Game Data fe Art Legalscr File |
| UKA |
UKA Data Archive (HRM Systems AG, CH-Winterthur) |
| UKS |
Works File (Microsoft Corporation) |
| UKX |
Unreal Tournament 2003 Animation (Epic Games, Inc.) |
| UK_ |
Mcguiness File |
| UL |
uLAW Audio File |
| ULD |
Procomm Uploaded Files |
| ULF |
Uniware Layout File (Uniware) |
| ULP |
Peugeot Diag 2000 File |
| ULP |
EAGLE Layout Editor Script (CadSoft Computer GmbH) |
| ULS |
Internet Location Service |
| ULT |
UltraTracker Music Module |
| ULW |
ULAW - Sun/NeXT |
| ULX |
CLAN Lexical File (Child Language Data Exchange System) |
| ULX |
Glulx Game |
| ULZ |
USBlyzer (USBlyzer) |
| UM |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UM |
The Land Of UM World File |
| UMB |
MemMaker Backup Archive |
| UMD |
UMD Photobook |
| UMI |
CDDB Database and PC Music Library in PlayCenter |
| UML |
Visual UML Class Diagram & Model (Visual Object Modelers, Inc.) |
| UMOD |
Unreal Self-extracting MOD File (Epic Games) |
| UMOD |
Unreal Tournament (Epic Games, Inc.) |
| UMP |
UModel Project (Altova) |
| UMR |
MyEclipse UML Model Repository (Genuitec, LLC.) |
| UMS |
Rune |
| UMX |
Unreal Tournament 2003 Music (Epic Games, Inc.) |
| UMX |
Unreal/Unreal Tournament Music File (Epic Games, Inc.) |
| UMX |
Deus Ex |
| UMX |
Harry Potter |
| UMX |
U-MYX Player Song Mix Data and Timing Info (U-MYX Ltd.) |
| UNASSIGNED |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNC |
Files and Settings Transfer Wizard Output Folder (Microsoft Corporation) |
| UNCIAL |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UND |
A86 Assembler Undefined Symbols |
| UNF |
Btreive Unformatted File |
| UNI |
MikMod (UniMod) Format |
| UNI |
Forcast Pro Data File |
| UNIKEY |
Unikey Software Protection Solution (SecuTech Solution Inc.) |
| UNION |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNIVERSAL3 |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNIX |
UNIX File |
| UNIX |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNKNOWN |
[None] |
| UNL |
Informix Binary File Created by UNLOAD Command |
| UNLOCK |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNM |
XMap Flight Plan or Flight Plan Statistic File (Delorme) |
| UNPAC |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNPACK |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UNQ |
Fax View File |
| UNQ |
ACT! Saved Unknown Attachment (Best Software CRM Division) |
| UNR |
Unreal Map File |
| UNS |
Visual Navigation Suite Export/Import Settings (Jeppesen Marine, Inc.) |
| UNT |
AutoCAD Unit Definition (Autodesk, Inc.) |
| UNUSED |
Photoline4 Defaults File |
| UNV |
Forecast Pro Univariate Forecast File (Business Forecast Systems, Inc.) |
| UNV |
BusinessObjects/WebIntelligence Universe File |
| UNV |
SDRC I-DEAS File |
| UNX |
Text File |
| UNX |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UN_ |
Ntgraph Setup30 file |
| UOF |
Uniform Office Format |
| UOL |
PhotoImpact Object Library File |
| UP |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UP2 |
Cool3d Plug-ins Board File |
| UPC |
Ultimate Paint (J-T-L Development Inc.) |
| UPCASE |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPD |
dBASE Update File |
| UPD |
VideoStudio Scene Information (Ulead Systems, Inc.) |
| UPD |
Updated Program Data |
| UPD |
Universal Print Driver |
| UPD |
Ulead Private Data (Corel Corporation) |
| UPD |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPD |
ProUpdater Per/Directory Options Setting File |
| UPDATE |
ISAPI Loader New ISAPI Application (EGGcentric) |
| UPDATE |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPDATE |
Program or Data File Update |
| UPDATEALL |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPDATEINFO |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPDATES |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPDF |
UltraPdf Publication (Software995) |
| UPF |
Nokia Phone Digital Photo (Nokia) |
| UPF |
Universal Picture Format Bitmap |
| UPG |
Firmware Upgrade File |
| UPG |
Grafik Anim File |
| UPI |
ULead Photo Impact Program File (Corel Corporation) |
| UPI |
Iphoto4 Programs Plug-in File |
| UPJ |
ULead Project File (Corel Corporation) |
| UPK |
Mass Effect Game File Archive (EA International (Studio and Publishing) Ltd.) |
| UPL |
Starmoney Agent Download File |
| UPL |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UPM |
PenMail Document (UC-Logic Technology Corp.) |
| UPO |
dBASE Compiled Update File |
| UPP |
Uniprint Unified Printer Parameter |
| UPR |
FileMaker User Spelling Dictionary |
| UPS |
Works File (Microsoft Corporation) |
| UPT |
Connectivity Memory Model Update Timing Input File |
| UPX |
ULead Photo Express Saved Image File (Corel Corporation) |
| UPZ |
Starmoney Agent Download File |
| UQM |
The Ur-Quan Masters Archive (The Ur-Quan Masters Team) |
| URBS |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| URD |
Ultra Recall Database (Kinook Software, Inc.) |
| URD-JOURNAL |
Ultra Recall Journal Update File (Kinook Software, Inc.) |
| URF |
Radar ViewPoint Universal Radar Format |
| URF |
ProWORX Nxt User Configurable Register Editor File (Schneider Electric) |
| URF |
AppFace Skin (Matinsoft Inc.) |
| URI |
List of Uniform Resource Identifiers |
| URIS |
List of Uniform Resource Identifiers |
| URL |
Internet Location |
| URLS |
GetRight URL List (Headlight Software, Inc.) |
| URS |
ControlDraw User Requirements Specifier (ControlDraw Ltd.) |
| URT |
Utah Raster Image |
| US |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USA |
Unreal Saved Game File |
| USA |
Office Header File (Microsoft Corporation) |
| USAGE |
Snort File |
| USAGE |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USB |
USB Protocol Analyzer Trace |
| USB |
Syssoft Sandra File |
| USB |
D-Link FM Radio Update |
| USD |
Epson PRINT Image Framer (PIF) Framer File (Seiko Epson Corp.) |
| USE |
MKS Source Integrity File |
| USE |
Log File |
| USE |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USER |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USERPROFILE |
Live Update User Profile (Symantec Corporation) |
| USF |
Core Media Player XML Universal Subtitle Format File (CoreCodec, Inc.) |
| USF |
Nintendo Ultra 64 Sound Format (Nintendo) |
| USI |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USI |
UsiXML UI Description File (Universite Catholique de Louvain-la-Neuve) |
| USK |
Ultraplayer Ultraplayer Playlist File (UltraCo, Inc) |
| USL |
LaserJet Landscape Font |
| USL |
ProWORX Nxt USL Loadables (Schneider Electric) |
| USL |
PC-Bibliothek User Dictionary (Bibliographisches Institut & F.A. Brockhaus AG) |
| USP |
LaserJet Portrait Font |
| USP |
PageMaker Printer Font (Adobe Systems Incorporated) |
| USP |
SIMCA-P/SIMCA-P+ Project (Umetrics AB) |
| USR |
MicroImages User-specific Information (MicroImages, Inc.) |
| USR |
ERGO Receiver Configuration File (Creative Express Corporation) |
| USR |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USR |
Uplink Player Information File (Introversion Software) |
| USR |
Daqarta Extended Audio Data (Interstellar Research) |
| USR |
FileMaker Pro Runtime Engine Database Application (FileMaker, Inc.) |
| USR |
Pegasus Mail User Information (David Harris) |
| USR |
User Database |
| USR |
Photo Paint User Defined Filter (Corel) |
| USS |
WinUAE Saved State |
| USS |
PhotoImpact Exported Slicing Pattern (Ulead Systems, Inc.) |
| UST |
WiFi SiStr Exported User Theme (DNsoft.be) |
| USTAR |
POSIX tar Compressed Archive |
| USX |
Unreal Tournament 2003 Static Mesh (Epic Games, Inc.) |
| USYM |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| USZ |
UsiXML UI Description File (Universite Catholique de Louvain-la-Neuve) |
| UT2 |
Unreal Tournament Map (Epic Games, Inc.) |
| UT2MOD |
Unreal Tournament 2003 Game Modification File (Epic Games) |
| UT3 |
Unreal Tournament 3 Map (Epic Games, Inc.) |
| UT4MOD |
Unreal Tournament 2004 MOD Installation Package (Epic Games) |
| UTC |
BioWare Aurora Engine Creature (BioWare Corp.) |
| UTD |
BioWare Aurora Engine Doors (BioWare Corp.) |
| UTE |
Rukus 110 File |
| UTE |
BioWare Aurora Engine Encounter (BioWare Corp.) |
| UTF |
AOL Updating Files (America Online, Inc.) |
| UTI |
BioWare Aurora Engine Item (BioWare Corp.) |
| UTI |
SafeGuard PrivateCrypto Encrypted Archive (Utimaco Safeware AG) |
| UTI |
Spybot - Search & Destroy Usage Tracking (PepiMK Software) |
| UTIL |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UTIL2 |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UTILITIES |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UTILITY |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UTILS |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UTL |
QuickBooks Data (Intuit Inc.) |
| UTL |
Sound File |
| UTM |
BioWare Aurora Engine Store (BioWare Corp.) |
| UTMP |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UTP |
BioWare Aurora Engine Placeable Object (BioWare Corp.) |
| UTP |
BinPatch Patch Data File |
| UTS |
Spybot - Search & Destroy Include File (PepiMK Software) |
| UTS |
BioWare Aurora Engine Sound (BioWare Corp.) |
| UTT |
BioWare Aurora Engine Trigger (BioWare Corp.) |
| UTW |
BioWare Aurora Engine Waypoint (BioWare Corp.) |
| UTX |
Undying |
| UTX |
Unicode File |
| UTX |
Harry Potter |
| UTX |
Deus Ex |
| UTX |
Unreal Tournament 2003 (or UT 99) Texture (Epic Games, Inc.) |
| UTX |
Rune |
| UTXT |
Various Programs Unicode Text File |
| UU |
Compressed Archive File |
| UUCP |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UUD |
Uudecoded |
| UUE |
Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| UUE |
Uuencoded |
| UUT |
Genesis 2000 (Genesis 2000, Inc.) |
| UV |
EA Games Video File (Electronic Arts, Inc.) |
| UV2 |
Jane's Combat Simulations F-15 |
| UVP |
ULEAD MediaStudio Video Paint Graphic (Corel Corporation) |
| UVR |
Ulead Cool 360 Viewer File (Corel Corporation) |
| UVV |
Listlabl File |
| UVW |
geoManager/geoInterface User View |
| UVX |
Unreal Tournament 2003 Saved Game (Epic Games, Inc.) |
| UW |
Raw Unsigned Word (16-bit) Data |
| UW |
Audio |
| UW |
Unitype GlobalWriter File |
| UWF |
UltraTracker Wave File |
| UWL |
GroupWise User Word List (Novell, Inc.) |
| UWL |
WordPerfect User Word List (Corel Corporation) |
| UWS |
UniTrader 2006 Website Archive (UniTechnology Limited) |
| UWT |
UniTrader Template Archive (UniTechnology Ltd.) |
| UX |
UNIX File |
| UXD |
URLBase URL Database (Terria Development) |
| UXF |
UMLet UML eXchange Format (UMLet Team) |
| UXP |
URLBase URL Database (v. 5.1) (Terria Development) |
| UXX |
Unreal Tournament 2003 Cache (Epic Games, Inc.) |
| UXY |
Orchida Embroidery System (Orchida Soft) |
| UYVY |
Interleaved YUV Raw Image |
| UYVY |
ImageMagick Ver. 5.3.2 Perlmagick File (ImageMagick Studio LLC) |
| UZ |
Unreal Tournament Server File |
| UZE |
Ultimate Zip Compresion Agent |
| UZR |
UZR 3D Streamable 3D File Format |
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