| File extension |
File description |
Developer/Producer |
| .u |
Unreal Tournament Class Package |
Epic Games |
| .u10 |
UFile 2010 Tax Return |
Dr Tax Software |
| .u11 |
UFile 2011 Tax Return |
Dr Tax Software |
| .u12 |
UFile 2012 Tax Return |
Dr Tax Software |
| .u3d |
Universal 3D File |
3D Industry Forum |
| .u3i |
U3 Application Information File |
N/A |
| .u3p |
U3 Smart Application |
SanDisk |
| .u8 |
3D Lemmings Audio File |
Clockwork Games |
| .uax |
Unreal Audio Package |
Epic Games |
| .ub |
Unsigned Byte Audio File |
N/A |
| .ubj |
Universal Binary JSON File |
The Buzz Media |
| .ubox |
Universe Sandbox Data File |
Universe Sandbox |
| .uc |
UnrealScript Class |
N/A |
| .uc2 |
UltraCompressor 2 Archive |
N/A |
| .uccapilog |
Microsoft UCC API Log File |
Microsoft |
| .uce |
Windows UCE System File |
Microsoft |
| .ucf |
WebEx Media File |
Cisco Systems |
| .uci |
UFS Explorer Backup File |
SysDevSoftware |
| .ucl |
Killing Floor System File |
Tripwire Interactive |
| .ucm |
Crazy Machines Model File |
Viva Media |
| .uct |
UC Browser Theme File |
UC Mobile |
| .ud |
OmniPage User Dictionary |
Nuance Communications |
| .udb |
Dynamics AX User Database File |
Microsoft |
| .udc |
Adobe InDesign User Dictionary |
Adobe Systems |
| .udcx |
Universal Data Connection File |
Microsoft |
| .udeb |
Debian Package File |
The Debian Project |
| .udf |
Universal Disk Format File |
Optical Storage Technology Association |
| .udk |
Unreal Engine Map File |
Epic Games |
| .udl |
Microsoft Universal Data Link File |
Microsoft |
| .uds |
Sierra Generations File |
Sierra |
| .uea |
Protector Suite QL Encrypted Archive |
AuthenTec |
| .ufo |
Ulead File Object |
Ulead |
| .ufr |
Ultra Fractal File |
Frederik Slijkerman |
| .ufs |
FreeBSD Unix File System File |
The FreeBSD Project |
| .ufs.uzip |
Compressed Unix File System File |
The FreeBSD Project |
| .uha |
UHarc Compressed Archive |
UHarc |
| .uhtml |
UC Browser Saved Webpage |
UC Mobile |
| .ui |
User Interface File |
Nokia |
| .uibak |
UltraISO Backup Disk Image |
EZB Systems |
| .uif |
Universal Image Format Disc Image |
MagicISO |
| .uis |
WindowBlinds User Interface Specification |
Stardock |
| .ukx |
Unreal Animation Package |
Epic Games |
| .ulaw |
Raw u-Law Audio File |
N/A |
| .ulf |
Universal List File |
N/A |
| .uls |
NetMeeting User Location Service File |
Microsoft |
| .ult |
UltraTracker Module |
N/A |
| .ulw |
u-Law Audio File |
N/A |
| .ulz |
USBlyzer Data Capture File |
USBlyzer |
| .umf |
MediaHolder Universal Media Format File |
GetMediaHolder.com |
| .uml |
UML Data Object Model |
N/A |
| .umlclass |
UML Class Model |
N/A |
| .umod |
Unreal Tournament Module File |
Epic Games |
| .ums |
Rune 3D Mesh File |
Human Head Studios |
| .umx |
Unreal Music Package |
Epic Games |
| .unauth |
SiteMinder Unauthorized Message File |
Netegrity |
| .uni |
MikMod UniMOD Module |
N/A |
| .unity |
Unity Scene File |
Unity Technologies |
| .unity3d |
Unity Web Player File |
Unity Technologies |
| .unitypackage |
Unity Package File |
Unity Technologies |
| .unk |
Unknown File |
N/A |
| .unknown |
Unknown File Type |
N/A |
| .unl |
Garmin Unlock File |
Garmin |
| .unr |
Unreal Level Map |
N/A |
| .unt |
AutoCAD Unit Definition File |
Autodesk |
| .unx |
Unix Text File |
N/A |
| .uof |
Uniform Office Document |
N/A |
| .uop |
Uniform Office Presentation |
N/A |
| .uos |
Uniform Office Spreadsheet |
N/A |
| .uot |
Uniform Office Document |
N/A |
| .upd |
Program Update Information |
N/A |
| .update |
ISAPI Update File |
EggCentric |
| .updatr |
iConomy Update File |
Nijikokun |
| .upf |
MicroStation User Preferences File |
Bentley Systems |
| .upg |
Upgrade File |
N/A |
| .upk |
Unreal Engine 3 Package |
Epic Games |
| .upoi |
iGO Points of Interest File |
Nav N Go |
| .upr |
Fractal Parameters File |
N/A |
| .upx |
Ultimate Packer for eXecutables File |
Markus Oberhumer |
| .uqm |
The Ur-Quan Masters Game Data File |
The Ur-Quan Masters |
| .url |
Internet Shortcut |
N/A |
| .urr |
Uniface Signatures File |
Compuware |
| .urt |
Utah Raster Toolkit File |
N/A |
| .usa |
Unreal Saved Game File |
Epic Games |
| .useq |
USeq Genome Data File |
Huntsman Cancer Institute |
| .user |
Visual Studio Project User Options File |
Microsoft |
| .userprofile |
Norton Antivirus User Profile File |
Symantec |
| .usertile-ms |
Windows 8 User Tile File |
Microsoft |
| .usf |
Nintendo 64 Music File |
N/A |
| .usflib |
Nintendo 64 Song Library |
N/A |
| .usm |
USM Game Video File |
N/A |
| .usr |
FileMaker Pro Database File |
FileMaker |
| .ust |
UTAU Sequence Text File |
UTAU |
| .ustar |
Uniform Standard Tape Archive Format File |
N/A |
| .usx |
Unreal Static Meshes |
Epic Games |
| .ut2 |
Unreal Tournament Map |
Epic Games |
| .ut2mod |
Unreal Tournament 2003/2004 Module File |
Epic Games |
| .ut3 |
Unreal Tournament 3 Map File |
Epic Games |
| .ut4mod |
Unreal Tournament 2004 Module |
Epic Games |
| .ut8 |
Ghost Master Language File |
Sick Puppies |
| .utc |
Bioware Creature File |
BioWare |
| .utf8 |
Unicode UTF8-Encoded Text Document |
N/A |
| .utw |
Unity Whirld File |
Aubrey Falconer |
| .utx |
Unreal Texture Package |
Epic Games |
| .utxt |
Unicode Text File |
N/A |
| .utz |
UIQ Theme Package |
UIQ Technology |
| .uu |
Uuencoded File |
N/A |
| .uud |
UUDecoded File |
N/A |
| .uue |
Uuencoded File |
N/A |
| .uvf |
Uncertain Value Format |
N/A |
| .uvx |
Unreal Tournament 2003 Saved Game |
Epic Games |
| .uw |
Unsigned Word Audio File |
N/A |
| .uwf |
UltraTracker Wave File |
N/A |
| .uwl |
User Word List File |
Corel |
| .uxx |
Unreal Tournament Cache |
N/A |
| .uzip |
FreeBSD Compressed Disk Image |
Maxim Sobolev |
