: U

.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