.U | Epic Games | Spilfiler | Unreal Tournament Class Package | Microsoft Windows Media Player | Microsoft Corporation |
.UBS | Microsoft Corporation | Ikke Almindelige Filer | Tracesrv Bugslayer Utility File | Tracesrv Bugslayer Windows Utility Software | Microsoft Corporation |
.UCCAPILOG | Microsoft Corporation | Datafiler | Microsoft UCC API Log File | Microsoft Windows Live Messenger | Microsoft Corporation |
.UCE | Microsoft Corporation | Systemfiler | Windows UCE System File | Microsoft Windows | Microsoft Corporation |
.UDF | Open Source | Disk billedfiler | Universal Disk Format Image File | Microsoft Excel | Microsoft Corporation |
.UG | Autodesk, Inc. | Vektorbilledfiler | Drawing File | ACD Systems Canvas | Microsoft Corporation |
.UGA | Microsoft Corporation | Datafiler | Ulead GIF Animator File | GIF Animator | Microsoft Corporation |
.UH | Ensemble Studios | Spilfiler | Age Of Empires II (The Age Of Kings) File | Age of Empires II | Microsoft Corporation |
.UL | Microsoft Corporation | Indstillingsfiler | Windows Updates Downloader Update List File | Windows Updates Downloader | Microsoft Corporation |
.ULS | Microsoft Corporation | Datafiler | NetMeeting User Location Service File | Microsoft NetMeeting | Microsoft Corporation |
.ULZ | Microsoft Corporation | Indstillingsfiler | Windows Updates Downloader Update List File | Windows Updates Downloader | Microsoft Corporation |
.UMB | Microsoft Corporation | Indstillingsfiler | MemMaker Backup Archive | MS-DOS | Microsoft Corporation |
.UMF | GetMediaHolder.com | Datafiler | MediaHolder Universal Media Format File | Microsoft Notepad | Microsoft Corporation |
.UPD | Various Developers | Tekstfiler | Program Update Information | Microsoft Notepad | Microsoft Corporation |
.UPS | Open Source | Spilfiler | UPS Patch File | Microsoft Works | Microsoft Corporation |
.URI | Microsoft Corporation | Datafiler | List Of Uniform Resource Identifiers | Microsoft Notepad | Microsoft Corporation |
.URL | Microsoft Corporation | Webfiler | Internet Shortcut | Microsoft Notepad | Microsoft Corporation |
.USA | Microsoft Corporation | Datafiler | American English Localization Language File | Microsoft Notepad | Microsoft Corporation |
.USE | Unknown Developer | Tekstfiler | Log File | Microsoft Notepad | Microsoft Corporation |
.USER | Microsoft Corporation | Indstillingsfiler | Visual Studio Project User Options File | Microsoft Notepad | Microsoft Corporation |
.USF | EVGA Corporation | Indstillingsfiler | EVGA Precision X Skin File | Microsoft Notepad | Microsoft Corporation |
.USR | FileMaker Inc. | Databasefiler | FileMaker Pro Database File | Microsoft Notepad | Microsoft Corporation |
.UTB | Unknown Developer | Sikkerhedskopifiler | µTBackup Backup | Microsoft Flight Simulator | Microsoft Corporation |
.UTXT | Open Source | Tekstfiler | Unicode Text File | Microsoft Notepad | Microsoft Corporation |
.UVU | Microsoft Corporation | Datafiler | Movie Maker Video Data | Microsoft Windows Live Movie Maker | Microsoft Corporation |
.UXDC | Microsoft Corporation | Datafiler | Microsoft Excel Data Retrieval Service Connection File | Microsoft Excel | Microsoft Corporation |