| .WPP | Serif | Arquivos de áudio | WebPlus Project File | Serif WebPlus | Serif |
| .WRK | Cakewalk, Inc. | Arquivos de áudio | Cakewalk Music Project | Cakewalk SONAR | Cakewalk, Inc. |
| .WSQ | UTAU Team | Arquivos de áudio | UTAU File | UTAU | Vocal Synthesizer |
| .WUS | WUSSOFT | Arquivos de áudio | WUTG Tagged Audio File | WUSSoft AutoSound | WUSSOFT |
| .WUT | WUSSOFT | Arquivos de áudio | WUTG Tag File | WUTG Editor | WUSSOFT |
| .WV | David Bryant | Arquivos de áudio | WavPack Audio File | Nullsoft Winamp | Nullsoft |
| .WVC | Open Source | Arquivos de áudio | WavPack Correction File | WavPack | Open Source |
| .WVE | Wondershare Software Co., Ltd. | Arquivos de áudio | Wondershare Filmora Project File | Wondershare Filmora | Wondershare Software Co., Ltd. |
| .X3V | Yamaha Corporation | Arquivos de áudio | Yamaha Motif Audio | Translator Professional | Chicken Systems |
| .XA | Electronic Arts | Arquivos de áudio | The Sims Audio File | Electronic Arts SimCity 4 | Electronic Arts |
| .XAD | Riven the Mage | Arquivos de áudio | eXotic ADlib Sound Format File | Unknown Software | Unknown Developer |
| .XFS | Elabtronics Company | Arquivos de áudio | eRacer Sound File | CoreChart | Elabtronics Company |
| .XI | Starbreeze Studios | Arquivos de áudio | Fasttracker 2 Extended Instrument File | Awave Studio | FMJ-Software |
| .XKR | Sing-Magic | Arquivos de áudio | Sing Magic Karaoke Song | Sing-Magic Karaoke | Sing-Magic |
| .XM | Starbreeze Studios | Arquivos de áudio | FastTracker 2 Extended Module | ModPlug Player | Open Source |
| .XMF | Open Source | Arquivos de áudio | Cal3D XML Mesh File | Cal3DViewer | Open Source |
| .XMI | Object Management Group (OMG) | Arquivos de áudio | XML Metadata Interchange File | Eclipse IDE for Java Developers | The Eclipse Foundation |
| .XMS | Alexander Gross | Arquivos de áudio | Music Studio Project | Alexander Gross Music Studio | Alexander Gross |
| .XMZ | Starbreeze Studios | Arquivos de áudio | FastTracker 2 Extended Module | ModPlug Player | Open Source |
| .XP | Starbreeze Studios | Arquivos de áudio | Fastracker 2 Pattern | Fasttracker | Starbreeze Studios |
| .XPA | SoniqCast, LLC | Arquivos de áudio | SoniqSync Extended Playlist | SoniqSync | SoniqCast, LLC |
| .XPF | Open Source | Arquivos de áudio | Linux MultiMedia Studio Preset File | LMMS | Open Source |
| .XPL | Interscape | Arquivos de áudio | LcdStudio Playlist File | LCDStudio | Interscape |
| .XRNS | Renoise.com | Arquivos de áudio | Renoise Song File | Renoise | Renoise.com |
| .XSB | Microsoft Corporation | Arquivos de áudio | XACT Sound Bank | Microsoft XACT | Microsoft Corporation |
| .XSP | Open Source | Arquivos de áudio | Kodi Smart Playlist File | Kodi | Open Source |
| .XSPF | VideoLAN | Arquivos de áudio | XSPF Playlist File | VLC Media Player | VideoLAN |
| .XT | Derick Rethans | Arquivos de áudio | Xdebug Trace File | Xdebug | Derick Rethans |
| .XWB | Microsoft Corporation | Arquivos de áudio | XACT Wave Bank | Microsoft XACT | Microsoft Corporation |
| .XWC | Starbreeze Studios | Arquivos de áudio | Starbreeze Sound Data | Knights of the Temple | Starbreeze Studios |
| .XWV | Valve | Arquivos de áudio | Valve Xbox360 Audio Data | Valve Source SDK | Valve |
| .YGD | Open Source | Arquivos de áudio | YouGooDai Playlist File | YouGooDai | Open Source |
| .YM | Atari Corporation | Arquivos de áudio | Atari ST Audio File | Nullsoft Winamp | Nullsoft |
| .YNX | Unknown Developer | Arquivos de áudio | Segmax Seqprest Compressed File | Unknown Software | Unknown Developer |
| .Z00 | Casio Computer Co., Ltd. | Arquivos de áudio | Casio WK-3000 Rythm Data | Casio Data Manager | Casio Computer Co., Ltd. |
| .ZAB | VideoLAN | Arquivos de áudio | Zipped Audio Book | VLC Media Player | VideoLAN |
| .ZAF | Zoom Corporation | Arquivos de áudio | Zoom Audio Data | Zoom Player | Inmatrix Media Solutions |
| .ZAX | Zaxcom | Arquivos de áudio | Zaxcom Audio Data | Unknown Software | Unknown Developer |
| .ZEL | Andrew Maclean | Arquivos de áudio | Zel MIDI Source File | Zel | Andrew Maclean |
| .ZPA | zplane.development GmbH & Co. KG | Arquivos de áudio | Vielklang Audio Metadata File | Steinberg Cubase | Steinberg |
| .ZPL | Inmatrix Media Solutions | Arquivos de áudio | Zoom Player Play List | Zoom Player | Inmatrix Media Solutions |
| .ZVD | Zyxel Communications | Arquivos de áudio | ZyXEL Voice File | Zyxel Z-Fax modem Software | Zyxel Communications |
| .ZVR | SAFA Inc. | Arquivos de áudio | SAFA Media Audio File | Microsoft Windows Media Player | Microsoft Corporation |
| .ZYX | Zyxel Communications | Arquivos de áudio | ZyXEL Voice File | Zyxel Z-Fax modem Software | Zyxel Communications |
| ._1 | Interscape | Arquivos de áudio | Tuningwrench Audio Utility Compressed Audio | Tuningwrench | Interscape |
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