| .W | Progress Software Corporation | Harvinaiset Tiedostot | OpenEdge Architect Source Code File | OpenEdge | Progress Software Corporation |
| .W2F | Unknown Developer | Harvinaiset Tiedostot | Unknown File Type | Unknown Software | Unknown Developer |
| .W73 | Unknown Developer | Harvinaiset Tiedostot | Unknown File Type | Unknown Software | Unknown Developer |
| .WAL | Nullsoft | Harvinaiset Tiedostot | Winamp Modern Skin | Nullsoft Winamp | Nullsoft |
| .WBA | Stardock Corporation | Harvinaiset Tiedostot | WindowBlinds Compressed Skin | WindowBlinds | Stardock Corporation |
| .WC4 | Unknown Developer | Harvinaiset Tiedostot | WinCheckIt4 Settings File | Unknown Software | Unknown Developer |
| .WCINV | Microsoft Corporation | Harvinaiset Tiedostot | Windows Meeting Space Invitation File | Windows Meeting Space | Microsoft Corporation |
| .WCM | Corel | Harvinaiset Tiedostot | WordPerfect Macro | Corel WordPerfect X8 | Corel |
| .WCXF | PenPower | Harvinaiset Tiedostot | WorldCard Exchange File | WorldCard Mobile | PenPower |
| .WDSEML | Mozilla | Harvinaiset Tiedostot | Thunderbird Searchable Email File | Mozilla Thunderbird | Mozilla |
| .WEBARCHIV | Unknown Developer | Harvinaiset Tiedostot | Unknown File Type | Unknown Software | Unknown Developer |
| .WEI | Unknown Developer | Harvinaiset Tiedostot | Uncommon File Extension | Unknown Software | Unknown Developer |
| .WER | Microsoft Corporation | Harvinaiset Tiedostot | Windows Error Report File | Microsoft Notepad | Microsoft Corporation |
| .WF2 | Unknown Developer | Harvinaiset Tiedostot | Uncommon File Extension | Unknown Software | Unknown Developer |
| .WGS | ChannelAdvisor | Harvinaiset Tiedostot | Walk-Graph Segment File | RichFX Player | eHelp Corporation |
| .WINDOWSLIV | Unknown Developer | Harvinaiset Tiedostot | Uncommon File Extension | Unknown Software | Unknown Developer |
| .WINDOWSMED | Unknown Developer | Harvinaiset Tiedostot | Unknown File Type | Unknown Software | Unknown Developer |
| .WJE | Mariner Software | Harvinaiset Tiedostot | WinJournal Entry | WinJournal | Mariner Software |
| .WKO | Applied Training Science | Harvinaiset Tiedostot | Workout Template File | RippedPro | Applied Training Science |
| .WKSP | Tethys Solutions | Harvinaiset Tiedostot | Workspace Macro Pro File | Workspace Macro Pro | Tethys Solutions |
| .WM5 | Unknown Developer | Harvinaiset Tiedostot | Dyndlg2 File | Dyndlg2 | Unknown Developer |
| .WMH | Unknown Developer | Harvinaiset Tiedostot | Unknown File Type | Unknown Software | Unknown Developer |
| .WNK | Satish Kumar | Harvinaiset Tiedostot | Wink Presentation | Wink | Satish Kumar |
| .WNS | Broderbund | Harvinaiset Tiedostot | PrintShop Newsletter File | PrintShop | Broderbund |
| .WPJ | Watcom International Corporation | Harvinaiset Tiedostot | Watcom C/C++ Project | Watcom C/C++ | Open Source |
| .WPU | Archaeopteryx Software, Inc. | Harvinaiset Tiedostot | User-specific Project File | Wing IDE | Archaeopteryx Software, Inc. |
| .WRX | Progress Software Corporation | Harvinaiset Tiedostot | Progress File | Progress | Progress Software Corporation |
| .WS1 | Microsoft Corporation | Harvinaiset Tiedostot | WordStar For Windows 1 File | Microsoft Wordstar | Microsoft Corporation |
| .WSQ | UTAU Team | Harvinaiset Tiedostot | UTAU File | UTAU | Vocal Synthesizer |
| .WSZ | Nullsoft | Harvinaiset Tiedostot | Winamp Classic Skin | Nullsoft Winamp | Nullsoft |
| .WT | WildTangent | Harvinaiset Tiedostot | Branded .X 3D Model File | WildTangent FATE | WildTangent |
| .WTC | Logitech | Harvinaiset Tiedostot | Logitech Webcam File | Logitech Webcam Software | Logitech |
| .WTK | Interscape | Harvinaiset Tiedostot | WinTalk URL Address | WinTalk | Interscape |
| .WTP | Satish Kumar | Harvinaiset Tiedostot | Wink Template | Wink | Satish Kumar |
| .WUL | Open Source | Harvinaiset Tiedostot | WinUHA Language File | WinUHA | Open Source |
| .WWD | Microsoft Corporation | Harvinaiset Tiedostot | Works Wizard File | Microsoft Works | Microsoft Corporation |
| .WWK | Corel Corporation | Harvinaiset Tiedostot | Corel WordPerfect Keyboard Layout File | Corel WordPerfect | Corel |
| .WWM | Dalin-Service | Harvinaiset Tiedostot | WeeWheel File | WeeWheel | Dalin-Service |
| .WWZ | Unknown Developer | Harvinaiset Tiedostot | Unknown File Type | Unknown Software | Unknown Developer |
| .WXB | Microsoft Corporation | Harvinaiset Tiedostot | Windows Miscellaneous File | Microsoft Windows | Microsoft Corporation |
| .WXM | Open Source | Harvinaiset Tiedostot | wxMaxima Batch File | wxMaxima | Open Source |
| .WXW | WiNRADiO | Harvinaiset Tiedostot | WiNRADiO Extended Wave File | Unknown Software | Unknown Developer |
| .WYG | CAST Group of Companies Inc. | Harvinaiset Tiedostot | WYSIWYG File | Cast Soft wysiwyg | CAST Software |
| .WYN | Freedom Scientific | Harvinaiset Tiedostot | WYNN Document File | WYNN | Freedom Scientific |
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