| wcd | Microsoft Works Calendar |
| wcf | FRAMES Water Concentration File |
| wcinv | Windows Meeting Space Data |
| wck | WaterCAD Data |
| wcl | WinCatalog Light Database |
| wcmm | Bamboo Dock Application Data |
| wcrypt | Webcrypto-crypt Encrypted Data |
| wcs | WhopSee Compressed Skin |
| wct | WCT Reader Index File |
| wcu | CueCard Saved Flashcards Data |
| wcxf | WorldCard Mobile Exchange Data |
| wcz | Chameleon Clock Wallpaper |
| wd3 | Offline Explorer Data |
| wda | AutoCAD Electrical Project User Attributes Data |
| wdc | SOBEK Wind Data |
| wdc | WinDaq Waveform Browser Data |
| wdh | WinDaq High Resolution Data |
| wdl | AutoCAD Electrical Project Labels Data |
| wdn | AutoCAD Electrical Project Terminal Numbering Data |
| wdq | Offline Explorer Queue |
| wdq | WinDaq Acquired Data |
| wdr | AutoCAD Electrical Project Ratings Data |
| wdseml | Thunderbird Searchable Email File |
| wdsp | WebDrive Data |
| wdt | AutoCAD Electrical Project Titles Data |
| wdv | TracePlus Web Detective Data |
| wdw | AutoCAD Electrical Project Wires Data |
| wea | Autodesk Ecotect Analysis Weather Data |
| webarchive | Safari Web Archive |
| webbookmark | Safari Web Bookmark Data |
| webhistory | Safari Web History Data |
| webinar | GoToWebinar Session Data |
| weboogl | WebOOGL Data |
| webpart | Microsoft Sharepoint Web Part |
| webtest | Fiddler Saved WebTest Data |