| wig | Wiggle Genome Track Data |
| wild | HyperCard WILD Data |
| wimp | Microsoft Windows Icon Palette |
| win | Opera Saved Session |
| win32 | GetDiz Data |
| windowslivecontact | Windows Live Contacts |
| wings | Wings 3D Mesh |
| winmerge | WinMerge Data |
| wir | Mentor Expedition PCB Tool Data |
| wis | InstallShield Help Data |
| witsml | Wellsite Information Transfer Standard Markup Language Data |
| wjf | WinZip Job File |
| wjr | ReGet Junior Data |
| wkd | WiKID Token Data |
| wke | Lotus 1-2-3 Educational Version Worksheet |
| wkg | AutoDesk Softimage Workgroup Data |
| wkl | WaKan Word List Data |
| wko | TrainingPeaks WKO+ Data |
| wko | RippedPro Workout Data |
| wkp | Web CEO Database Backup |
| wksp | Workspace Macro Pro Data |
| wky | WinKeySim MFC Application Data |
| wl | Wanderlust Configuration |
| wl | WISCO Word Power Word List |
| wlb | WinList Bundle File |
| wldprp | SolidWorks Weldment Custom Property Template |
| wlf | Argo WebLoad Upload File |
| wlg | Well Logger v1 Data |
| wlic | WIC SDK License Data |
| wlk | WeatherLink Binary Weather Data |
