| widget | Yahoo! Widgets Widget |
| wince | Windows CE Executable |
| wll | Microsoft Word Add-In |
| wsc | Windows Script Component File |
| wsf | Windows Script File |
| wsh | Windows Script File |
| wwe | AMP1-16 Update Executable |
| x | Human68k OS Executable |
| x16 | Macromedia Extension Plugin 16 |
| x32 | Macromedia Extension Plugin 32 |
| x86 | Linux X86 Executable File |
| xam | Extensible Application Markup Language |
| xaml | Extensible Application Markup Language |
| xap | Silverlight Application Package |
| xba | OpenOffice.org Basic Module |
| xbap | XAML Browser Application |
| xbe | Xbox Executable File |
| xex | Xbox 360 Executable |
| xnp | XnView AddOn File |
| zcp | Zune HD Application |
| zs | Zephyr Eclipse Server Script |
