List of All the File Extensions Formats and Types Starting With the Letter X
| File Extension | Description |
| .XA0 | Xtree Gold Dos help |
| .XAB | Microsoft Outlook Express address book |
| .XAC | SimCity Societies game |
| .XAM | Version 2 Examiner Corporation assessment item bank |
| .XAPPL | Virtual Application Studio XML application configuration |
| .XAV | Final Draft AV document |
| .XDF | Extended disk format image Externally Defined Function Milnta APL transfer function ProWORX Nxt extended memory data Workshare synergy X68000 image |
| .XE0 | XtreeGold Dos help |
| .XEJ | Microsoft Expression Encoder job |
| .XEL | Microsoft Expression Encoder 3.0 live jobs |
| .XEQ | Sage MAS 90 data |
| .XER | Primavera Project Management Propriety Exchange Format |
| .XESC | Microsoft Expression Encoder screen capture |
| .XET | X-Genics eManager process definition |
| .XEV | X-Genics eManager auto-update |
| .XEZ | X-Genics eManager template package |
| .XI | Fastracker 2.0 instrument |
| .XIB | Apple Interface Builder |
| .XIM | X11 Xim Toolkit bitmap |
| .XIX | IIS NNTP subject lists |
| .XLS | Microsoft Excel 97 to 2003 workbook Microsoft Works spreadsheet SolidWorks Excel based BOM template |
| .XPI | Firefox browser extension |