| .DAT | Data |
| .DB | Table - Paradox |
| .DBC | Visual FoxPro database (filename extension). |
| .DBF | Database File - dBASE |
| .DBT | Database text - dBASE |
| .DBX | DATABEAM graphics |
| .DCA | IBM text |
| .DCS | Color Separation - EPS |
| .DCT | Dictionary |
| .DD | Disk Doubler |
| .DDI | Disk Doubler Image (filename extension). |
| .DEF | Definition - C++ (filename extension). |
| .DER | Certificate (filename extension). |
| .DEV | Device driver file (filename extension). |
| .DG | Autotrol graphics |
| .DGN | Intergraph graphics |
| .DIB | DIB graphics - Windows |
| .DIC | Dictionary |
| .DIF | Data Interchange Format spreadsheet |
| .DLL | Dynamic link library |
| .DOC | Document file |
| .DOT | Document Template - Microsoft Word (filename extension). |
| .DOX | MultiMate document |
| .DPI | Dots Per Inch - graphics |
| .DPR | Delphi project file (filename extension). |
| .DRV | Driver |
| .DRW | Designer graphics |
| .DS4 | Designer graphics, version 4 |
| .DSF | Designer graphics, version 6 |
| .DWG | AutoCAD vector format |
| .DWG | Drawing - AutoCAD (filename extension). |
| .DX | Document Imaging |
| .DXF | AutoCAD vector format |
| .ED5 | EDMICS graphics |
| .EMF | Enhanced Windows Metafile (filename extension). |
| .eml | electronic mail |
| .enc | encoded |
| .EPS | Encapsulated PostScript format |
| .ESI | Esri plot file |
| .EXE | Executable file -- machine code |
| .FAX | Fax |
| .FDX | Force Index |
| .FH3 | Aldus Freehand 3 (filename extension). |
| .FLC | AutoDesk animation |
| .FLD | Thumbnail folder - Hijaak |
| .FLI | AutoDesk animation |
| .FLR | Live3D (filename extension). |
| .FLT | Filter - graphics conversion |
| .FM | Framemaker (filename extension). |
| .FM3 | Format for 1-2-3 Version 3 |
| .FMT | Format - dBASE |
| .FNT | Font |
| .FOG | Fontographer font (filename extension). |
| .FON | 1. Bitmapped Font - Windows 2. Phone |
| .FOR | FORTRAN |
| .FOT | Windows TrueType font |
| .FOX | FoxBase |
| .FP | Claris FileMaker Pro (filename extension). |
| .FP1 | Flying Pigs (filename extension). |
| .FP3 | Filemaker Pro 3 |
| .FPX | FlashPix bitmap (filename extension). |
| .FRM | Form design -- Visual Basic |
| .FRS | WordPerfect Graphics Driver |