| grph | GRPH Data File |
| grr | Gradekeeper Class Roster |
| grs | Getright Skin |
| grt | Grapher Template |
| gru | FXpansion GURU Preset |
| grv | CART Grove Data |
| grv | Microsoft Office Groove File |
| grx | Getright Exported List |
| grxml | XML Grammar File |
| gs | GemStone Document |
| gs1 | Genecyst Emulator Saved State |
| gs3 | GameStarter File |
| gse | GeneSys 3 Export File |
| gsf | GameExchange2 Skeleton Data |
| gsf | GEMPAK Map File |
| gsf | z-Tree GameSafe Data |
| gsf | Gwyddion Simple Field File |
| gsk | GSAK Macro File |
| gsr2 | Golden Software Reference |
| gss | Geometer Sketchpad Script |
| gsv | Gameshark SP Save File |
| gsx | Genecyst Emulator Saved State |
| gt6 | Topcon Link GTS-6 Raw Data |
| gt7 | Topcon Link GTS-7 Raw Data |
| gtable | Google Drive Fusion Table |
| gtar | GNU Tar Archive |
| gtb | Midas GTS Data File |
| gtd | GT Designer 2 Data |
| gte | GigaTrust Client Protected Data |
| gtf | Gene Transfer Format File |
