| grd | Zemax Profile Data |
| grdb | GRAMPS Database |
| gre | GRETEP Data |
| greenshot | Greenshot Data |
| grf | Insight II Standard Graph Definition |
| grfx | GraphStudioNext XML Graph Data |
| grh | ILWIS Graphs Data |
| gri | Petrosys Grid Data |
| grib | Gridded Binary Data |
| grib2 | Gridded Binary v2 Data |
| grid | GridMove Grid Template |
| grind | Juice Grinder Recipe Data |
| grindx | Juice Grinder Recipe Data |
| grk | Gradekeeper Class Gradebook |
| grldr | GRUB4DOS Internal Loader Data |
| grm | PLINK GCTA Text Relationship Matrix |
| group | Unix Filesystem Group Quota Data |
| groups | WebMoney Keeper CLASSIC Group Data |
| grov | Reason Regroove Data |
| growlregdict | Growl Registration Ticket Data |
| growlticket | Growl Notification Data |
| grp | BPM Studio Playlist Archive |
| grp | ENVI Display Group Data |
| grp | GameExchange2 Scene List |
| grp | GenePattern Gene Set Group File |
| grph | GRPH Data File |
| grr | Gradekeeper Class Roster |
| grs | Getright Skin |
| grt | Grapher Template |
| grt | MegaHAL Greeting Data |
| gru | FXpansion GURU Preset |
| grv | CART Grove Data |
| grv | Microsoft Office Groove File |
| grv | PTC Creo Mill Grooving Parameter Data |
| grx | Getright Exported List |
