| gcx | Macintosh Grapher Document |
| gdb | SmartWare Business Graph Definition File |
| gdc | SmartWare Composite Graph Definition File |
| gdc | Iconics GraphWorx32 Display for WinCE |
| gde | SmartWare Elevation Graph Definition File |
| gde | The Guide Document |
| gdf | Iconics GraphWorx32 Display |
| gdh | SmartWare High-Low Graph Definition File |
| gdl | ArchiCAD Geometric Description Language File |
| gdn | SmartWare Graph Definition File |
| gdoc | Google Drive Document |
| gdraw | Google Drive Drawing |
| gds | SmartWare Scientific Graph Definition File |
| gds | GDSII Document |
| gds2 | GDSII Document |
| gdsii | GDSII Stream Data |
| gdt | SmartWare Text Graph Definition File |
| ged | GEDCOM Document |
| gedcom | GEDCOM Document |
| gen | GenStat Command File |
| geo | Carbon Graphics Geo Data File |
| ger | Readme Text |
| gerber | Gerber Format Document |
| gev | GelEval for Mac Document |
| gevl | GelEval for Mac Document |
| gfc | Patton & Patton Flow Charting 4 Document |
| gfd | GNUe Form Definitions |
| gform | Google Drive Form |
| ggb | GeoGebra Document |
| ggg | Green Globs & Graphing Equations Document |
| ggt | GeoGebra Tool |
| gh | Grasshopper 3D Document |
| ghx | Grasshopper 3D XML Document |
| gib | Graph-in-the-Box Chart |
| gid | Windows Global Index File |