| graphml | GraphML Document |
| graphmlz | GraphML Compressed Document |
| grf | GEM Graph Document |
| grf | Grapher Document |
| grg | GreatFamily Graphic Gallery |
| grs | Esko Packedge GRS Document |
| gsa | Microsoft Office Groove 2007 Archived Workspace |
| gsb | Grisbi Document |
| gsd | Profibus Generic Station Description |
| gsh | GenStat Spreadsheet |
| gsheet | Google Drive Sheet |
| gslides | Google Drive Presentation |
| gsp | Sketchpad Document |
| gstencil | OmniGraffle Stencil |
| gsw | GraphShow Worksheet |
| gta | Microsoft Office Groove 2007 Archive |
| gtc | Graitec Exchange Format Document |
| gtcx | Graitec Exchange Format Document |
| gtemplate | OmniGraffle Template |
| gtp | Guitar Pro Tabulature |
| gtt | Guntrams Tabletweaving Thingy Pattern |
| guide | Amigaguide Hypertext Document |
| gul | JungUm Global Document |
| gv | Graphviz DOT File |
| gvdesign | Gravit Designer Document |
| gwb | GenStat Book |
| gwk | GraphiCode PCB Job |
| gx | Geometry Expressions Document |
| gxd | General CADD Pro Drawing |
| han | Headline Studio Animation |
| hbl | Braille Sense Format File |
| hcdx | Hallmark Card Studio Document |
| hdd | HotDisc Designer Document |
| hdm | Handheld Device Markup Language |
| hdml | Handheld Device Markup Language |