| g2n | FontForge Glyph to Name Map |
| g2p | CMU Sphinx G2P Model |
| g2r | Casio Prizm Main Memory Data |
| g2s | Garmin City Navigator Traffic Trends Data |
| g3 | Gerber Inner Routing Layer 1 Data |
| g3d | GOM 3D Data |
| g3drem | Dremel 3D20 Toolpath Data |
| g3e | Casio Prizm eActivity File |
| g3k | Casio Prizm Manager PLUS Key Log |
| g3l | Casio Prizm Add-in Language File |
| g3m | Casio Prizm Main Memory Data |
| g4 | Gerber Inner Routing Layer 1 Data |
| g5 | CAMtastic Mid Layer Gerber Data |
| g64 | Genetec Omnicast Video Archive |
| g8 | Cubicomp PictureMaker Green Channel Image Data |
| g99 | HEC-RAS Geometry File |
| ga | STK Great Arc Propagator File |
| ga3 | Graphical Analysis 3 Document |
| gaa | GAL-ANA Data File |
| gad | Intergado Data File |
| gad | GeoDict Analytic Data |
| gaf | GameExchange2 Animation |
| gai | Adobe Glyphlet Development Kit Glyphlet |
| gal | GenePix Array List |
| gal | Corel Multimedia Manager v6 Album |
| galleryitem | SMART Notebook Gallery Item |
| gam | General Game Data File |
| gam | Gamma Card Data |
| gam | Aureas Theme File |
| gaml | GAML Document |
| gap | Generation Analysis and Planning Data |
| gas | Grab-a-Site Data File |
| gasx | GOM Player Data |
| gat | GATTer Configuration Data |
| gb | Nintendo GameBoy ROM Image |