| gbp | Genesis Bitmap Pattern |
| gbs | Gerber Bottom Solder Mask Data |
| gbsdat | gBilling Server Data |
| gbx | Gerber PCB Data |
| gc | GraphClick File |
| gc2 | GENECLUSTER GC2 Output File |
| gc3 | GENECLUSTER GC3 Stage File |
| gcat | GUI Design Studio Catalogue File |
| gcb | Google Chrome Backup Archive |
| gcd | General CADD Drawing |
| gcd | Garmin Nuvi Software Update |
| gcf | GameExchange2 Camera Data |
| gcg | GCG DNA Sequence |
| gci | Gamecube Game Save |
| gcm | Gamecube Disk Image |
| gco | G-code Code |
| gcod | G-code Code |
| gcode | G-code Code |
| gcp | Spectramap Group Properties |
| gcrd | GnomeCard vCard Data |
| gct | GenePattern Gene Cluster Text |
| gctl | SCCM GIAM Control Data |
| gcw | Microsoft Mathematics Worksheet |
| gd | STK Database Update Information |
| gd1 | Gerber Drill Drawing Data |
| gd2 | Gerber Drill Drawing Data |
| gd3 | SNES ROM Image GD3 |
| gd3 | Gerber Drill Drawing Data |
| gdb | Genbox Family History Database |
| gdb | TIGER Geodatabase |
| gdd | Gerber Drill Drawing Data |
| gdi | Sega Dreamcast GDI Image |
| gdo | Gerber Data Object |
| gdt | Guitar and Drum Trainer Song |
| gdx | GAMS Data Exchange File |
