| gbk | Wiley eGrade Gradebook |
| gbl | Genesis Bitmap Layout |
| gbl | Gerber Bottom Layer Data |
| gbn | OASIS Montaj Binary Data |
| gbo | Gerber Bottom Overlay Data |
| gbp | Genesis Bitmap Pattern |
| gbp | Gerber Bottom Paste Mask Data |
| gbs | Gerber Bottom Solder Mask Data |
| gbsdat | gBilling Server Data |
| gbts | eXtendable Wad Editor GBTS Data |
| gbv | GearBunny Data |
| gbw | Gerbview Workspace Data |
| gbx | Gerber PCB Data |
| gbx | Great Budget Budget Data |
| gbz | Prizoop Compressed ROM Image |
| gc | GraphClick File |
| gc | Sierra Print Artist Greeting Card |
| gc2 | GENECLUSTER GC2 Output File |
| gc3 | GENECLUSTER GC3 Stage File |
| gcat | GUI Design Studio Catalogue File |
| gcb | Google Chrome Backup Archive |
| gcc | Gene Construction Kit Data |
| gccv | Adobe PageMaker GCCV Filter Data |
| gcd | Garmin Nuvi Software Update |
| gcd | General CADD Drawing |
| gcd | Mercury Refcode List Data |
| gcd | Microsoft SharePoint WorkSpace Groove Component Download |
| gcf | GameExchange2 Camera Data |
| gcg | GCG DNA Sequence |
| gci | Gamecube Game Save |
