| gcl | GNU Common Lisp Source Code |
| gcna | Gcov Compiled Output |
| gcno | Gcov Metadata File |
| gcob | TRANSFER Cobol Source Code |
| gcov | GNU GCOV Logfile |
| gcr | GlowCode Profiling Results |
| gdb | Embarcadero InterBase Database File |
| gdt | Graph Drawing Toolkit Output |
| gek | GECK/Papyrus Script Editor Script |
| gemspec | RubyGems Gem Specification |
| gex | GameMaker Studio Extension |
| gf | Grammatical Framework Source |
| gfa | GFA BASIC Tokenized Source |
| gfar | Greenfoot Scenario Archive |
| gfe | Grammatical Framework Example |
| gfm | GitHub Flavored Markdown Document |
| gfo | Grammatical Framework Object |
| gfs | Grammatical Framework Script |
| gfx | The Games Factory Extension |
| ggfx | FactoryTalk View Studio Global Object Display Component File |
| ghc | Adobe RoboHelp Visual Basic Constant Map |
| gitattributes | Git Attributes |
| gitignore | Git Ignore File |
| gld | MPLAB C Compiler Linker Script |
| glnk | TRANSFER Linkage Definitions |
| glo | Visual Basic Global Declaration |
| global | Global Makefile |
| gls | GLScript Game Script |
| glsl | OpenGL Shading Language File |
| gm6 | Game Maker 6.x Data |
| gm81 | Game Maker 8.1 Data |
| gmd | Game Maker 4.x Data |
| gmdb | GMap.NET Database |
| gmez | GameMaker Studio Extension |
| gmf | Game Maker 3.x Data |