| gradle | Android Studio Gradle Properties |
| grc | GX Compiled Resource File |
| grdecl | Eclipse ASCII Grid Data |
| grh | GX Resource Header File |
| grid | Eclipse Grid Data |
| grn | Granny 3D Document |
| groovy | Groovy Script |
| gs | Gofer Source Code |
| gsh | Visual Studio GL Shader Data |
| gshader | Visual Studio GL Shader Data |
| gsoap | gSOAP Settings |
| gsy | Green Shoes Package |
| gt | IBM WebSphere sMash Groovy Template |
| guess | Autotools Triplet |
| gvy | Groovy Script |
| gwe | GameWeaver Executable |
| gwf | Benthic Golden Data File |
| gwsp | Axeda Builder Project |
| gxp | Google XML Pages File |
| gxr | GeneXus Report |
| gyp | Chromium GYP Language File |
| gypi | Chromium GYP Language Include |
| h | C Header File |
| h2 | H2 Database File |
| h86 | µVision Intel HEX Data |
| hac | Helma Actions Script |
| hal | HansaWorld Hansa Applications Language File |
| ham | HAM Executable File |
| haml | Haml Source Code |
| handlebars | Handlebars Template |
| has | Haskell Script |
| hbs | Handlebars Template |
| hcf | Compact HAM Library |
| hdcl | Hierarchical Dynamic Composition Language Document |
| hdmp | Windows Heap Dump |