| hxc | MS Help 2 Project Collection Definition |
| hxe | MS Help 2 Project Sample Definition |
| hxf | MS Help 2 Project Include File |
| hxk | MS Help 2 Project Index |
| hxml | Haxe Compiler Options |
| hxt | MS Help 2 Project ToC |
| hxv | MS Help 2 Project Virtual Topic Definition |
| hxx | C++ Header File |
| hydra | Hydra Image Filter Program |
| hzx | CrossWorks for ARM Linked Executable |
| i | IAR System Preprocessed Source Data |
| i | INTERCAL Source File |
| i | Visual C++ Preprocessed Source |
| i3 | Modula-3 Interface Source Code |
| i6 | Inform 6 Source Code |
| i64 | Interactive Disassembler Data |
| i6t | Inform 6 Template |
| i7 | Inform 7 Source Code |
| i7x | Inform 7 Extension Source Code |
| ian | COOL:Jex Business Team Model |
| iap | Infinity Engine Add-on Patcher File |
| ibplugin | Interface Builder Plug-in |
| ib_mon | IncrediBuild Build Progress Data |
| ic | Esterel Intermediate Code |
| ic | µVision Intermediate C Source Code |
| icf | Implementation Configuration File |
| icfg | Aristotle Interprocedural Control Flow Graph |
| ici | ICI Source Code |
| icp | Remote Call Profiler Data |
| icu | ICU Data |
| icz | Lib2Def Output File |
| id0 | IDA Database |
| id1 | IDA Database |
| ida | Internet Data Administration Script |
| idapi | Borland Database Engine IDAPI Data |
