| inl | Inspiration Custom Symbol Library |
| inmr | iNMR Data |
| inms | Adobe InDesign Menu Set |
| inn | Lumion Thumbnail |
| inp | WinUAE Input Recorder Data |
| inp | Abaqus/CAE Input Data |
| inpx | PTV Vissim Model |
| inq | EHR Meaningful Use Stage 2 Patient Inquiry Data |
| ins | Microsoft SMS Instructions |
| inst | RMCProfile Instrument Data |
| int | Tinker Internal Coordinates |
| int | STK Interval List File |
| int | Nostalgia Emulator Intellivision ROM |
| int | Gaussian Two-Electron Integral File |
| int | Molpro Permanent Integral Data |
| intlib | Altium Designer Integrated Library |
| inx | PCCharge Request XML File |
| in_ | Compressed INI File |
| iod | Sony DVGate IO Data |
| iof | FindIt Data Fle |
| iok | Omniscope IOK Data |
| iom | Bosch VisualMotion IO Mapper Data |
| iom | Omniscope IOM Data |
| ios | Apple iOS Related Data |
| iox | Response Channel Manager Template |
| ipalias | Apple iPhoto Alias File |
| ipc | IPC-D-356 Data |
| ipe | Microth InPad Stroke Set |
| ipf | F-Secure Incremental Policy File |
| ipf | IGOR Pro Procedure File |
| iphoto | Apple iPhoto Photo Library |
| ipi | Microsoft Windows Installer Data |
| iplb | Apple iPhoto Library File |
| ipm | Image-Pro Plus Macro |
| ipmeta | Apple iPhoto Metadata |
