| inprogress | Time Machine Backup Progress Data |
| inpx | PTV Vissim Model |
| inq | EHR Meaningful Use Stage 2 Patient Inquiry Data |
| inrs | Adobe InDesign for Mac Resource Data |
| ins | InstallShield Script |
| ins | Microsoft SMS Instructions |
| ins | SHELX Instructions Data |
| insp | Microsoft Visual Studio Inspector Data |
| inst | Geomview Transformed Instance Data |
| inst | RMCProfile Instrument Data |
| install | Microsoft Expression Web PHP Script |
| int | Gaussian Two-Electron Integral File |
| int | Molpro Permanent Integral Data |
| int | Nostalgia Emulator Intellivision ROM |
| int | STK Interval List File |
| int | Tinker Internal Coordinates |
| int | Zemax Interferometric Measurement Data |
| integers | ScadaWorks Integer Bank Template |
| interface | Notepad++ Interface Data |
| intlib | Altium Designer Integrated Library |
| intu | Intuit Quicken for Mac Data |
| inx | InstallShield Compiled Rules |
| inx | PCCharge Request XML File |
| in_ | Compressed INI File |
| iobit | Advanced SystemCare Rollback Data |
| ioc | Cadence Input-output Connectors Data |
| iod | Sony DVGate IO Data |
| iof | FindIt Data Fle |
| iok | Omniscope IOK Data |
| iokit | Dell DPACK Results Data |