| imiss | PLINK Individual-based Missing Data Report |
| imk | IncrediMail License Key |
| imn | IncrediMail Notifier |
| imotion | iClone Motion Capture Data |
| imovielibrary | iMovie Library Data |
| impx | Bentley Map Import XML Data |
| imr | Inertial Explorer IMU Data |
| imu | Inertial Explorer Waypoint IMU Raw Data |
| imw | IncrediMail Sound File |
| in4 | InfoBlaster IN4 Data |
| in7 | OxMetrics Human-readable Data |
| ina | MS-DOS Data |
| inb | Delft3D Initial Bed Composition Data |
| inc | POV-Ray Include File |
| incl | BBEdit Markup Include |
| ind | Maple Repository Index File |
| ind | LaTeX Processed Index Data |
| ind | TINA Library Index |
| ind | SQL Script Indexes |
| index | MySQL Binlog Index File |
| index | DICT Index File |
| indk | Adobe InDesign Keyboard Shortcut Set |
| inds | Adobe InDesign Snippet |
| indx | CALDB Index |
| inetloc | Mac OS X Finder Internet Location |
| info | Spider File Storage Index |
| inf_loc | Windows Driver Information Cache File |
| ing | MasterCook Ingredients Data |
| inj | DAZ Studio 3D Morph Injection Data |
| ink | Tablet PC Digital Ink |
| inl | Inspiration Custom Symbol Library |
| inlx | Adobe InDesign Interchange Library |
| inmr | iNMR Data |
| inms | Adobe InDesign Menu Set |
| inn | Lumion Thumbnail |