| imtx | iMindMap Template File |
| imx | iMindMap 5 Exported Document |
| inca | Adobe InCopy CS3 Assignment File |
| incd | Adobe InCopy 2.0 Document |
| inct | Adobe InCopy CS3 Template |
| incx | Adobe InCopy Interchange Document |
| indb | Adobe InDesign Book |
| indl | Adobe InDesign Library |
| indn | Adobe InDesign for Mac Document |
| indt | Adobe InDesign Template |
| info | GNU Info Document |
| infopathxml | Microsoft InfoPath XML Form |
| inld | ImageNow Document Link |
| inm | Caere FaxMaster Fax |
| inp | InPage Urdu Document |
| inpage | InPage Urdu Document |
| insx | InScribe XML Document |
| intaglio | Intaglio Drawing |
| iob | TurboSilver 3D Object |
| ion | Archive Description |
| ior | Maxwell Render Index of Refraction Data |
| ipdoc | InPrint 3 Document |
| ipf | Intercept Part File |
| ipn | Autodesk Inventor Presentation |
| ipt | Autodesk Inventor Part |
| ipv | iCAD Professional Document |
| ipw | UniPlot Graph |
| iqy | Microsoft Excel Web Query |
| iri | IRT Cronista Infrared Image |
| irr | Irrlicht 3D Scene |
| irrmesh | Irrlicht 3D Static Mesh |
| is2 | IRT Cronista Infrared Image |
| isdoc | Information System Document |
| isf | Inspiration Concept Map Document |
| isf | Intercept Symbol File |