| ief | iCE CFR Raw Data |
| ief | ISIS Control File |
| iei | Image Eye Index Cache |
| iel | ParticleIllusion SE Emitter Library |
| iem | Informix Error Message |
| ienv | iData 3 Envelope Template Data |
| ies | IESNA Photometric Data |
| ie_ | Compressed IEC File |
| if90 | Programmer's Notepad Data |
| ifaith | iFaith SHSH Data |
| ifc | Industry Foundation Classes Data |
| ifczip | Compressed IFC Data |
| iff | SmartWare Temporary Merge Data |
| ifi | inFlow Inventory Database Backup |
| ifiction | Zoom iFiction File |
| ifl | Autodesk 3D Studio Max Image File List |
| iflv | InfoLevin Database |
| ifm | Brighterion iPrevent Fraud Model |
| ifm | RSView Machine Edition Information Message |
| ifm | Shana Informed Filler Form Data |
| ifn | IGOR Pro Formatted Notebook File |
| ifo | ImageForge Pro Graphic Object Layer Data |
| ifo | RSView Machine Edition Information Setup Data |
| ifol | Instant File Opener Data |
| ifp | KnowledgeMan Script |
| ifs | Ant Movie Catalog Script |
| ifs | FractInt IFS File |
| ifs | InfoSlips Package |
| ifs | OS/2 Warp Installable Filesystem Data |
| ift | BSL Inverse Fourier Transform Data |
| ift | IGOR Pro Formatted Notebook Template File |
| ifw | INTUS Terminal Firmware |
| ig | iSpy Event Data |
| igb | Google Earth Model File |
| igc | Anime List Builder Data |
