| ileaf | Interleaf Desktop |
| ilf | Alim Data File |
| ilg | LaTeX Index Generation Log |
| ilht | Mac OS X Finder Internet HTTP Location |
| ilib | ClarisDraw Art Library |
| ilm | MotionTracking Illumination Correction Data |
| ilo | HP ILO Recorded Console Session |
| ilp | Gurobi Optimizer Temporary Data |
| ilr | Unity License Request File |
| ils | RFM Instrument Line Shape File |
| ilt | SpectrILight III Saved Spectrum Binary Data |
| ilx | Interlex Vocabulary Data |
| im | Wild Magic 5 Image Data |
| im4m | IMG4 Signature Data |
| im4p | IMG4 Payload Data |
| ima | Zemax Image Surface Data |
| imap | IceWarp Mail Server IMAP Data |
| imb | IncrediMail Address Book |
| imd | Integration Manager Database |
| ime | IncrediMail Emotions Data |
| imesx | Microsoft Office IME Search Provider Definition |
| imf | IncrediMail Letter File |
| img | Magellan eXplorist Map Image |
| img3 | Apple iPhone IMG3 Data |
| img4 | Apple iPhone IMG4 Data |
| imh | IncrediMail Contacts Export Data |
| imi | Magellan eXplorist Map Image |
| imiss | PLINK Individual-based Missing Data Report |
| imk | IncrediMail License Key |
| immodules | GTK+ Input Method Modules Data |
| imn | IncrediMail Notifier |
| imotion | iClone Motion Capture Data |
| imovielibrary | iMovie Library Data |
| impx | Bentley Map Import XML Data |
| imr | Inertial Explorer IMU Data |