| 1 | I | Microsoft | Visual Studio Intermediate Format |
| 2 | I00 | DVD Shrink | DVD Shrink Part 1 Format |
| 3 | I01 | DVD Shrink | DVD Shrink Part 2 Format |
| 4 | I02 | DVD Shrink | DVD Shrink Part 3 Format |
| 5 | I03 | N/A | Split Disk Image |
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| 6 | I04 | Freeware | Split Disk Image |
| 7 | I05 | N/A | Split Disk Image |
| 8 | I3PACK | Zepetto | Point Blank Game Data Format |
| 9 | IAF | Microsoft | Outlook Internet Account Format |
| 10 | IAI | N/A | Nova Logic Item Attributes Info |
| 11 | IAM | Autodesk | Inventor Assembly Format |
| 12 | IBD | Oracle Corporation | MySQL InnoDB Database Table |
| 13 | IBI | Raven Software | Raven Software ICARUS Compiled Script |
| 14 | IBOOK | N/A | Generic |
| 15 | IBOOKS | Apple | Multi-Touch IBook |
| 16 | IBZ | Oracle Corporation | MySQL InnoDB Database Table Compressed Backup |
| 17 | ICA | Citrix | Citrix ICA Format |
| 18 | ICB | Avid Technology | Targa ICB Bitmap Image |
| 19 | ICC | International Color Consortium | ICC Profile |
| 20 | ICL | Microsoft | Windows Icon Library Format |
| 21 | ICM | N/A | Image Color Matching Profile |
| 22 | ICMA | Adobe Systems | InCopy Assignment Format |
| 23 | ICML | Adobe Systems | InCopy Document |
| 24 | ICMT | Adobe Systems | InCopy Template |
| 25 | ICN | N/A | Windows Icon Format |
| 26 | ICNS | Apple | Mac OS X Icon Resource Format |
| 27 | ICO | Microsoft | Icon Format |
| 28 | ICON | N/A | Icon Image Format |
| 29 | ICONTAINER | Panic | CandyBar IContainer Format |
| 30 | ICS | Internet Engineering Task Force | ICalendar Format |
| 31 | ICTE | Apple, Inc. | Apple Mac Internet Configuration |
| 32 | ICXS | Apple, Inc. | ITunes |
| 33 | ID | IBM | Lotus Notes User ID Format |
| 34 | ID31 | Intermedia Software | Helium Music Manager Id3 Tags Export |
| 35 | ID32 | Intermedia Software | Helium Music Manager Id3 Tags Export |
| 36 | IDAP | Adobe Systems | Adobe InDesign Assignment Package |
| 37 | IDB | Microsoft | Visual Studio Intermediate Debug Format |
| 38 | IDC | Microsoft | Internet Database Connector Format |
| 39 | IDD | N/A | Adobe InDesign For Mac Document |
| 40 | IDEA | Adobe Systems | Adobe Ideas Document |
| 41 | IDLK | Adobe Systems | Adobe InDesign Lock Format |
| 42 | IDML | Adobe Systems | Adobe InDesign Markup Language Format |
| 43 | IDPK | Adobe Systems | Adobe InDesign Package For GoLive Format |
| 44 | IDRAW | N/A | iDraw vector graphics |
| 45 | IDRC | Adobe Systems Incorporated | Adobe InDesign Resource |
| 46 | IDS | BioWare | Infinity Game Engine |
| 47 | IDT | Microsoft | Windows Installer Database Text Archive Format |
| 48 | IDX | The VobSub Team | Index Format |
| 49 | IEBARZIP | N/A | Explorer Bar Icon Pack |
| 50 | IES | Illuminating Engineering Society | IES Photometric Data Format |
| 51 | IF | Procedimientos-Uno | Procedimientos-Uno IFWin Project Format |
| 52 | IFC | BuildingSMART | Industry Foundation Classes Format |
| 53 | IFD | Fly Software | InForm Document |
| 54 | IFF | Electronic Arts | Interchange Format |
| 55 | IFO | N/A | DVD-Video Disc Information Format |
| 56 | IFP | Rockstar Games | GTA Animation Format |
| 57 | IFT | N/A | Canon Settings |
| 58 | IFV | N/A | Indeo Video Format |
| 59 | IGA | CARIS | CARIS GIS Corner Georeferencing Coordinate |
| 60 | IGES | N/A | IGES Format |
| 61 | IGO | Facebook, Inc. | Instagram JPEG Picture Image |
| 62 | IGS | N/A | IGES Drawing Format |
| 63 | IGY | Microsoft Corporation | Microsoft Excel Web Query |
| 64 | IHTML | N/A | Inline HyperText Markup Language |
| 65 | II | Axialis Software | IconWorkshop Extended Information Format |
| 66 | IIF | Intuit | Intuit Interchange Format |
| 67 | IIL | N/A | CleanSweep Installation Log |
| 68 | IIQ | Phase One | Phase One RAW Image |
| 69 | IM | Sun Microsystems, Inc. | SunOS Grey Scale Bitmap |
| 70 | IMA | N/A | Generic Disk Image |
| 71 | IMC | LucasArts Entertainment Company, LLC | LucasArts Game Sound |
| 72 | IMF | id Software | Id Music Format |
| 73 | IMG | Apple | Macintosh Disk Image |
| 74 | IMG3 | Apple | IPhone IMG3 Format |
| 75 | IMZ | Gilles Vollant | WinImage Compressed Disk Image |
| 76 | INC | N/A | Include Format |
| 77 | INCP | Adobe Systems | InCopy CS3 Package Format |
| 78 | IND | Adobe | Adobe InDesign Graphics Document Format |
| 79 | INDB | Adobe Systems | Adobe InDesign Book Format |
| 80 | INDD | Adobe Systems | Adobe InDesign Document |
| 81 | INDESIGNPLUGIN | Adobe Systems | Adobe InDesign Plug-in |
| 82 | INDEX | The Eclipse Foundation | Eclipse Help Index |
| 83 | INDEXARRAYS | Apple, Inc. | Mac OS X Spotlight |
| 84 | INDEXCOMPACTDIRECTORY | Apple, Inc. | Mac OS X Spotlight |
| 85 | INDEXDIRECTORY | Apple, Inc. | Mac OS X Spotlight |
| 86 | INDEXPOSITIONS | Apple, Inc. | Mac OS X Spotlight |
| 87 | INDEXPOSITIONTABLE | N/A | Mac OS X Spotlight |
| 88 | INDL | Adobe Systems | Adobe InDesign Library |
| 89 | INDP | Adobe Systems | Adobe InDesign CS3 Package Format |
| 90 | INDT | Adobe Systems | Adobe InDesign Template |
| 91 | INETLOC | N/A | Internet Location |
| 92 | INF | N/A | Setup Information Format |
| 93 | INI | N/A | Windows Initialization Format |
| 94 | INI2 | N/A | Text Configuration |
| 95 | INIX | Adobe Systems Incorporated | Adobe InDesign |
| 96 | INL | Microsoft | C++ Inline Format |
| 97 | INLK | Adobe Systems | Adobe InDesign Lock Format |
| 98 | INMS | Adobe Systems | Adobe InDesign Menu Set Format |
| 99 | INPROGRESS | Apple | Time Machine Backup Progress Format |
| 100 | INPUTPLUGIN | Apple, Inc. | Apple Mac OS X PluginIM Input Method |
| 101 | INSS | Apple, Inc. | Apple Mac OS X Setup Assistant ISP Info Document |
| 102 | INSTALLHELPER | Apple, Inc. | Apple Mac OS X Install Helper Document |
| 103 | INSTALLLOG | Microsoft Corporation | Microsoft .NET Installation Log |
| 104 | INSTALL_BACKUP | AVG Technologies (Grisoft) | AVG Shell Extension Module |
| 105 | INTERNETCONNECT | Apple | Apple Internet Connect Document |
| 106 | INTU | Intuit Inc. | Quicken For Mac |
| 107 | INUSE | N/A | Text Configuration Format (in Use) |
| 108 | INX | Adobe Systems | Adobe InDesign Interchange Format |
| 109 | ION | N/A | File Description Format |
| 110 | IOS | N/A | Generic |
| 111 | IP | Stardock | IconPackager Theme Format |
| 112 | IPA | Apple, Inc. | IPhone Application |
| 113 | IPB | N/A | IPhone Perl Script |
| 114 | IPCC | Apple | IPhone Carrier Bundle |
| 115 | IPCH | Microsoft | Intellisense Precompiled Header Format |
| 116 | IPD | Research In Motion | BlackBerry Backup Format |
| 117 | IPG | Apple | IPod Game Format |
| 118 | IPSW | Apple | IPod And IPhone Software Update Format |
| 119 | IPSX | N/A | iPhone firmware update |
| 120 | IPT | Autodesk | Inventor Part Format |
| 121 | IPTHEME | Stardock | IconPackager Raw Theme Format |
| 122 | IPUTILS | The GNOME Project | Gnome Desktop |
| 123 | IPX | Minds-Eye-View | IPIX Image |
| 124 | IPZ | ICQ LLC | ICQ Plus Skin |
| 125 | IQY | Microsoft | Internet Query |
| 126 | IRB | N/A | VarioCAM thermogram |
| 127 | IRBRC | Ruby community | Ruby |
| 128 | IREV | RunRev Ltd. | Runtime Revolution Script |
| 129 | IRF | iVIEW Technology | Autodesk Impression Drawing Format |
| 130 | IROS | Adobe Systems | Adobe Save For Web Settings Format |
| 131 | IRRMESH | N/A | Irrlicht Static Mesh |
| 132 | IRS | Adobe Systems | Adobe Save For Web Settings |
| 133 | ISA | Adobe Systems Incorporated | Adobe Photoshop ImageReady Action |
| 134 | ISB | Sony Online Entertainment | Vanguard Music |
| 135 | ISMV | Microsoft | IIS Smooth Streaming Video Format |
| 136 | ISO | International Organization for Standardization | Disc Image Format |
| 137 | ISP | Microsoft | IIS Internet Service Provider Settings |
| 138 | ISWP | Apple, Inc. | Apple ITunes IOS Firmware Update |
| 139 | ISX | Intrasis | Intrasis Object |
| 140 | ISZ | EZB Systems | Zipped ISO Disk Image |
| 141 | ITA | Joost Verburg | IconTweaker Theme Archive |
| 142 | ITC2 | Apple | ITunes Cover Flow Data Format 2 |
| 143 | ITDB | Apple | ITunes Database Format |
| 144 | ITG | Intergraph Corporation | Intergraph Format Bitmap Graphics |
| 145 | ITHMB | Apple | IPod And IPhone Photo Thumbnails Format |
| 146 | ITI | Jeffrey Lim | Impulse Tracker Instrument |
| 147 | ITL | Apple | ITunes Library Format |
| 148 | ITLP | Apple | ITunes LP Album Format |
| 149 | ITLS | Apple | ITunes Live Stream URL |
| 150 | ITM | isee systems | IThink Model Format |
| 151 | ITMS | Apple | ITunes Music Store Link Format |
| 152 | ITMSP | Apple | ITunes Store Package |
| 153 | ITMX | N/A | XMILE XML Model Interchange Language |
| 154 | ITMZ | Craig Scott | IThoughtsHD Mind-map Document |
| 155 | ITP | BioWare | BioWare Aurora Game Engine Palette |
| 156 | ITPC | Apple | ITunes Podcast Link Format |
| 157 | ITS | Jeffrey Lim | Impulse Tracker Sample |
| 158 | ITSS | N/A | Generic |
| 159 | ITXIB | Apple, Inc. | Apple ITunes Dump |
| 160 | IV | Visualization Sciences Group | Open Inventor Scene Graph Format |
| 161 | IVE | OSG Community | OpenSceneGraph Binary Format |
| 162 | IVF | Intel | Indeo Video Format |
| 163 | IW4 | N/A | DjVu Image Format |
| 164 | IW44 | N/A | DjVu Image Format |
| 165 | IWA | Apple | iWork Archive File |
| 166 | IWB | SMART Technologies ULC | Common Format |
| 167 | IWD | Activision | Call Of Duty Game Data Format |
| 168 | IWI | Activision | Infinity Ward Texture Format |
| 169 | IWS | JetBrains | Trojan-Downloader.JS.Agent Format |
| 170 | IXB | Corel | Ulead Disc Image |
