| isx | ESI ITI SimulationX Project |
| itp | ITEM ToolKit Project |
| iveproj | Investigation Video Editor Project |
| ivg | VisualAge RPG Project File |
| iwp | Website X5 Project |
| iwprj | Incomedia Website X5 Project |
| iwz | InstallShield Wizard Project |
| iyp | Instyler Project |
| izz | Isadora Media Control Project |
| izzy | Isadora Media Control Project |
| jab | JAABA Project |
| jascproject | Paint Shop Pro Photo Album Project |
| jbp | DJ Jukebox Project |
| Jabaco Project |
| jcc | Code Crusader Project |
| jclic | JClic Project |
| jcp | JCreator Project |
| jdp | BlackBerry JDE Application Project |
| jdv | JDEVS Project |
| jed | JED Editor Project File |
| jep | jEPlus Project |
| jex | JExpress Project |
| jfp | OnScale Designer Project |
| jfproj | Microsoft Font Maker JSON Font Project |
| jfpx | OnScale Designer Exported Project |
| jlg | JoomLeague Project |
| jms | Hot Potatoes Masher Project |
| job | Kodak Preps Project |
| jpr | JBuilder Project |
| Oracle JDeveloper Model Project |
| jpx | Borland Together Implementation Project |
| JBuilder Project |
| jsl | Visual J# Project |
| jsproj | Visual Studio JavaScript Project |
| jude | JUDE Project |
| juth | JUDE Think! Project |
| jvsg | JVSG Video Surveillance Project |
| jws | JOC Web Spider Project |
| k3b | K3b Disk Burning Project |
| kaw | Karma Authoring Tool Workspace |
| kcp | knitCompanion Project |
| kdenlive | Kdenlive Project File |
| kin | Cakewalk Kinetic Music Project |
| kitsp | KIT Scenarist Project |
| kkd | K Kitchen Disk Project |
| kkf | Kaleidoscope Kreator Workspace |
| klp | CLIP Project Terminal-strip Project |
| kmproject | KineMaster Project |
| knxproj | KNX ETS Project |
| kpb | AMX KeypadBuilder Project |
| kpf | Komodo IDE Project |
| kpj | Keyman Developer Project |
| kpr | Kwalitan Project |
| kproj | Microsoft Visual Studio ASP.NET vNext Project |
| kpt | Kolor Panotour Project |
| kristal | KRISTAL Audio Engine Project |
| ktn | KTooN Animation Project |
| ktz | Kahootz Project |
| l4p | Lookout Direct Project |
| laz | LiquidApps Project |
| lb | Lens Blur Project |
| lbl | Creatacard Label Project |
| lbrn | LightBurn Project |
| lbrn2 | LightBurn v2 Project |
| lcd | LeoCAD Project |
| lcpp | Adobe Lens Profile Creator Project |
| ldz | Visual Studio DSM Project |
| let | Creatacard Letterhead Project |
| lfpackage | LumaFusion Project Package |
| lfx | Land F/X Project |
| lh3d | Live Home 3D Project |
| lhzd | Live Home 3D Compressed Project |
| library | CODESYS v3 Library Project |
| lightkeyproj | Lightkey Project |
| lil | lil Framework Project |
| liprj | LiDAR360 Project |
| lma | Learning Mobile Author Project |
| lmnr | Luminar 2018 Project |
| lmp | VB Language Manager Pro Binary Project |
| lnp | LOGO!Soft Comfort Network Project |
