Alphabetically: J
Extension File Description File Type
.j
Java Source File
Developer
.j2c
JPEG 2000 Code Stream
Raster Image
.j2i
Jazz 2 Internet Link File
Game
.j2k
JPEG 2000 Image
Raster Image
.j2l
Jazz Jackrabbit 2 Level File
Game
.jad
Java Application Descriptor File
Misc
.jam
PS3 Unreal Tournament 3 Mod File
Game
.jar
Java Archive File
Executable
.jar.pack
Pack200 Packed Jar File
Compressed
.jas
Cheetah3D Model File
3D Image
.jasper
JasperReports Data File
Data
.jav
Java Source File
Developer
.java
Java Source Code File
Developer
.jb2
JBIG2 Image
Raster Image
.jbf
Paint Shop Pro Browser Cache File
Raster Image
.jbi
Motoman Robot Job File
Data
.jbig
Joint Bi-level Image Group File
Raster Image
.jbk
Juno Backup File
Backup
.jbmp
JAmes OS Bitmap Image
Raster Image
.jbr
Paint Shop Pro Brushes File
Raster Image
.jc
FlashGet Partial Download
Misc
.jc!
FlashGet Incomplete Download
Misc
.jcz
Liquid Motion Animation
Web
.jdb
Symantec Endpoint Protection Update File
Data
.jdc
JDownloader Links File
Backup
.jdf
Adobe Acrobat Job Definition File
Settings
.jed
Xilinx JEDEC Programming File
Developer
.jef
Janome Embroidery Format
Data
.jfi
JPEG File Interchange Image
Raster Image
.jfif
JPEG File Interchange Format
Raster Image
.jg4
BigJig Jigsaw Puzzle
Game
.jgz
Gzipped Javascript File
Compressed
.jhtml
Java HTML Web Page
Web
.jia
Digital Photo Navigator Album
Raster Image
.jic
Java Icon File
Compressed
.jif
JPEG Image File
Raster Image
.jiff
JPEG Image File Format
Raster Image
.jis
Japanese Industry Standard Text
Text
.jmp
JMP Data File
Data
.jng
JPEG Network Graphic
Raster Image
.jnlp
Java Web Start File
Web
.jnt
Windows Journal File
Data
.job
Windows Task Scheduler Job File
System
.joboptions
Adobe Joboptions File
Data
.joined
HJ-Split Data File
Data
.jp1
Japanese (Romaji) Text File
Text
.jp2
JPEG 2000 Core Image File
Raster Image
.jpc
JPEG 2000 Code Stream File
Raster Image
.jpd
Java Process Definition
Developer
.jpe
JPEG Image
Raster Image
.jpeg
JPEG Image File
Raster Image
.jpf
JPEG 2000 Image
Raster Image
.jpg
JPEG Image File
Raster Image
.jph
JProbe Memory Snapshot
Data
.jpr
JBuilder Project
Developer
.jps
Stereo JPEG Image
Raster Image
.jpw
World File for JPEG
GIS
.jpx
JPEG 2000 Image File
Raster Image
.jrprint
JasperReports Print File
Data
.jrs
Exchange Reserve Transaction Log File
Misc
.jrtf
JAmes OS Rich Text File
Text
.jrxml
JasperReports Layout File
Data
.jrz
PSP Game Data File
Game
.js
JavaScript File
Web
.jse
JScript Encoded File
Executable
.jsf
Project64 Joystick File
Settings
.jsfl
Flash JavaScript File
Developer
.json
JavaScript Object Notation File
Developer
.jsp
Java Server Page
Web
.jspa
Java Servlet Alias
Web
.jspx
XML Java Server Page
Web
.jst
JavaServer Page Document
Web
.jsx
ExtendScript Script File
Executable
.jsxbin
Binary ExtendScript Script File
Plugin
.jsxinc
ExtendScript Included Script File
Developer
.jt
JT Open CAD File
CAD
.jtf
JPEG Tagged Interchange Format
Raster Image
.jtp
Windows Journal Template
Layout
.jts
Cyberlink AVCHD Video File
Video
.jude
JUDE Project File
Data
.jvs
JavaScript Proxy Autoconfig File
Web
.jvsg
Video Surveillance Project
CAD
.jwl
Roxio Jewel Case File
Raster Image
.jws
Java Web Services File
Web
.jxr
JPEG XR Image
Raster Image