KAME racoon IKE daemon, ipsec-tools version

http://ipsec-tools.sourceforge.net/

High performance realtime 3D engine

http://irrlicht.sourceforge.net/

Modular IRC client with many features

https://irssi.org/

Collection of useful scripts for the irssi IRC-client

https://scripts.irssi.org/

Collection of additional irssi themes

https://irssi-import.github.io/themes/

Font by John Stracke based on the Isabella Breviary

https://www.thibault.org/fonts/isabella/

ISC Cron, former Vixie Cron

ftp://ftp.isc.org/isc/cron/

The ISC Dynamic Host Configuration Protocol client

https://www.isc.org/dhcp/

The ISC Dynamic Host Configuration Protocol relay

https://www.isc.org/products/DHCP/

ISC Dynamic Host Configuration Protocol server

https://www.isc.org/dhcp/

Lists of the country, language, and currency iso names

https://salsa.debian.org/iso-codes-team/iso-codes

Character entity sets from ISO 8879:1986 (SGML)

Make XML documents translatable through po files

http://itstool.org/

Online presence and instant messaging server

https://jabberd2.org/

Low latency audio server

https://jackaudio.org/

Object-oriented SGML/XML parser toolkit and DSSSL engine

http://www.jclark.com/jade/

JavaBeansTM Activation Framework

http://java.sun.com/products/javabeans/jaf/

High performance image processing libraries for Java

http://java.sun.com/products/java-media/jai/

Setuid version of jexec to allow normal users access to jails

https://github.com/Intermedix/jailme

Perl/awk/sh regular expressions for Java

https://jakarta.apache.org/oro/

Regular expressions for Java

http://jakarta.apache.org/regexp/

Apache Struts framework

http://struts.apache.org

Build utility like make(1)

http://www.perforce.com/jam/jam.html

Compact Java virtual machine

http://jamvm.sourceforge.net/

C library for encoding, decoding, and manipulating JSON data

http://www.digip.org/jansson/

Implementation of the codec specified in the JPEG-2000 standard

https://www.ece.uvic.ca/~frodo/jasper/

Updated Java timezone definitions

Just Journal for Java blogging app

https://www.justjournal.com/

Reference Implementation of JSR 919

https://javaee.github.io/javamail/

Wrapper script for various Java Virtual Machines

Java XPath Engine

https://jaxen.org

Decoder implementation of the JBIG2 image compression format

https://github.com/ArtifexSoftware/jbig2dec

Lossless compression for bi-level images such as scanned pages, faxes

https://www.cl.cam.ac.uk/~mgk25/jbigkit/

JDBC connection pool

http://www.bitmechanic.com/projects/jdbcpool/

Java library for accessing and manipulating XML documents

http://www.jdom.org/

Mainline variant of Kademlia Distributed Hash Table (DHT)

http://www.pps.univ-paris-diderot.fr/~jch/software/bittorrent/

Powerful programmer\x27s text editor written in Java

http://jedit.sourceforge.net/

Open-source continuous integration server

https://jenkins.io/

Free and open source typeface for developers

https://www.jetbrains.com/lp/mono

jf Open Huninn by justfont

https://justfont.com/huninn/

Simulates a jigsaw puzzle and illustrates the use of clipping paths

http://gap.nongnu.org/jigsaw/

Java source to byte-code compiler made available by IBM

http://jikes.sf.net/

Command line client for posting JustJournal entries

https://www.justjournal.com/

Jerry's command-line LiveJournal.com entry system

http://umlautllama.com/projects/perl/#jlj

Jim Knoble's font package for X

http://www.jmknoble.net/fonts/

Joe's Own Editor

https://sourceforge.net/projects/joe-editor/

Dynamic web content management system (CMS)

https://www.joomla.org/

IJG's jpeg compression utilities

http://www.ijg.org/

SIMD-accelerated JPEG codec which replaces libjpeg

https://libjpeg-turbo.org/

View and/or control a remote PC

http://jrdesktop.sourceforge.net/