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/

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/

Convert JIS Kanji to GuoBiao Hanzi

English to Japanese dictionary for GNUstep

http://www.eskimo.com/~pburns/Dictionaries/

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

Japanized ls

Jim Knoble's font package for X

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

MTP device filesystem

https://github.com/kiorky/jmtpfs

Java access to native shared libraries

https://github.com/twall/jna

Joe's Own Editor

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

Dynamic web content management system (CMS)

https://www.joomla.org/

SIMD-accelerated JPEG codec which replaces libjpeg

https://libjpeg-turbo.org/

Lightweight and flexible command-line JSON processor

https://stedolan.github.io/jq/

View and/or control a remote PC

http://jrdesktop.sourceforge.net/

Implementation of Ruby Interpreter in Pure Java

http://jruby.org/

JSON (JavaScript Object Notation) implementation in C

https://github.com/json-c/json-c/wiki

JSON (RFC 4627) interface for Glib

http://live.gnome.org/JsonGlib

JSON reader and writer library for C++

https://github.com/open-source-parsers/jsoncpp

Library to communicate using the JSON-RPC 2.0 specification

https://gitlab.gnome.org/GNOME/jsonrpc-glib

General purpose dynamic array

http://judy.sourceforge.net/

Humanist sans-serif font

https://www.theleagueofmoveabletype.com/junction

Unicode/MUFI OpenType font for medievalists (Latin, IPA, Runic, Greek)

http://junicode.sourceforge.net/

Regression testing utility for use with the Java(TM) Language

http://www.junit.org/

The editor which sucks less

http://www.mirbsd.org/jupp.htm

Japanized Vim-3.0

https://hp.vector.co.jp/authors/VA003457/vim/

Kubernetes command-line tool

https://github.com/derailed/k9s

Makefile framework

http://svn.netlabs.org/kbuild

System to administer web accounts for the KDE desktop

https://projects.kde.org/projects/kdereview/kaccounts-integration

Kanji-Kana Simple Inverter, language filter for Japanese

http://kakasi.namazu.org/

Digital camera manager for KDE

https://www.kde.org

Letter order game for KDE

https://www.kde.org/applications/education/kanagram

Japanese kana (Hiragana and Katakana) simple flashcard tool

https://kanatest.sourceforge.io/

Pac-Man Clone

https://www.kde.org/applications/games/kapman/

Free Unicode font for Sinhala script

http://www.kaputa.com/slword/kaputaunicode.htm

Dictionary management tool for anthy

http://kasumi.sourceforge.jp/

Dictionary management tool for anthy-unicode

https://github.com/fujiwarat/kasumi-unicode/

Sokoban-like Logic game

https://www.kde.org/applications/games/katomic/

Displays large Japanese letters on the standard output

http://kanji.zinbun.kyoto-u.ac.jp/~yasuoka/program.html

Blackbox Logic game

https://www.kde.org/applications/games/kblackbox

Falling Blocks game

https://www.kde.org/applications/games/kblocks/

Ball Bouncing game

https://www.kde.org/applications/games/kbounce/

Breakout-like game

https://www.kde.org/applications/games/kbreakout/