A non-exhaustive list of explored as well as unexplored open-source software development tools and software applications. For an exhaustive list, take a look at Wikidata.
Application Development
- API
- wsgen
- Bug Reporting and Feature Requests
- Bugzilla
- Trac
- Cache Management
- Ehcache
- Memcached
- Compilation and pre-processing (C/C++)
- cc
- gcc
- g++
- Continuous Integration
- Jenkins
- Travis
- CircleCI
- Configuration of Application
- Ansible
- Chef
- Juju
- Puppet
- Salt
- Vagrant
- Data Formattng and Validation
- jsonlint
- xmllint
- Data Storage
- NoSQL
- Arangodb
- Cassandra
- Couchdb
- Elliptics
- Flockdb
- Hbase
- Hypertable
- Mapdb
- Mongodb
- Mongo
- Neo4j
- Opentsdb
- Orientdb
- Pouchdb
- Ravendb
- Redis
- Rethinkdb
- Riak
- Titan
- SQL
- Mariadb
- Mysql
- Postgresql
- Sqlite
- NoSQL
- Debugging
- gdb
- ltrace
- strace
- Dependency and Package Management
- npm
- pip
- snap
- flatpak
- Design of Applications
- Dia
- Umbrello
- Umlet
- Metrics
- ps
- netstat
- Libray linking
- ldconfig
- ldd
- ld
- ar
- nm
- ranlib
- Localization and Internationalization
- locale
- gettext
- gettextize
- Log
- Log4j
- Apache Commons Logging
- Profile
- gprof
- Queue
- Apache Kafka
- Apache ActiveMQ
- REPL
- python
- repl
- Realtime
- top
- Scheduling
- cron
- Search
- grep
- find
- locate
- Software Specification
- TLA+
- Threading
- pthread
- User Interface
- QML
- HTML
- Version Control
- CVS
- SVN
- Git
- Pijul
- Fossil
- Mercurial
- Bazaar
- Wiki
- Dokuwiki
- Mediawiki
- Phpwiki
- Twiki
- Xwiki
Operating Systems
- Anykernel
- Rump kernel
- Desktop Environment
- KDE
- GNOME
- XFCE
- LXDE
- Filesystem
- ext4
- Overlayfs
- Aufs
- Monolithic
- Coreos
- FirefoxOS
- Linux Distributions
- Archlinux
- CentOS
- Cinnamon
- Debian
- Fedora
- Linuxmint
- Opensuse
- Ubuntu
- FreeBSD
- NixOS
- Unikernels
- ClickOS
- Clive
- HaLVM
- Ling
- MirageOS
- OSv
Platform as a Service (PaaS)
- CloudFoundry
- OpenStack
Application Packaging
- Containers
- LXC
- Docker
- Distributions
- Ubuntu
- Fedora
- RedHat
- umake
Shell
- Bash
- Fish-shell
- Ksh
- Sh
- Zsh
Web Browser
- Chromium
- Firefox
Web development
- Haskell
- Happstack
- Snap
- Yesod
- Java
- Grails
- Play
- Javascript
- Angularjs
- Backbonejs
- Emberjs
- Expressjs
- Famous
- Meteor
- Nodejs
- Php
- Cakephp
- Laravel
- Phalcon
- Symphony
- Zend
- Python
- Django
- Flask
- Pyramid
- Ruby
- Rails
- Scala
- Play
Data Analysis
- Ipython
- Mondrian
- Olap4j
- Pandas
- Pentaho
Data Visualization
- D3
- Gephi
- Gnuplot
- Matplotlib
- Processing
Programming Languages
- C
- C++
- Clojure
- Coffeescript
- D
- Dart
- Delphi
- Eiffel
- Elixir
- Elm
- Erlang
- Euphoria
- F#
- Fortran
- Go
- Groovy
- Haskell
- Java
- Javascript
- Julia
- Lisp
- Livescript
- Lua
- Objectivec
- Ocaml
- Perl
- Php
- Prolog
- Purescript
- Python
- R
- Ruby
- Rust
- Sage
- Scala
- Scheme
- Shell
- Smalltalk
- Sql
- Wyvern
Markup Languages
- HTML
- JSON
- XML
- QML
Content Management Systems (CMS)
- Diaspora
- Drupal
- Ghost
- Joomla
- Mediagoblin
- Wordpress
Computing
- Maxima
- Octave
- R
Container Technologies
- Docker
- Libvirt-lxc
- Lxc
- Openvz
- Rocket
- Runc
Dictionary
- Artha
- Aspell
- Goldendict
Editor
- Aloha
- Atom
- Emacs
- Vim
Web Forum
- Bbpress
- Discourse
- Phpbb
- Vanilla
Gaming Development
- Steam
Computer Graphics
- 2d
- Inkscape
- 3d
- Blender
- Photography
- Gimp
- Publishing
- Krita
- Video
- pitivi
Machine Learning
- Mahout
- Moa
- Opencv
- Opennn
- Orange
- Spark
Markdown Editor
- Retext
Memory Mapping
- Anki
- Freeplane
Music
- Frescobaldi
- Lilypond
- Musescore
- Solfege
Natural Language Processing
- Nltk
Semantic Web
- Jena
- Protege
Web Server
- Apache
- Jetty
- Lighttpd
- Nginx
- Tomcat