Undated

• The many varieties of proprietary Unix in the 1980s and 1990s — almost all derived from AT&T Unix under licence and all called "Unix", but increasingly mutually incompatible. See UNIX wars.
• Most Linux distributions are descended from other distributions, most being traceable back to Debian, Red Hat or Softlanding Linux System (see image right). Since most of the content of a distribution is free and open source software, ideas and software interchange freely as is useful to the individual distribution. Merges (e.g., United Linux or Mandriva) are rare.
• Pretty Good Privacy, forked outside of the United States to free it from restrictive US laws on the exportation of cryptographic software.
• The game NetHack has spawned a number of variants using the original code, notably Slash'EM (1997), and was itself a fork (1987) of Hack.
• Openswan and strongSwan, from the discontinued FreeS/WAN.

1981

• Symbolics Lisp Machine operating system, later called Symbolics Genera. Forked from the MIT Lisp Machine operating system, which was licensed by MIT to Symbolics in 1980.¹ This fork later motivated Richard Stallman to start the GNU Project.²

1985

• POSTGRES (later PostgreSQL), after Ingres branched off as a proprietary project.

1990

• Microsoft SQL Server, from Sybase SQL Server, via a technology-sharing agreement concerning the Tabular Data Stream protocol.
• SWLPC, from LPMud.

1991

• Xemacs, from GNU Emacs, originally for Lucid Corporation internal needs.

1993

• FreeBSD, started as a patchkit to 386BSD.
• NetBSD, started as a patchkit to 386BSD.

1995

• Apache HTTP Server, from the moribund NCSA HTTPd.
• OpenBSD, a fork of NetBSD 1.0 by Theo de Raadt due to internal developer personality clashes.

1997

• EGCS was a fork of GCC, later named as the official version.

1998

• Grace, from Xmgr, after that project ceased development.

1999

• FilmGIMP, later called CinePaint, from GIMP, to handle 48-bit colour.
• OSSH from SSH, when that project was proprietised.³
• OpenSSH, from OSSH.⁴
• Sodipodi, from Gill.
• Steel Bank Common Lisp, from CMU Common Lisp.

2000

• TrueCrypt, from E4M when the latter was discontinued.
• Tux Racer went proprietary in 2000, leading to several forks including OpenRacer, PlanetPenguin Racer and Extreme Tux Racer.
• OpenOffice.org, from StarOffice after Sun Microsystems made the source code publicly available. OpenOffice.org was eventually forked into LibreOffice.

2001

• ELinks, began as an experimental fork of Links.
• Fluxbox, from Blackbox.
• GNU Radio, from pSpectra.
• Xvid, was a fork of OpenDivX.
• WebKit, project was started within Apple by Lisa Melton on 25 June 2001 as a fork of KHTML.

2002

• GForge, from SourceForge.
• GraphicsMagick, from ImageMagick due to concerns over the openness of development.
• The Matroska container format, from the Multimedia Container Format, due to differences in direction.
• MirOS BSD, from OpenBSD.
• Syllable Desktop, from the stagnant AtheOS.

2003

• aMule, from xMule, which itself forked from lMule shortly before, over developer disagreements.
• b2evolution, from b2/CafeLog.
• DragonFly BSD, from FreeBSD 4.8 by long-time FreeBSD developer Matt Dillon, due to disagreement over FreeBSD 5's technical direction.
• Epiphany, from Galeon, after developer disagreements about Galeon's growing complexity.
• Inkscape (vector-graphics program), from Sodipodi.
• NeoOffice, a fork of OpenOffice.org, with an incompatible license (GPL rather than LGPL), due to disagreements about licensing and about the best method to port OpenOffice.org to Mac OS X.
• The Safari renderer that became WebKit, from KHTML.
• sK1, from Skencil when the latter moved from Tk to GTK+.
• WordPress, from b2/CafeLog.
• Zen Cart, from osCommerce.

2004

• Baz, the previous version of Bazaar, from GNU arch.
• FrostWire, from LimeWire after LimeWire's developers considered adding RIAA-sponsored blocking code.
• MediaPortal, from XBMC.
• WineX (later Cedega), was a proprietary fork of Wine.
• XOrg, from XFree86, in order to adopt a more open development model and due to concerns over the latter's change to a license many distributors found unacceptable.

2005

• Audacious, from Beep Media Player to continue work on the old version of that project.
• Joomla, from Mambo due to concerns over project structure.
• Claws Mail, from Sylpheed, due to perceived slowness in accepting enhancements.

2006

• Adempiere, a community maintained fork of Compiere 2.5.3b, due to disagreement with commercial and technical direction of Compiere Inc.
• Cdrkit, from Cdrtools due to perceived licensing issues.⁵⁶⁷
• LedgerSMB, from SQL-Ledger, due to disagreements over handling of security issues.
• MindTouch, a fork of MediaWiki.
• Mulgara, from Kowari after trademark threats from Northrop Grumman.
• MPC-HC,⁸ a fork of Media Player Classic.

2007

• Go-oo, from OpenOffice.org, due to that project's contributor licensing agreement.

2008

• Boxee, a proprietary fork of XBMC.
• Dreamwidth, from LiveJournal by ex-LiveJournal developers.
• Drizzle, was intended as a slimmed-down and faster fork of MySQL.
• MiaCMS, from Mambo.
• Plex, a proprietary fork of XBMC.

2009

• dbndns, from djbdns after the latter was released into the public domain and abandoned.
• Freeplane, from FreeMind.
• FusionForge, from GForge when GForge shifted focus to its proprietary version.
• Icinga, from Nagios, due to perceived slow development and problems dealing with Nagios LLC.⁹
• kompoZer, from Nvu after that project went dormant.
• MariaDB, from MySQL, over concern as to Sun Microsystems' plans for the latter.
• Pale Moon, from Firefox.
• Qt Extended Improved, from Qtopia after the latter was discontinued by Qt Software.
• Voddler, is a proprietary fork of XBMC and FFmpeg.

2010

• Peppermint Linux OS, from Lubuntu, due to a perceived need for a cloud-centric derivative of the Ubuntu OS.
• Chamilo, from Dokeos, due to community management concerns with that project.
• LibreOffice, from OpenOffice.org (and merging Go-oo), due to Oracle Corporation's perceived neglect of the software.
• OpenIndiana, from OpenSolaris after Oracle Corporation discontinued the latter.
  • Illumos, from the OpenSolaris kernel OS/Net, after Oracle closed down public access to the source code.
• webtrees, from PhpGedView, due to SourceForge's policy on exporting encryption.
• Xonotic, from Nexuiz, after that project was taken proprietary.
• Mageia, from Mandriva Linux, due to financial uncertainty and the layoff by Edge-IT, a Mandriva subsidiary employing many of the corporate staff working on the Mandriva distribution
• OpenAM, from OpenSSO after Oracle Corporation discontinued the latter.
• Calligra, from KOffice after developer disagreements.

2011

• Fire OS, a fork of Android for the Kindle Fire
• Jenkins, from Hudson (2011), due to Oracle Corporation's perceived neglect of the project's infrastructure and disagreements over use of the name on non-Oracle-maintained infrastructure.
• Univa Grid Engine, from Oracle Grid Engine, after Oracle Corporation stopped releasing project source.
• Mer, started as a fork of MeeGo.
• libav, a fork of ffmpeg.
• WooCommerce, a fork of Jigoshop.¹⁰

2012

• MPC-BE, a fork of Media Player Classic

2013

• Blink, a fork of WebKit.
• SuiteCRM, from the last open source version of SugarCRM.

2014

• LibreSSL, from OpenSSL.
• Nokia X software platform, a fork of the Android Open Source Project developed by Nokia exclusively for its X family of Android smartphones.
• io.js from node.js. In 2015 it was blessed as the official version of node.js.

2015

• EdgeHTML, from Trident
• Open Live Writer, from Windows Live Writer 2012

2016

• Collabora Online, from LibreOffice, Collabora Online is a web-based enterprise ready edition of LibreOffice
• Goanna, from Gecko
• Nextcloud, from ownCloud
• LineageOS, from CyanogenMod

2017

• Bitcoin Cash, from Bitcoin Core, supported by the forked implementations Bitcoin ABC, Bitcoin Unlimited and Bitcoin XT.
• Unified XUL Platform, from XUL.¹¹¹²

2018

• Basilisk, from Firefox.

2019

• Trino, from Presto.¹³

2021

• BuzzlyArt, from Artrise
• Floorp, a free and open-source web browser based on Firefox.

2022

• Angie, from Nginx.¹⁴

2023

• OpenTofu, from Terraform.¹⁵

2024

• Freenginx, from Nginx.
• Valkey, from Redis¹⁶

References

1. MIT Lisp Machine License Signed Press Release October 1980 http://www.textfiles.com/bitsavers/pdf/symbolics/LM-2/MIT_Lisp_Machine_License_Signed_Press_Release_Oct1980.pdf ↩

2. Richard Stallman, My Lisp Experiences and the Development of GNU Emacs https://www.gnu.org/gnu/rms-lisp.html ↩

3. "OpenSSH Project History". OpenSSH. 2016-04-20. Retrieved 2016-08-03. http://www.openssh.com/history.html ↩

4. "OpenSSH Project History". OpenSSH. 2016-04-20. Retrieved 2016-08-03. http://www.openssh.com/history.html ↩

5. Corbet, Jonathan (2006-08-12). "cdrtools - a tale of two licenses". LWN.net. Retrieved 2016-08-03. https://lwn.net/Articles/195167/ ↩

6. Jaspert, Joerg (2006-09-04). "cdrkit (fork of cdrtools) uploaded to Debian, please test". debian-devel-announce. Debian. Retrieved 2016-08-03. https://lists.debian.org/debian-devel-announce/2006/09/msg00002.html ↩

7. "RM: cdrtools -- RoM: non-free, license problems". Debian. 2006-01-31. Retrieved 2016-08-03. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=377109 ↩

8. "Change log of release date from MPC-HC project". https://trac.mpc-hc.org/wiki/Changelog ↩

9. "Frequently Asked Questions". Icinga. Retrieved 2016-08-03. https://www.icinga.org/resources/faq/ ↩

10. "Jigoshop Rise and Fall - How Did It Come to End of Jigoshop eCommerce Plugin?". 27 April 2020. https://www.kasareviews.com/jigoshop-review-end-of-jigoshop-ecommerce/ ↩

11. "README for the initial, deprecated UXP repository on GitHub". GitHub. Retrieved 2018-04-25. https://github.com/MoonchildProductions/moebius/blob/master/README.md ↩

12. "REMADE for the current UXP repository on GitHub". GitHub. Retrieved 2018-04-25. https://github.com/MoonchildProductions/UXP/blob/v2018.04.23/README.md ↩

13. Phillips, David; Sundstrom, Dain; Traverso, Martin (27 December 2020). "We're rebranding PrestoSQL as Trino". trino.io. Retrieved 4 October 2022. https://trino.io/blog/2020/12/27/announcing-trino.html ↩

14. Darkcrizt (2022-11-03). "Angie, the Nginx fork created by developers who left F5". Desde Linux. Retrieved 2023-12-14. https://blog.desdelinux.net/en/angie-the-nginx-fork-created-by-devs-who-ditched-f5/ ↩

15. "Linux Foundation Launches OpenTofu: A New Open Source Alternative to Terraform". Linux Foundation. Linux Foundation. Retrieved 29 April 2024. https://www.linuxfoundation.org/press/announcing-opentofu ↩

16. "Linux Foundation Launches Open Source Valkey Community". Linux Foundation. 28 March 2024. Retrieved 29 April 2024. https://www.linuxfoundation.org/press/linux-foundation-launches-open-source-valkey-community ↩