This is a list of notablesoftwareforks.

• The many varieties ofproprietaryUnix in the 1980s and 1990s — almost all derived fromAT&T Unix under licence and all called "Unix", but increasingly mutually incompatible.SeeUNIX wars.
• MostLinux distributions are descended from other distributions, most being traceable back toDebian,Red Hat orSoftlanding 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 orMandriva) are rare.
• Pretty Good Privacy, forked outside of the United States to free it from restrictive US laws on theexportation of cryptographic software.
• The gameNetHack has spawned a number of variants using the original code, notablySlash'EM (1997), and was itself a fork (1987) ofHack.
• Openswan andstrongSwan, from the discontinuedFreeS/WAN.

• Symbolics Lisp Machine operating system, later called SymbolicsGenera. Forked from theMITLisp Machine operating system, which was licensed by MIT to Symbolics in 1980.^[1] This fork later motivatedRichard Stallman to start theGNU Project.^[2]

• POSTGRES (laterPostgreSQL), afterIngres branched off as a proprietary project.

• Microsoft SQL Server, fromSybase SQL Server, via a technology-sharing agreement concerning theTabular Data Stream protocol.
• SWLPC, fromLPMud.

• Xemacs, from GNUEmacs, originally for Lucid Corporation internal needs.

• FreeBSD, started as a patchkit to386BSD.
• NetBSD, started as a patchkit to386BSD.

• Apache HTTP Server, from the moribundNCSA HTTPd.
• OpenBSD, a fork ofNetBSD 1.0 byTheo de Raadt due to internal developer personality clashes.

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

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

• FilmGIMP, later calledCinePaint, fromGIMP, to handle 48-bit colour.
• OSSH fromSSH, when that project was proprietised.^[3]
• OpenSSH, fromOSSH.^[3]
• Sodipodi, from Gill.
• Steel Bank Common Lisp, fromCMU Common Lisp.

• TrueCrypt, fromE4M 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, fromStarOffice afterSun Microsystems made the source code publicly available. OpenOffice.org was eventually forked intoLibreOffice.

• ELinks, began as an experimental fork ofLinks.
• Fluxbox, fromBlackbox.
• GNU Radio, from pSpectra.
• Xvid, was a fork of OpenDivX.
• WebKit, project was started withinApple by Lisa Melton on 25 June 2001 as a fork ofKHTML.

• GForge, fromSourceForge.
• GraphicsMagick, fromImageMagick due to concerns over the openness of development.
• TheMatroska container format, from theMultimedia Container Format, due to differences in direction.
• MirOS BSD, fromOpenBSD.
• Syllable Desktop, from the stagnantAtheOS.

• aMule, fromxMule, which itself forked fromlMule shortly before, over developer disagreements.
• b2evolution, from b2/CafeLog.
• DragonFly BSD, fromFreeBSD 4.8 by long-time FreeBSD developerMatt Dillon, due to disagreement over FreeBSD 5's technical direction.
• Epiphany, fromGaleon, after developer disagreements about Galeon's growing complexity.
• Inkscape (vector-graphics program), fromSodipodi.
• NeoOffice, a fork ofOpenOffice.org, with an incompatible license (GPL rather than LGPL), due to disagreements about licensing and about the best method toport OpenOffice.org toMac OS X.
• TheSafari renderer that becameWebKit, fromKHTML.
• sK1, fromSkencil when the latter moved fromTk toGTK+.
• WordPress, from b2/CafeLog.
• Zen Cart, fromosCommerce.

• Baz, the previous version ofBazaar, fromGNU arch.
• FrostWire, fromLimeWire after LimeWire's developers considered adding RIAA-sponsored blocking code.
• MediaPortal, fromXBMC.
• WineX (later Cedega), was a proprietary fork ofWine.
• XOrg, fromXFree86, 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.

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

• Adempiere, a community maintained fork ofCompiere 2.5.3b, due to disagreement with commercial and technical direction of Compiere Inc.
• Cdrkit, fromCdrtools due to perceived licensing issues.^[4][5][6]
• LedgerSMB, fromSQL-Ledger, due to disagreements over handling of security issues.
• MindTouch, a fork ofMediaWiki.
• Mulgara, from Kowari after trademark threats fromNorthrop Grumman.
• MPC-HC,^[7] a fork ofMedia Player Classic.

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

• Boxee, a proprietary fork ofXBMC.
• Dreamwidth, fromLiveJournal by ex-LiveJournal developers.
• Drizzle, was intended as a slimmed-down and faster fork ofMySQL.
• MiaCMS, fromMambo.
• Plex, a proprietary fork ofXBMC.

• dbndns, fromdjbdns after the latter was released into the public domain and abandoned.
• Freeplane, fromFreeMind.
• FusionForge, fromGForge when GForge shifted focus to its proprietary version.
• Icinga, fromNagios, due to perceived slow development and problems dealing with Nagios LLC.^[8]
• kompoZer, fromNvu after that project went dormant.
• MariaDB, fromMySQL, over concern as toSun Microsystems' plans for the latter.
• Pale Moon, fromFirefox.
• Qt Extended Improved, fromQtopia after the latter was discontinued byQt Software.
• Voddler, is a proprietary fork ofXBMC andFFmpeg.

• Peppermint Linux OS, fromLubuntu, due to a perceived need for acloud-centric derivative of theUbuntuOS.
• Chamilo, fromDokeos, due to community management concerns with that project.
• LibreOffice, fromOpenOffice.org (and mergingGo-oo), due toOracle Corporation's perceived neglect of the software.
• OpenIndiana, fromOpenSolaris afterOracle Corporation discontinued the latter.
  • Illumos, from the OpenSolaris kernel OS/Net, after Oracle closed down public access to the source code.
• webtrees, fromPhpGedView, due toSourceForge's policy on exporting encryption.
• Xonotic, fromNexuiz, after that project was taken proprietary.
• Mageia, fromMandriva 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, fromOpenSSO afterOracle Corporation discontinued the latter.
• Calligra, fromKOffice after developer disagreements.

• Fire OS, a fork ofAndroid for theKindle Fire
• Jenkins, fromHudson (2011), due toOracle Corporation's perceived neglect of the project's infrastructure and disagreements over use of the name on non-Oracle-maintained infrastructure.
• Univa Grid Engine, fromOracle Grid Engine, afterOracle Corporation stopped releasing project source.
• Mer, started as a fork ofMeeGo.
• libav, a fork offfmpeg.
• WooCommerce, a fork of Jigoshop.^[9]

• MPC-BE, a fork ofMedia Player Classic

• Blink, a fork ofWebKit.
• SuiteCRM, from the last open source version ofSugarCRM.

• LibreSSL, fromOpenSSL.
• Nokia X software platform, a fork of theAndroid Open Source Project developed byNokia exclusively for itsX family of Android smartphones.
• io.js fromnode.js. In 2015 it was blessed as the official version of node.js.

• EdgeHTML, fromTrident
• Open Live Writer, fromWindows Live Writer 2012

• Collabora Online, fromLibreOffice, Collabora Online is a web-based enterprise ready edition of LibreOffice
• Goanna, fromGecko
• Nextcloud, fromownCloud
• LineageOS, fromCyanogenMod

• Bitcoin Cash, fromBitcoin Core, supported by the forked implementationsBitcoin ABC,Bitcoin Unlimited andBitcoin XT.
• Unified XUL Platform, fromXUL.^[10][11]

• Basilisk, fromFirefox.

• Trino, fromPresto.^[12]

• BuzzlyArt, fromArtrise
• Floorp, a free and open-source web browser based onFirefox.

• Angie, fromNginx.^[13]

• OpenTofu, fromTerraform.^[14]

• Freenginx, fromNginx.
• Valkey, fromRedis^[15]