• Affero General Public License v1.0AGPL-1.0-onlyCopyleftAffero, Inc.2002Affero, Inc. — 2002 — The earlier network-focused Affero copyleft that inspired the GNU AGPL line.
• CeCILL 2.1CECILL-2.1CopyleftCEA / CNRS / INRIA2013CEA / CNRS / INRIA — 2013 — French free software copyleft license aligned with European law and intended to remain GPL-compatible.
• Creative Commons Attribution-ShareAlike 3.0CC-BY-SA-3.0CopyleftCreative Commons2007Creative Commons — 2007 — The previous ShareAlike generation, still carried by an enormous body of existing works — including years of Wikipedia history.
• Creative Commons Attribution-ShareAlike 4.0CC-BY-SA-4.0CopyleftCreative Commons2013Creative Commons — 2013 — Copyleft for cultural works: adaptations must be shared under the same terms. The license of Wikipedia and much of the free culture movement.
• GNU Affero General Public License v3.0AGPL-3.0-or-laterCopyleftFree Software Foundation2007Free Software Foundation — 2007 — Copyleft that also covers software used over a network — users of a service must be able to get its source.
• GNU Affero General Public License v3.0 onlyAGPL-3.0-onlyCopyleftFree Software Foundation2007Free Software Foundation — 2007 — GNU AGPLv3 without the “or later” clause, extending source-sharing obligations to network users of the software.
• GNU Free Documentation License v1.3GFDL-1.3-or-laterCopyleftFree Software Foundation2008Free Software Foundation — 2008 — Copyleft for manuals and documentation, designed so free software ships with free documentation. Wikipedia's original license.
• GNU General Public License v1.0GPL-1.0-or-laterCopyleftFree Software Foundation1989Free Software Foundation — 1989 — The original GNU copyleft license that established the basic reciprocity model later refined by GPLv2 and GPLv3.
• GNU General Public License v2.0GPL-2.0-or-laterCopyleftFree Software Foundation1991Free Software Foundation — 1991 — The license of the Linux kernel and decades of free software history. A foundational copyleft text.
• GNU General Public License v2.0 onlyGPL-2.0-onlyCopyleftFree Software Foundation1991Free Software Foundation — 1991 — GPLv2 without the automatic “or later” clause. Important for kernel-space and projects that pin precisely to v2.
• GNU General Public License v3.0GPL-3.0-or-laterCopyleftFree Software Foundation2007Free Software Foundation — 2007 — The strongest widely-used copyleft license. Derivative works must remain free under the same terms.
• GNU General Public License v3.0 onlyGPL-3.0-onlyCopyleftFree Software Foundation2007Free Software Foundation — 2007 — GPLv3 without the “or later” upgrade clause, preserving the stronger anti-tivoization and patent terms of version 3 only.
• Open Software License 3.0OSL-3.0CopyleftLawrence Rosen2005Lawrence Rosen — 2005 — A strong copyleft license with explicit patent language and conditions oriented toward modern software distribution.
• SIL Open Font License 1.1OFL-1.1CopyleftSIL International2005SIL International — 2005 — The standard free license for fonts: fonts may be used, modified and redistributed, but must stay under the OFL.