• Creative Commons Zero 1.0 UniversalCC0-1.0PermissiveCreative Commons2009Creative Commons — 2009 — A public-domain dedication instrument widely used for code snippets, data, test fixtures and reference material.
• Eclipse Public License 1.0EPL-1.0Weak copyleftEclipse Foundation2004Eclipse Foundation — 2004 — The earlier Eclipse weak-copyleft license, historically important in Java tooling and enterprise software.
• Eclipse Public License 2.0EPL-2.0Weak copyleftEclipse Foundation2017Eclipse Foundation — 2017 — Weak copyleft used across the Eclipse ecosystem, designed around modularity and commercial compatibility.
• European Union Public License 1.2EUPL-1.2Weak copyleftEuropean Commission2017European Commission — 2017 — European public-sector weak copyleft license with explicit compatibility language for multiple other licenses.
• 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.
• GNU Lesser General Public License v2.1LGPL-2.1-or-laterWeak copyleftFree Software Foundation1999Free Software Foundation — 1999 — The classic weak-copyleft library license of the pre-v3 GNU era, still common across infrastructure software.
• GNU Lesser General Public License v3.0LGPL-3.0-or-laterWeak copyleftFree Software Foundation2007Free Software Foundation — 2007 — Weak copyleft for libraries: the library itself stays free, but proprietary programs may link against it.
• GNU Lesser General Public License v3.0 onlyLGPL-3.0-onlyWeak copyleftFree Software Foundation2007Free Software Foundation — 2007 — LGPLv3 without the “or later” clause, preserving the exact GNU weak-copyleft text of version 3 only.
• GNU Library General Public License v2.0LGPL-2.0-or-laterWeak copyleftFree Software Foundation1991Free Software Foundation — 1991 — The older “Library GPL” predecessor to LGPL 2.1, historically significant in early free software libraries.
• ISC LicenseISCPermissiveInternet Systems Consortium1990sInternet Systems Consortium — 1990s — A concise permissive license often described as functionally similar to simplified BSD and MIT forms.
• MIT LicenseMITPermissiveMassachusetts Institute of Technology (historical form)1980sMassachusetts Institute of Technology (historical form) — 1980s — The most common short permissive license: minimal obligations, broad reuse rights, and near-universal tooling support.
• Mozilla Public License 1.1MPL-1.1Weak copyleftMozilla Foundation1999Mozilla Foundation — 1999 — The older Mozilla file-level weak copyleft, historically important before the simplification and compatibility work of MPL 2.0.
• Mozilla Public License 2.0MPL-2.0Weak copyleftMozilla Foundation2012Mozilla Foundation — 2012 — File-level copyleft used by Firefox and Thunderbird — a middle ground between GPL and permissive licenses.