Creative Commons Zero 1.0 UniversalA public-domain dedication instrument widely used for code snippets, data, test fixtures and reference material.Eclipse Public License 1.0The earlier Eclipse weak-copyleft license, historically important in Java tooling and enterprise software.Eclipse Public License 2.0Weak copyleft used across the Eclipse ecosystem, designed around modularity and commercial compatibility.European Union Public License 1.2European public-sector weak copyleft license with explicit compatibility language for multiple other licenses.GNU Affero General Public License v3.0Copyleft 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 onlyGNU AGPLv3 without the “or later” clause, extending source-sharing obligations to network users of the software.GNU Free Documentation License v1.3Copyleft for manuals and documentation, designed so free software ships with free documentation. Wikipedia's original license.GNU General Public License v1.0The original GNU copyleft license that established the basic reciprocity model later refined by GPLv2 and GPLv3.GNU General Public License v2.0The license of the Linux kernel and decades of free software history. A foundational copyleft text.GNU General Public License v2.0 onlyGPLv2 without the automatic “or later” clause. Important for kernel-space and projects that pin precisely to v2.GNU General Public License v3.0The strongest widely-used copyleft license. Derivative works must remain free under the same terms.GNU General Public License v3.0 onlyGPLv3 without the “or later” upgrade clause, preserving the stronger anti-tivoization and patent terms of version 3 only.GNU Lesser General Public License v2.1The classic weak-copyleft library license of the pre-v3 GNU era, still common across infrastructure software.GNU Lesser General Public License v3.0Weak copyleft for libraries: the library itself stays free, but proprietary programs may link against it.GNU Lesser General Public License v3.0 onlyLGPLv3 without the “or later” clause, preserving the exact GNU weak-copyleft text of version 3 only.GNU Library General Public License v2.0The older “Library GPL” predecessor to LGPL 2.1, historically significant in early free software libraries.ISC LicenseA concise permissive license often described as functionally similar to simplified BSD and MIT forms.MIT LicenseThe most common short permissive license: minimal obligations, broad reuse rights, and near-universal tooling support.Mozilla Public License 1.1The older Mozilla file-level weak copyleft, historically important before the simplification and compatibility work of MPL 2.0.Mozilla Public License 2.0File-level copyleft used by Firefox and Thunderbird — a middle ground between GPL and permissive licenses.