Open Source Licenses : A Guide To Software Licensing

Open source licenses play a crucial role in the software development world. In this in-depth article, we delve into various open-source licenses and their implications for developers and users.

1. 0BSD – BSD Zero-Clause License:
   The 0BSD license, also known as the “Free Public License,” is incredibly permissive. It grants users complete freedom to modify, distribute, and use the software without imposing any conditions or restrictions. Users can freely incorporate the software into their projects, even without attributing the original author. This license is highly developer-friendly, promoting collaboration and sharing within the open-source community.
2. AAL – Attribution Assurance License:
   The Attribution Assurance License (AAL) is designed to strike a balance between open-source principles and proprietary licensing. It requires users to provide attribution to the original author when using the software. However, the AAL allows users to distribute the software under different licenses, making it versatile and flexible for various projects.
3. AGPL-3.0 – GNU Affero General Public License 3.0:
   The AGPL-3.0 is an extension of the GNU General Public License (GPL) that addresses specific concerns related to web applications. It ensures that users who interact with the software over a network have access to the corresponding source code. This “copyleft” provision ensures that users can freely examine, modify, and share the code used in web-based applications, thus maintaining the spirit of the open-source movement.
4. Apache-2.0 – Apache License, Version 2.0:
   The Apache-2.0 license is a permissive license that allows users to freely use, modify, and distribute the software. Unlike some other open-source licenses, Apache-2.0 includes a patent grant, ensuring that contributors grant recipients a license to use any patents owned by the contributor that are necessary to use or distribute the software. This provision adds an extra layer of protection for both developers and users.
5. APSL-2.0 – Apple Public Source License, Version 2.0:
   The APSL-2.0 is a license developed by Apple, combining open-source principles with provisions protecting Apple’s interests. While it grants users the freedom to use and modify the software, it contains clauses that require any modifications made to the source code to be made publicly available. This aims to foster transparency and collaboration within the Apple ecosystem.
6. Artistic-2.0 – Artistic License Version 2.0:
   The Artistic-2.0 license is unique and balances software freedom with certain distribution and licensing requirements. It allows users to freely use, modify, and distribute the software. However, it requires that modified versions of the software be given a different name, preventing confusion with the original work. This approach encourages creativity and innovation while ensuring clear differentiation between original and modified codebases.
7. Beerware – Beerware License:
   The Beerware license is a humorous and extremely permissive license that appeals to the open-source community’s light-hearted spirit. It simply requests users to buy the developer a beer if they find the software useful. It highlights the community’s friendly and collaborative nature and encourages users to acknowledge and appreciate the efforts of developers.
8. BSD-2-Clause – BSD 2-Clause “Simplified”:
   The BSD-2-Clause license is a simple and permissive license that allows users to freely use, modify, and redistribute the software. It requires users to include the original copyright notice in any distribution of the software. Additionally, it disclaims any warranty, limiting the liability of the original authors.
9. BSD-3-Clause – BSD 3-Clause “New” or “Revised”:
   The BSD-3-Clause license builds upon the BSD-2-Clause license by adding an additional clause to cover the use of names, trademarks, and endorsements. This license grants users significant freedom to use, modify, and distribute the software while ensuring proper attribution and preserving the original author’s endorsement rights.
10. CC-BY-SA-3.0 & CC-BY-SA-4.0 – Creative Commons Attribution-ShareAlike:
    The Creative Commons Attribution-ShareAlike licenses are commonly used for creative works, including software and documentation. These licenses permit users to share, adapt, and redistribute the software while requiring proper attribution to the original author. Additionally, if users create derivative works based on the software, they must distribute those works under the same license, promoting openness and collaboration.
11. CC0-1.0 – Public Domain/Creative Commons Zero 1.0:
    The CC0-1.0 license is a unique license that effectively places the work in the public domain, waiving all rights. It allows users to freely use, modify, and distribute the software without any restrictions, giving them maximum freedom and flexibility.
12. CDDL-1.0 – Common Development and Distribution License:
    The CDDL-1.0 is a copyleft license used mainly for software developed by Sun Microsystems (now owned by Oracle). It allows users to freely use, modify, and distribute the software, provided that any modifications or derivative works are made publicly available under the CDDL as well.
13. CECILL-B – CEA CNRS INRIA Logiciel Libre:
    The CECILL-B license is a French license compatible with the GPL. It emphasizes public accessibility and the protection of software freedom. This license aims to foster collaboration and knowledge sharing, particularly in academic and research environments.
14. CPAL-1.0 – Common Public Attribution License Version 1.0:
    The CPAL-1.0 is an attribution-based license that allows users to use, modify, and distribute the software. However, it requires that any changes made to the software are publicly available, promoting transparency and collaboration within the community.
15. ECL-2.0 – Educational Community License, Version 2.0:
    The ECL-2.0 is a permissive license designed for use in educational environments. It allows users to freely use, modify, and distribute the software, provided they comply with the license’s terms. The ECL-2.0 encourages educational institutions to share knowledge and collaborate on software projects.
16. EPL-1.0 & EPL-2.0 – Eclipse Public License:
    The Eclipse Public License is used primarily for software developed for the Eclipse IDE. It provides a strong copyleft for Eclipse projects, ensuring that any derived works must be distributed under the same license. It promotes the sharing of source code within the Eclipse community.

17. EUPL-1.2 – European Union Public License 1.2:
    The EUPL-1.2 is designed to ensure cross-border compatibility for European projects. It allows users to freely use, modify, and distribute the software across the European Union while providing proper attribution to the original authors.
18. GPL-1.0, GPL-2.0, & GPL-3.0 – GNU General Public License:
    The GNU General Public License (GPL) is one of the most well-known copyleft licenses. It requires that any derivative works or modifications to the software must be made publicly available under the same license. This ensures that the software remains open source and freely accessible to the community.
19. IPL-1.0 – IBM Public License:
    The IBM Public License is a permissive license used primarily for IBM’s open-source projects. It allows users to freely use, modify, and distribute the software, provided they comply with the license’s terms. The IPL-1.0 balances open-source principles with IBM’s interests.
20. ISC – Internet Systems Consortium License:
    The ISC license is a simple and permissive license widely used for open-source projects. It allows users to freely use, modify, and distribute the software while disclaiming any warranty. The ISC license is popular due to its simplicity and clarity.
21. LIL-1.0 – The Lil License v1:
    The Lil License v1 is an unrestrictive and humorous license, granting users complete freedom to modify and use the software. It embraces the playful and friendly nature of the open-source community.
22. LGPL-2.1 & LGPL-3.0 – Lesser General Public License:
    The Lesser General Public License (LGPL) is similar to the GPL but applies to libraries rather than complete applications. The LGPL allows dynamic linking with non-LGPL applications, providing more flexibility for developers and promoting code reuse.
23. MIT – MIT License:
    The MIT License is a simple and permissive license that allows users to freely use, modify, and distribute the software. It is one of the most popular open-source licenses due to its simplicity and lack of restrictions.
24. MPL-1.1 & MPL-2.0 – Mozilla Public License:
    The Mozilla Public License provides a strong copyleft for Mozilla projects. It allows users to freely use, modify, and distribute the software, provided they distribute any derivative works under the same license. The MPL fosters collaboration within the Mozilla community.
25. OSL-3.0 – Open Software License 3.0:
    The Open Software License (OSL) is a strong copyleft license that requires users to distribute any derivative works under the same license. It ensures that the software remains open source and freely accessible to the community.
26. Sendmail – Sendmail License:
    The Sendmail License is a permissive license used for the popular email transfer agent Sendmail. It allows users to freely use, modify, and distribute the software while disclaiming any warranty.
27. Ruby – Ruby License:
    The Ruby License is a permissive license used for the Ruby programming language. It allows users to freely use, modify, and distribute the software while disclaiming any warranty.
28. Unlicense – The Unlicense:
    The Unlicense is a unique license that effectively places the work in the public domain, waiving all rights. It allows users to freely use, modify, and distribute the software without any restrictions, giving them maximum freedom and flexibility.
29. WTFPL – Do What the Fuck You Want to Public License:
    The WTFPL is a humorous and extremely permissive license that allows users to do whatever they want with the software. It reflects the playful and irreverent spirit of the open-source community.
30. Zlib – Zlib/libpng License:
    The Zlib license is a permissive license used for the Zlib and libpng libraries. It allows users to freely use, modify, and distribute the software with very few restrictions.
31. ZPL-2.0 – Zope Public License 2.0:
    The Zope Public License is a strong copyleft license used primarily for software related to the Zope application server. It requires that any modifications or derivative works be distributed under the same license. This ensures that the software remains open source and freely accessible to the community.

Understanding these licenses empowers developers to choose the right license for their projects while fostering collaboration and innovation within the open-source community. Each license carries unique provisions, and selecting the appropriate license is essential to ensure the intended use and distribution of the software align with the developer’s goals. Additionally, users must comply with the terms of the license to avoid potential legal issues and maintain the spirit of open-source software development. By exploring and comprehending the nuances of various open-source licenses, developers can make informed decisions that contribute to the continued growth and success of the open-source community.