In the ever-evolving landscape of open source licensing, developers often encounter a diverse range of licenses. One such license is CECILL-B, a unique open-source license that has gained popularity in France. In this article, we will provide an in-depth and detailed explanation of the CECILL-B license, its origins, key provisions, and implications for developers and users.

  1. Origins of CECILL-B:

CECILL-B, also known as “CEA CNRS INRIA Logiciel Libre,” is a license developed jointly by three major French research institutions: Commissariat à l’énergie atomique et aux énergies alternatives (CEA), Centre national de la recherche scientifique (CNRS), and Institut National de Recherche en Informatique et en Automatique (INRIA). Its primary goal is to foster the growth of open-source software within the French academic and research community.

  1. Copyleft Nature:

CECILL-B is a copyleft license, meaning it is a modified version of the GNU General Public License (GPL). The copyleft nature ensures that any modifications or derivative works based on the original software must also be made available under the same CECILL-B license. This provision ensures that the software and its modifications remain open source and freely accessible to the community.

  1. Granting Freedom and Rights:

Similar to other copyleft licenses, CECILL-B provides users with significant freedom to use, modify, and distribute the software. Users can freely access the source code, making it easier to study, modify, and improve the software based on their specific needs.

  1. Distribution Requirements:

Under CECILL-B, if users distribute a modified version of the software, they are required to make the source code of the modifications available to recipients. This transparency promotes collaboration, sharing of improvements, and encourages developers to contribute back to the open-source community.

  1. Compatibility with GPL:

CECILL-B is designed to be compatible with the GNU GPL, which means that software licensed under the CECILL-B license can be combined with software licensed under the GPL. This compatibility ensures a harmonious integration of CECILL-B-licensed software into the broader open-source ecosystem.

  1. French Legal System:

A notable aspect of CECILL-B is that it is drafted according to French law and is specifically tailored to comply with French legal requirements. This legal framework makes it an attractive choice for projects within the French academic and research communities.

  1. French Research Projects and Institutions:

CECILL-B is widely used in French research projects and institutions due to its alignment with the values and principles of academia. It fosters knowledge sharing, academic collaboration, and the promotion of open-source software within the research community.


In conclusion, CECILL-B, also known as CEA CNRS INRIA Logiciel Libre, is a copyleft open-source license developed collaboratively by major French research institutions. It grants users significant freedom to use, modify, and distribute software while requiring any modifications to be made available under the same license. CECILL-B’s compatibility with the GNU GPL and its compliance with French legal requirements make it an attractive choice for projects within the French academic and research communities. As open source continues to thrive, licenses like CECILL-B play a vital role in promoting collaboration, innovation, and the advancement of technology within the academic and research spheres.

If you’re interested in exploring a comprehensive list of various open-source licenses and their details, feel free to check out our guide to “Open Source Licenses : A Guide To Software Licensing“. Happy licensing!

CECILL-B References:

  1. CECILL-B License: Version 1.1, CEA CNRS INRIA Logiciel Libre
  2. GNU General Public License (GPL), Free Software Foundation
  3. Open Source Initiative

Note: The information provided in this article is for informational purposes only and should not be considered legal advice. Developers and users should consult legal experts for specific questions related to open-source licensing and compliance.

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