Open source and free licences

Notes from Alexandre Sevin (

A license is a contract; it gives some rights but also some obligations. A license is a contract; it gives some rights but also some obligations. It is an adhesion contract (not negotiable).
Free is different from open source.
A license is free if:

  • the product can be freely studied
  • the product can be used and reproduced
  • the product can be modified
  • the product, modified or not, can be redistributed (at least under the same license)

A license is open source if:

  • you can redistribute the product
  • you have access to the source code
  • you can modify it
  • you can use it in your project
  • the license do not discriminate any people or uses
  • it is not specific to a product
  • it has no effect on other software
  • it is “technical neutral” (ie it does not discriminate any technology)

Example of other type of licences:

  • freeware: it is cost-free but not free
  • licences free for research use but not for commercial use

Three main categories of licence you can find in open source project:

  • GNU GPL like: if you use a piece of code under this license in your project, all your project have to be under the same license.
  • GNU LGPL like: a code under this type of licence have to remain under this type of licence, but the other parts of a project using this code can be under any type of licence.
  • BSD like: You can do what you want with the code under this licence.

INRIA created three licences following the same schema:

  • CeCILL for GNU GPL
  • CeCILL B for BSD

Be careful when you want to change the licence of your project

  • The changes are not retroactive: if you want to change an open source licence to a commercial one, the old version of your project will still be online and free to use.
  • You have to be careful with the code you are using in your project. Maybe that some pieces are under a very restrictive licence.
  • Who are the authors of the project? Every single author has to agree this change. (Interns keep their copyrights, unless there is a specific clause in their contracts. Most of the time, employees give their copyrights to their employer.)

Advices from the speaker:
-> Think on the scope of what you need-> Don’t think “I make my project open source to have a community behind it”. Creating a community is hard and needs a lot of work.

-> To make the change of strategy easier, track the IPs and the dependences of your project.

FOSsology can help you tracking the licences of the code you are using in your project.
In France, if you don’t put any licence on your project but you put it on Github, you only give the rights to read your code. In France, there is no jurisprudence for now. We do not know if the American licences are legal or not under the French law.

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