Since release 3.0, CGAL is available under an Open Source license as well as a commercial license. Users choosing to use CGAL under the free-of-charge Open Source license have to comply to its terms, otherwise they have to buy a commercial license.
Releases 3.x were distributed under the Q Public License (QPL) and GNU Lesser General Public License, v2.1 (LGPL). Starting from release 4.0, CGAL is available under the GNU General Public License (GPL) and the LGPL v3+. These license changes are not fundamental as the licenses are similar in their spirit. These changes only reflected the fact that the QPL had become marginal, since it had been introduced by The Qt Company (formally known as Trolltech) for their free version of Qt and was later abandoned.
We informally describe below our license scheme and the rights we give to our users. Do not hesitate to contact us if you have any question regarding the licenses.
Some parts of CGAL are available under the LGPL, whereas other parts are under the GPL. These two licenses introduce different constraints.
The idea is that the fundamental building blocks of CGAL are under the LGPL because this is a less constraining license which allows more people to build on top of this code without much constraints. This helps making the CGAL design a de-facto standard for geometric code which helps interoperability. The higher-level algorithms are typically released under the GPL in order to protect their commercial value. This makes it possible for us to exploit it commercially, which guarantees long term support, maintenance and further developments of the code for the benefit of the project and its users.
The Package Overview web page gives the license of each package. Approximately, the Kernel and Support libraries are under the LGPL, and most geometric algorithms and data structures are under the GPL, but there are some exceptions in both directions.
For the exact and formal details of the license, please always refer to the LICENSE file from the CGAL source code distribution.
The Lesser General Public License (v3+) gives you the right to use and copy the code freely. It is also possible to modify the code under the condition that the resulting modification is released as source code under the LGPL with any binary distribution of your software that uses these LGPL parts.
The GPL (v3+) is an Open Source license that, gives you the right to use, copy and modify the code freely. If you distribute your software based on GPLed CGAL data structures, you are obliged to distribute the modifications of CGAL you made, and you are furthermore obliged to distribute the source code of your own software under the GPL.
In cases where the constraints of the Open Source license prevent you from using CGAL, you can buy a commercial license for CGAL or parts of CGAL from GeometryFactory. The commercial offer is adapted to academic/research and industry customers.