# Licensing

Scipy is distributed under the modified (3-clause) BSD license. All code, documentation and other files added to Scipy by contributors is licensed under this license, unless another license is explicitly specified in the source code. Contributors keep the copyright for code they wrote and submit for inclusion to Scipy.

Other licenses that are compatible with the modified BSD license that Scipy uses are 2-clause BSD, MIT and PSF. Incompatible licenses are GPL, Apache and custom licenses that require attribution/citation or prohibit use for commercial purposes.

It regularly happens that PRs are submitted with content copied or derived from unlicensed code. Such contributions cannot be accepted for inclusion in Scipy. What is needed in such cases is to contact the original author and ask him to relicense his code under the modified BSD (or a compatible) license. If the original author agrees to this, add a comment saying so to the source files and forward the relevant email to the scipy-dev mailing list.

What also regularly happens is that code is translated or derived from code in R, Octave (both GPL-licensed) or a commercial application. Such code also cannot be included in Scipy. Simply implementing functionality with the same API as found in R/Octave/... is fine though, as long as the author doesn’t look at the original incompatibly-licensed source code.