Singular is a computer algebra system for polynomial computations, with
special emphasis on commutative and non-commutative algebra, algebraic
geometry, and singularity theory. It is free and open-source under the
GNU General Public Licence.

Installation instructions from source code:
  https://github.com/Singular/Sources/wiki/Step-by-Step-Installation-Instructions-for-Singular

Homepage:
  http://www.singular.uni-kl.de/

Source code:
  https://github.com/Singular/Sources

User Manual:
  http://www.singular.uni-kl.de/Manual/latest