Mathics is a general-purpose computer algebra system (CAS). It is an open-source alternative to Mathematica. It is free both as in "free beer" and as in "freedom".
The home page of Mathics is http://mathics.github.io.
To install so that you run from the source tree:
$ make develop
More detailed information is available on the Mathics Wiki here.
Once Mathics is installed you can run the Django-based web front-end like this:
$ mathicsserver
For a crude GNU-Readline command-line interface that doesn't provide graphics run
$ mathics
To get more information on both commands add --help at the end of the command.
For an experiemental Jupyter-based consoles and web interfaces see iwolfram. (We this will drop the "experimental" by the next release.)
Alternatively to the installation step above, mathics can be installed and run via docker. Please refer to sealemar/mathics-dockerized repo for instructions.
Please feel encouraged to contribute to Mathics! Create your own fork, make the desired changes, commit, and make a pull request.
Mathics is released under the GNU General Public License Version 3 (GPL3).