.... It features its own programming language, and many users have contributed useful packages in various areas over the decades. It is GPL-licensed and largely written in Common Lisp. Executables can be downloaded for Windows, Mac, Linux, and Android; source code is also available. An active community maintains and extends the system.
Website: https://maxima.sourceforge.io
Additional add-on packages for Maxima can be found at: https://github.com/maxima-project-on-github/maxima-packages