Mathics is described as 'General purpose computer algebra system (CAS) and designed to be a free, light-weight alternative to Mathematica. It's programmable using a Mathematica like language and uses a web interface for user interaction' and is an app in the education & reference category. There are more than 10 alternatives to Mathics for a variety of platforms, including Windows, Linux, Web-based, Mac and iPhone apps. The best Mathics alternative is SageMath, which is both free and Open Source. Other great apps like Mathics are Mathematica, Calcpad, PTC Mathcad and Wolfram Language.