- Maxima (http://maxima.sourceforge.net) is a quite powerful computer
algebra system that can be told to output the results in Presentation
and Content MathML.
- wxMaxima (https://github.com/andrejv/wxmaxima/) is a feature-rich
graphical frontend for maxima that provides its own "Copy as MathML"
feature (Presentation only).
Both Programs are Open-Source (GPL).
Seems like one has to be a member of an organization in order to get
write access at the Wiki so I cannot add these programs myself.