GeoGebra CAS Calculator - Free online algebra calculator from GeoGebra: solve equations, expand and factor expressions, find derivatives and integrals
SMath Studio - Tiny, powerful, free mathematical program with WYSIWYG editor and complete units of measurements support.
Dr. Geo - Dr. Geo, a software to design & manipulate interactive geometric sketches.
Wolfram Mathematica - Mathematica has characterized the cutting edge in specialized processing—and gave the chief calculation environment to a large number of pioneers, instructors, understudies, and others around the globe.
Giac/Xcas - Free computer algebra system
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming