SciDaVis - SciDAVis is a free application for Scientific Data Analysis and Visualization.
GeoGebra CAS Calculator - Free online algebra calculator from GeoGebra: solve equations, expand and factor expressions, find derivatives and integrals
LabPlot - LabPlot is a KDE-application for interactive graphing and analysis of scientific data.
Dr. Geo - Dr. Geo, a software to design & manipulate interactive geometric sketches.
GnuPlot - Gnuplot is a portable command-line driven interactive data and function plotting utility.
Giac/Xcas - Free computer algebra system