GraphPad Prism - Overview. GraphPad Prism, available for both Windows and Mac computers, combines scientific graphing, comprehensive curve fitting (nonlinear regression), understandable statistics, and data organization.
GeoGebra CAS Calculator - Free online algebra calculator from GeoGebra: solve equations, expand and factor expressions, find derivatives and integrals
OriginLab - OriginLab is a data analysis tool that provide the engineers and scientist with the technical charts and system for 2D and 3D plotting and all kind of fitting including curve and peak fitting.
Giac/Xcas - Free computer algebra system
SciDaVis - SciDAVis is a free application for Scientific Data Analysis and Visualization.
GnuPlot - Gnuplot is a portable command-line driven interactive data and function plotting utility.