MAXIMA 
Maxima is an open-source system for the manipulation of symbolic and numerical expressions, including:
- Differentiation
- Integration
- Taylor series
MAXIMA
DWSim
DWSIM is an open-source, steady-state chemical process simulator written in VB.NET. It has a HYSYS-like interface with many of the features present in commercial simulators:
- Thermodynamic models: Peng-Robinson, Soave-Redlich-Kwong, Lee-Kesler, UNIFAC, Ideal Gas;
