The CS-NPSA (Continuum Solvation Nonpolar Surface Area) package is a general purpose program suite for defining and computing non polar surface area based on continuum solvation models. 

It is based on the classification of individual surface elements representing the solvent accessible surface used for the description of the polarized charge density elements in the CS models. 

Currently, this program is interfaced with the quantum chemical program Turbomole and Orca. It can be used to calculate and visualize the non polar surface area.