libdEdx provide libraries to calculate stopping power offline.
libdedx is written in C, and provides access to a variety of stopping power data, CSDA range calculations, inverse stopping power lookups, and requested energy for a given CSDA range. The library is available on sourceforge, and it is licensed under GNU GPL.
At the moment the library is only available for Linux users. If there is interest for a Windows version it will be provided on demand.
Along with the library a simple command line program is shipped getdedx, which allows you to calculate stopping power directly.