The EGAD Library is a modular, object oriented approach to rational protein design. It is platform-independent, written in C++ and, most importantly, free. Its raison d'etre is to serve as a tool for building protein design applications. It can also be used as a test-bed for the comparison of different energy functions and minimization algorithms under the same physical model.
EGAD Library is based on the original C implementation of EGAD, by Navin Pokala. This is also available, though not supported by the EGAD Library developers.
Discussion about development, usage, feature requests, and anything relating to EGAD Library can be found on the egad_lib mailing list.
Citations of EGAD Library should reference our paper in the Journal of Computational Chemistry. (Reference is currently pending publication, information should hopefully be available by April)