Currently there are two distinct software implementations of CAD-score.
The original implementation is available from https://bitbucket.org/kliment/cadscore/downloads/".
The new CAD-score implementation is the "voronota-cadscore" script in the Voronota package that is available from https://bitbucket.org/kliment/voronota/downloads/.
The web server is running the original implementation.
In the older implementation, contacts are constructed for every atom by subdividing the expanded atom sphere according to the Voronoi neighbors. In the more recent implementation, contacts are derived directly from the Voronoi faces. The scores produced by implementations differ, but correlate very strongly. Note that the new implementation can run in the classic mode with the "--old-regime" flag.