In addition to GCA (the official character design program), there's also
GURPS Character Sheet (GCS). It's in Java, and open source, if that's your thing.
Data entry for all the traits seems to me to be one of the biggest hurdles, at least measured by tedium per unit progress. One of my wish-list items for a 5e, should they ever do one, would be an official set of data files with a documented format that people could use for their own play aids.