ThePEG (Toolkit for High Energy Physics Event Generation) is a generic platform for building and using Monte Carlo event generators in the C++ programming language. Its purpose is to provide those software parts that are common to many different event generators.
Public versions can be viewed and downloaded here.
Users with a HepForge account can access all versions of the source code by using e.g.
hg clone ssh://email@example.com//hepforge/hg/thepeg/public/ThePEG
foo should be replaced by the HepForge username.