SCM Workbench is a GUI to easily work with Git, Mercurial (hg) and Subversion (svn) repositories in the style of PySVN WorkBench
Support for Perforce (p4) is in development.
Visit the main https://scm-workbench.barrys-emacs.org site for full details.
See Sources/Scm/README.txt for information on running SCM Workbench from source.