TortoiseHg
TortoiseHg is a GUI front-end for Mercurial that runs on Microsoft Windows, Mac OS X, and Linux.
It is written in PyQt, and the underlying client can be used on the command line.
It is often recommended and preferred for working with Mercurial on Windows.
This is a brief list of its features:
It is free software released under the GNU General Public License.
TortoiseHg can be used as a client to a git server.
In June 2020, TortoiseHg moved off of bitbucket when they stopped hosting mercurial projects, and found a new home with heptapod.