Graphical Git client designed to help you understand and manage your source code history
Features:
The best open source git client I've seen out there. Even though it took me a little to get used to the UI distribution, it has a lot of features and everything just works in an excellent manner. Unlike CrushingJosch, I had no problems linking my GitHub account, just be aware that if 2FA is enabled, you need to create an access token instead of using your password (the GittyUp UI tells you to do so and has a link to the GitHub docs showing how to create a token).
As someone being used to GitKraken, I really enjoy the detailed gui layout of GittyUp. I did not really succeed adding my github account to the software (that's why it's not 5 stars for me), but I can just open or clone repos and work on them anyways.