Git comes with built-in GUI tools for committing (git-gui) and browsing (gitk), but there are several third-party tools for users looking for platform-specific experience.
If you want to add another GUI tool to this list, just follow the instructions.
SourceTree
Platforms: Mac, Windows Price: Free License: Proprietary
GitHub Desktop
Platforms: Mac, Windows Price: Free License: MIT
TortoiseGit
Platforms: Windows Price: Free License: GNU GPL
Git Extensions
Platforms: Linux, Mac, Windows Price: Free License: GNU GPL
Platforms: iOS Price: Free with in-app purchases License: Proprietary
GitX-dev
Platforms: Mac Price: Free License: GNU GPL
GitBlade
Platforms: Linux, Mac, Windows Price: Free Lite version, $59.99/user/year for PRO version License: Proprietary
Guitar
Platforms: Linux, Mac, Windows Price: Free License: GNU GPL
RepoZ
Platforms: Mac, Windows Price: Free License: MIT
Cong
Platforms: Windows Price: Free License: Proprietary
Sublime Merge
Platforms: Linux, Mac, Windows Price: $99/user, $75 annual business sub, free eval License: Proprietary
LazyGit
Platforms: Linux, Mac, Windows Price: Free License: MIT
SnailGit
Platforms: Mac Price: $9.99 / Lite version License: Proprietary
GitAtomic
Platforms: Windows Price: 15.00€ License: Proprietary
Gitfox
Platforms: Mac Price: €3.99/m or €24,99/y per user License: Proprietary
GitFiend
Platforms: Linux, Mac, Windows Price: Free License: Proprietary
NitroGit
Platforms: Windows Price: 20€/user / Free for non-commercial use License: Proprietary
GitFinder
Platforms: Mac Price: $24.95 License: Proprietary
Vershd
Platforms: Linux, Mac, Windows Price: Free trial, then $37 License: Proprietary
GitUI
Platforms: Linux, Mac, Windows Price: Free, but donations welcome License: MIT
Gitlab Download Mac Os X
Farkle frontend for Mac. GitLab Extension for Visual Studio. You can login any of your favorite GitLab servers and start your great job! The GitLab Extension for Visual Studio provides GitLab integration in Visual Studio 2015/2017/2019.Most of the extension UI lives in the Team Explorer pane, which is available from the View menu.
Download Gitlab Client For Mac
There are other great GUI tools available as well. Have a look at the list of interfaces, frontends and tools in the Git Wiki.