There are several ways to install Git on a Mac. The easiest is probably to install the Xcode Command Line Tools. On Mavericks (10.9) or above you can do this simply. The open source version can override the version that comes standard with shipped Revit. Revit 2013-2018 contain both IFC export and IFC export UI overrides, which contain options not available in the regular UI, such as ifcXML and ifcZIP support. The Revit 2014-2018 versions also work.
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.
Git For Mac Gui
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
There are other great GUI tools available as well. Have a look at the list of interfaces, frontends and tools in the Git Wiki.
There are several options for installing Git on macOS. Note that any non-source distributions are provided by third parties, and may not be up to date with the latest source release.
Homebrew
Github Gui
Install homebrew if you don't already have it, then: $ brew install git
Xcode
Apple ships a binary package of Git with Xcode.
Binary installer
Tim Harper provides an installer for Git. The latest version is 2.27.0, which was released 3 months ago, on 2020-07-22.
Building from Source
Best Git Gui Mac
If you prefer to build from source, you can find tarballs on kernel.org. The latest version is 2.28.0.