If you're already strong with Git at the command line, these GUI clients may not be your cup of tea. For beginners and intermediate users, these Git GUI clients are a good place to begin with.
Thoroughly test each of these GUI clients with large repositories and measure their performance. Shortlist the ones capable of handling these large repos with ease. Pick one of the shortlisted.
Graphical GitHub Client for Windows- Light and impressive interface - As I mentioned before, its interface is very good and the application itself is lightning fast consuming very less system resources.
- Actively updated - It has a very active development life cycle and new features are added to the application on a regular basis making it more powerful than its predecessor.
- Free to use - The best part is that it is completely free of cost with no restrictions so one can use it without spending a single dime.
- Works seamlessly - Since I'm an avid user of this client I never faced any usage issue till date while working and managing my projects through this powerful program.
Graphical GitHub Client for Mac OS X- One click operations - As mentioned before, one can easily complete multi-step operations through a single click while working with this Git client.
- Free to use - Needless to say, this Mac based client is free as well like its Window based sibling.
- Active development cycle - This client has the same agile and active development life cycle which includes addition of key features and improvement of the existing ones.
- Lightning fast - The application itself is a zipper and runs smoothly even on Mac systems with old configurations.
SourceTree Git App- Perfect for beginners - If you've never used Git before or just starting with it, this is the perfect Git client to start with.
- Connects with multiple services - It is one of the few clients which include support of integration with popular Git flavored services.
- Supports advanced operations - Powers users can easily take advantage of all the advanced Git options baked right inside this awesome client.
- Free to use - And, this is yet another free Git client one can use without any restrictions with awesome new features added in each update.
Gitbox Git client for Mac OS X- Stunning interface - Like every premium application, this Git client has an excellent interface with easy-to-use controls.
- Powerful search - Its repository search is very powerful and can find information in a large project repository, almost instantly.
- Advanced Git workflow - Power users can take all the advantage of advanced Git commands supported by this application.
- Handy keyboard shortcuts - It also has a rich collection of keyboard shortcuts to help you get things done in a quick way.
Tower Git Client for Mac OS X- One click operations - All standard and advanced Git commands can be completed in a single click while working with this application.
- Automate selective tasks - Power users can also automate certain Git workflows to save time as well as to improve the entire workflow.
- Clone in background - For very large projects, you can trigger cloning of repositories in the background while you work on other areas of the project.
- Drag & drop support - Apart from point and click task completion, one can also take advantage of drag & drop feature to complete all the Git commands.
SmartGit Git Client- Markdown support - All Markdown files in your project can be viewed in the supported format directly within this client without any need to rely on external viewer.
- Optimized file comparison - It has one of the best file comparison utility that can clearly highlight the changes made throughout the file history.
- Built-in SSH client - It also has a SSH client to easily connect with remote servers without leaving the application at all.
- Custom commands - Power users can also integrate external tools by specifying custom commands and adding the options directly within the application's interface.
git-cola Git Client for all Platforms- Light and blazing fast - The moment you'll start using this Git client, you'll realize that it's comparatively very light on system resources.
- Free to use - This is yet another free to use graphical Git client without any kind of hidden restrictions.
- Command line support - Power user can also take advantage of its support for useful and flexible command line options to speed up the tasks.
- Configurable logging options - Users can also instruct the application to generate custom log files matching with your needs.
GitEye Graphical Git Client- Excellent interface - It has a powerful and feature packed interface which allows even beginners to manage repositories with ease.
- User friendly history management - One can easily go back to the timeline to easily track, observe and edit the change made in the repository.
- Dedicated support - Since it is a premium solution, you'll get exceptional support to get more out of this Git client.
- Maintenance free - This application receives major updates and patches in the background so you're free of worrying about updating this Git client.

GitUp - Mac users can also try out this feature-packed Git client which includes some user friendly features. Its blame viewer is one of the best and allows team leaders to inspect file change history in a better way while working with large teams. Handy redo option allows newbies to revert to the old state without worrying about changes made inadvertently. Make sure you're running Mac OS X 10.6+ to run this Git client. Its file filter function allows you to quickly locate files in a large collapsed source tree. So, let's see some of its features and functions one can use to manage his Git repositories.
- Easy conflict resolving - Users often panic whenever a branch conflict arises while working with repositories. This application help you resolve it in an easy way.
- Powerful file history viewer - Each team member can view the complete file change history in two different formats.
- Live map - Easy map visualization of the entire repository ensures you can easily pick and choose the work area without any issues.
- Quick shortcut keys - Power users can master the shortcut keys to complete the tasks at a lightning pace saving lot of time.
GitX-dev Git Client for Mac OS X- Less memory usage - I've tested it thoroughly and found that is it very memory efficient and works seamlessly on low end machines too.
- Integrated command line tool - Professionals and power users can take the advantage of its command line module to perform complex tasks with ease.
- Author & revision based search - Team leaders can easily perform quick search within repository based on specific author and revision history.
- Easy source tree scanning - The user friendly interface facilitates quick and easy scanning of a large source tree.