Tower is described as 'Native desktop Git client for macOS and Windows with Pull Requests, Interactive Rebase, Image Diffing, Undo, and quick actions, integrating with all major code hosting services' and is a popular Version Control system in the development category. There are more than 50 alternatives to Tower for a variety of platforms, including Mac, Windows, Linux, Android and Flathub apps. The best Tower alternative is GitHub Desktop, which is both free and Open Source. Other great apps like Tower are SmartGit, Sourcetree, GitKraken and Fork.
Sublime Merge is free, but a license must be purchased for contuined use, however, its features and design are by far, the best you can get at 0$ price