Git Visualizer is described as 'Provides an at-a-glance overview of the repository structure. Finer details can be explored via zooming and tooltips. It makes exploring large and complex projects a breeze'. There are six alternatives to Git Visualizer for Online / Web-based, Self-Hosted solutions, Mac, Windows and Linux. The best alternative is Gource, which is both free and Open Source. Other great apps like Git Visualizer are CodeFlower (Free, Open Source), Codeology (Free, Open Source), GitHub Visualizer (Free, Open Source) and Repography (Freemium).
Software projects are displayed by Gource as an animated tree with the root directory of the project at its centre. Directories appear as branches with files as leaves. Developers can be seen working on the tree at the times they contributed to the project.