Gerrit is a web based code review and project management for Git based projects.
Gerrit is a web based code review system, facilitating online code reviews for projects using the Git version control system.
Gerrit makes reviews easier by showing changes in a side-by-side display, and allowing inline comments to be added by any reviewer.
Gerrit is not only a review interface but it's able to manage git repository into is core. To keep an external git repository, it is recommended to use replication plugin. Replication plugin documentation.
Gerrit2 is a complete rewrite of the Gerrit fork, completely changing the implementation from Python on Google App Engine, to Java on a J2EE servlet container and a SQL database.