Review Board

A collaborative code review tool that lets teams post changes as review requests, comment on individual lines, and approve or reject work before it is merged. It works with Git, Mercurial, Subversion and Perforce, and adds things plain pull request pages lack, including side-by-side diffs that detect moved lines, Markdown comments, status tracking and a command line client for posting changes.

Engineering teams use it to keep reviews in a central queue and to preserve a searchable record of past discussions.

Hosting it internally means proprietary code and comments stay on infrastructure you control, costs do not scale with the number of reviewers, and review history is yours to back up and restore.