Review Board is a powerful open source web-based code review tool that offers developers an easy way to handle code reviews. It's used in several open source projects, including parts of KDE, as well as many startups and large companies, including Twitter and Yahoo, helping them to write better code and more stable products.

Review Board is built on top of Python and Django. It works on Linux, Windows and MacOS X, and supports a wide variety of source code management systems, including Subversion, CVS, Perforce, Git, Mercurial, Bazaar, and ClearCase.