GitLab – Open Source Git Management Software
We use and love Atlassian Stash (https://www.atlassian.com/software/stash), it's excellent for code reviews. The diff view options and commenting make it easy to create pull requests, get feedback and eventually merge code into the master branch. (Per branch permissions are awesome too.)Long time ago we also assessed GitLab and found it usable but not quite there yet for production use. Though it looks nicer now.