Git - Git is a free and open source version control system designed to handle everything from small to very large projects with speed and efficiency. It is easy to learn and lightweight with lighting fast performance that outclasses competitors.
Code Review by Codementor - Get an expert to review your code on-demand
Mercurial SCM - Mercurial is a free, distributed source control management tool.
Codacy - Automatically reviews code style, security, duplication, complexity, and coverage on every change while tracking code quality throughout your sprints.
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
PullRequest.com - Code review as a service