RuboCop - A Ruby static code analyzer, based on the community Ruby style guide.
Gerrit Code Review - OpenSource Git Code Review Tool
SonarQube - SonarQube, a core component of the Sonar solution, is an open source, self-managed tool that systematically helps developers and organizations deliver Clean Code.
Phabricator - Phacility - Phabricator
ESLint - The fully pluggable JavaScript code quality tool
GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.