DeepSource - Automated code reviews with static analysis.
Codacy - Automatically reviews code style, security, duplication, complexity, and coverage on every change while tracking code quality throughout your sprints.
JavaScript Operator Lookup - A full list of JavaScript operators with examples
JavaScripting - Ranking of top JavaScript libraries, frameworks, and plugins
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.
Codebeat for iOS - Automated code review for iOS