CodeStream - CodeStream helps development teams resolve issues faster, and improve code quality by streamlining code reviews inside your IDE
Mergefly - A modern UI for GitHub pull requests
codebeat - Automated code review for Swift
PullRequest.com - Code review as a service
Codacy - Automatically reviews code style, security, duplication, complexity, and coverage on every change while tracking code quality throughout your sprints.
Codementor - “Instant help from expert developers. Codementor is your instant 1:1 expert mentor helping you in real time.”