Gitscout - A beautiful Github Issues experience for macOS
CodeStream - CodeStream helps development teams resolve issues faster, and improve code quality by streamlining code reviews inside your IDE
Codetree - You can manage your entire development process through GitHub.
codebeat - Automated code review for Swift
Shrink for Github - A macOS app for your Github issues
Codacy - Automatically reviews code style, security, duplication, complexity, and coverage on every change while tracking code quality throughout your sprints.