Gitscout - A beautiful Github Issues experience for macOS
Mergefly - A modern UI for GitHub pull requests
Codetree - You can manage your entire development process through GitHub.
PullRequest.com - Code review as a service
Shrink for Github - A macOS app for your Github issues
Codementor - “Instant help from expert developers. Codementor is your instant 1:1 expert mentor helping you in real time.”