Nifty - Manage projects, work, and communications in one place.
Gitscout - A beautiful Github Issues experience for macOS
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
GitHub Reader - A quick way to browse GitHub issues and pull requests.
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.
VarCI - The missing assistant For GitHub issues