What is Mergeable
The “Pull Requests” page provided by GitHub is not flexible enough to efficiently track pull requests. It is impossible to add or remove tabs, switching between tabs is slow, and there is no unified view of all pull requests. Moreover, it is difficult for a user to know whether they need to take action on a particular pull request without opening it.
Mergeable is meant to be a better inbox for GitHub pull requests, that displays all pull requests of interest on a single page in a very flexible manner: