DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
Rectangle - Window management app based on Spectacle, written in Swift.
Mizage Divvy - Divvy is an entirely new way of managing your workspace.
WindowGrid - Quickly and easily layout windows on a dynamic grid using just the mouse.
Swish - Insanely great window management
Shiftit - fikovnik has 62 repositories available. Follow their code on GitHub.