Anima App - Design, get feedback, convert to code, publish, iterate.
Maze - Beautiful & actionable analytics for InVision prototypes
Sketch Repo - Collection of resources for anyone who uses Sketch
ProtoPie - ProtoPie is the easiest tool used to turn your UI/UX design ideas into highly interactive prototypes for mobile, desktop, web, all the way to IoT.
Git Sketch Plugin - Version control for designers
W3C Mobile Checker - Make websites work better on mobile devices