Fenetre App - Picture in picture for your mac.
Git Sketch Plugin - Version control for designers
Polarr Photo Editor 3 - The most powerful photo editor in the web.
Anima App - Design, get feedback, convert to code, publish, iterate.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.
Marvel for Sketch - Sync, play and record prototypes in Sketch!