Nifty - Manage projects, work, and communications in one place.
Anima App - Design, get feedback, convert to code, publish, iterate.
UnderPinned - One app to manage your projects from start to finish.
Sketch Repo - Collection of resources for anyone who uses Sketch
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.
Auto-Layout for Sketch - Responsive design for Sketch