Invision - Prototyping and collaboration for design teams
Anima App - Design, get feedback, convert to code, publish, iterate.
Marvel - Turn sketches, mockups and designs into web, iPhone, iOS, Android and Apple Watch app prototypes.
Sketch Repo - Collection of resources for anyone who uses Sketch
Adobe XD - Adobe XD is an all-in-one UX/UI solution for designing websites, mobile apps and more.
Auto-Layout for Sketch - Responsive design for Sketch