Sketch Repo - Collection of resources for anyone who uses Sketch
Invision - Prototyping and collaboration for design teams
Anima App - Design, get feedback, convert to code, publish, iterate.
Red Pen - Red Pen lets you upload your design, share a short URL, and get live, annotated feedback super-fast.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Pastel - Sticky note-based feedback collection tool for live websites