Anima App - Design, get feedback, convert to code, publish, iterate.
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Sketch Repo - Collection of resources for anyone who uses Sketch
Platforma - Wireframe library of layouts and UI elements
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
iOS Wireframing UX Kit - An easy, speedy way to wireframe for iOS