Platforma - Wireframe library of layouts and UI elements
MockMagic - A free, easy-to-use device mockup generator
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Smart Watch UI Kit - Helps smartwatch designers to design easily, 52 design
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Module 02: Layouts - Professional toolkit for UI/UX design