Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Mockup Generator - Create attractive product screenshots with just a few clicks
Platforma - Wireframe library of layouts and UI elements
shotsnapp - Create beautiful device mockup presentation