Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Invision - Prototyping and collaboration for design teams
Platforma - Wireframe library of layouts and UI elements
Mockuuups Studio - Fast and easy way to create product mockups on macOS, Windows and Linux.
Craftwork - A collection of User Interface resources made by Craftwork
Method Wireframe Kit - Find your method of being incredibly fast in prototyping.