Platforma - Wireframe library of layouts and UI elements
FlowMapp - FlowMapp is a UX planning tool for creating visual sitemaps and user flow.
Contra Wireframe Kit - Open source wireframe kit for design and prototyping 🚀
Really Good UX - A library of screenshots for UX inspiration
Source Wireframe Kit - Library of 537 blocks for desktop and mobile prototyping
UX Recipe for iOS - Design checklist & estimation tool for your next UX project