Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Whimsical Wireframes - Lightning fast wireframing with real-time collaboration.
Module 02: Layouts - Professional toolkit for UI/UX design
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
Startup Toolkit - Interactive how-to guides to launch your startup
Easometric Figma Plugin - With Easometric it's really easy to create isometric layers.