PrepBootstrap - Bootstrap themes, templates & widgets with code examples
Sketch Mirror - Preview your iOS designs directly on your devices
Start Bootstrap - Bootstrap Themes, Templates, Snippets, and Guides
Figma Mirror - Figma Mirror is an application that covers top trending designing or sketching ideas making your teamwork in a single environment and design better products from start to finish.
WrapBootstrap - WrapBootstrap is a marketplace for premium Bootstrap themes and templates.
Flowkit - Sketch library for user flows/content maps/annotations