Startup Rocket By Buildily - The best startup tool kit for founders in one membership
Toolkit and Library for Designers - Create awesome designs with the best collection
JumpStart Toolkit - A pack of tools and goodies to jumpstart your startup
Checklist Design - The best UI and UX practices for production ready design.
Startup Toolkit - Interactive how-to guides to launch your startup
Design Principles - An open source repository of design principles and methods