Flinto - The prototyping tool designers have been waiting for.
Software Product Management Stack - Resources & tools to help you manage your software product
Base UI Sketch Framework - Huge set of everything you need to design and prototype
The Product Management guide - A book on how to create and ship products that people love
Glyphy - Copy & paste fancy fonts + cool symbols ☞✺✐™
Product Management Exercises - A repository of product manager job interview exercises