UpDiagram - Free agile project management tool for scrum team
Software Product Management Stack - Resources & tools to help you manage your software product
Chpokify - Planning Poker Tool that saves time of sprint estimation. Agile teams management tools. Jira Integration (Import/Export), auto-summary, smart voting management.
The Product Management guide - A book on how to create and ship products that people love
HeyScrum - Over 1500+ realistic exams questions to help you pass any Agile and Scrum certification on the FIRST try.
Product Management Exercises - A repository of product manager job interview exercises