Product School - The global leader in product management training
Viable Fit - Measure and improve your product market fit
The Product Manifesto - Product Managers face the biggest challenges of our day, which is why our community needs a common set of product principles.
OpinionX - Stack rank people's priorities in minutes with OpinionX's free ranking surveys.
Intercom on Product Management - The ultimate resource for aspiring product managers
Product Fit - Measure product/market fit in app with your users.