ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
Product School - The global leader in product management training
Clearbit - Clearbit provides Business Intelligence APIs
Software Product Management Stack - Resources & tools to help you manage your software product
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.
PM Starter Pack - Practical guide on how to get started in product management