userinput.io - Get on-demand feedback for your app, website or idea. Learn how to improve by hearing real opinions.
Intercom on Product Management - The ultimate resource for aspiring product managers
Upvoty - User feedback in 1 simple overview 🔥
Product School - The global leader in product management training
Instabug for Product Managers - Collect and understand user feedback
The Product Management guide - A book on how to create and ship products that people love