Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
productboard - Beautiful and powerful product management.
Tables by Google - Tables helps teams easily track & automate tasks
ProductPlan - Cloud-based product roadmap software solution
Project Plan Notion Template - A project plan is essential for successful strategy development.
ProdPad - ProdPad helps your team gather ideas, surface the best ones and turn them into product specs, and then put it all on a product roadmap.