productboard - Beautiful and powerful product management.
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.
Product Roadmap Builder by ProdPad - Make gorgeous drag & drop visual roadmaps
GoodGantt - The best Gantt chart for Trello®
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Paws for Trello - The best way to use Trello on your desktop