Trello is a free project management tool that helps you get organized. It shows a board on which you can create lists filled with cards. When you open a card, you can add comments, upload files, create checklists, and more.
It is super versatile, so it can be used for many different types of things: to organize a specific project, write an ebook, create an email course, etc. It really helps you to keep a bird’s-eye view on your projects.