Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.

Todoist - Todoist is a to-do list that helps you get organized, at work and in life.

Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.

Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.

Obsidian Flight School - 🚀Obsidian Flight School is an educational product—and starter kit.

EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.