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.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Standard Notes - A safe place for your notes, thoughts, and life's work
Any.DO - The #1 task management app used by over 11 million people globally, Any.do is your free mobile and online task manager for Android, iPhone, Web and more.
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.
Microsoft To-Do - Task management tool