Astrid is described as 'At its core, Astrid is a open source todo list that helps you get stuff done. That's why Astrid makes it really easy to create lists of tasks, as well as set priority, set due dates, and times' and is a popular todo list manager in the office & productivity category. There are more than 100 alternatives to Astrid for a variety of platforms, including Windows, Web-based, Android, iPhone and Mac apps. The best Astrid alternative is Todoist, which is free. Other great apps like Astrid are Tasks.org, TickTick, Workflowy and Habitica.