OmniFocus is described as 'Is designed to quickly capture your thoughts and ideas to store, manage, and help you process them into actionable to-do items' and is a very popular todo list manager in the office & productivity category. There are more than 100 alternatives to OmniFocus for a variety of platforms, including iPhone, Web-based, Android, Mac and iPad apps. The best OmniFocus alternative is Todoist, which is free. Other great apps like OmniFocus are TickTick, Workflowy, Quire and Remember The Milk.