Taskfully - Productivity reimagined
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Plan - Plan is a better way to organize.
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.
Taskade - Make lists, organize your thoughts, and be inspired to get things done. Taskade is a collaborative space for your tasks.
Google Tasks - to-do list app that integrates with Gmail and Google Calendar