Taskful - Deadlines, meet your match.

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

Calendarist - Time blocking companion for Google Calendar

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.

Centered - Centered helps you get into a Flow State faster and stay there longer so you can do your best work.

Taskade - Make lists, organize your thoughts, and be inspired to get things done. Taskade is a collaborative space for your tasks.