Todoist - Todoist is a to-do list that helps you get organized, at work and in life.

Gone - An ephemeral to-do list

doo - A smart, simple app for reminders and to-dos

Simpli - Keep track of email, calendars, notes and more in a unified interface.

Laverna - Laverna is a JavaScript note taking application with Markdown editor and encryption support.

RescueTime - Time management software that shows you how you spend your time & provides tools to help you be more productive.