eXo Platform - Digital workplace solution

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

Basecamp - A simple and elegant project management system.

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

Slack - A messaging app for teams who see through the Earth!

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.