Workplace by Facebook - Connect everyone in your company and turn ideas into action.

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.

Bitrix24 - Bitrix24 is a free (for small businesses) social enterprise platform. It is a united work space which handles the many aspects of daily operations and tasks. Create your own social intranet in minutes!

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

LinkedIn Premium - LinkedIn is a social network helping brands and professionals to connect, identify sales prospects, hire talent, and promote their business.

Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.