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!
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
LinkedIn Premium - LinkedIn is a social network helping brands and professionals to connect, identify sales prospects, hire talent, and promote their business.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
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.
Workplace by Facebook - Connect everyone in your company and turn ideas into action.