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.
VOGSY - Professional service automation tool built on Google G Suite
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Office Timesheets - Professional Services Automation
Remember The Milk - Remember The Milk is a task and time management application for mobile devices.