Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Streaks - The to-do list that helps you form good habits.
tawk.to - tawk.to is a free live chat app that lets you monitor and chat with visitors on your website or from a free customizable page
Taskful - Deadlines, meet your match.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
ToDoList - Windows desktop application to stay on top of your daily tasks.