Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
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.
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
Notion - All-in-one workspace. One tool for your whole team. Write, plan, and get organized.
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.
Slack - A messaging app for teams who see through the Earth!