Slack - A messaging app for teams who see through the Earth!
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Microsoft Teams - Microsoft Teams provides the enterprise-level security, compliance and management features you expect from Office 365, including broad support for compliance standards, and eDiscovery and legal hold for channels, chats, and files.
Ripcord - A desktop chat client for Discord and Slack
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
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!