Slack - A messaging app for teams who see through the Earth!
Twoo - With the millions of active and interesting people around the world, Twoo is one of the most interesting and practical means for finding the new people across the globe.
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.
Path Talk - Smart, Private Messaging
Wrinkl - Group messaging built for business
Qeep - If you are looking for a dedicated application freely allowing you to meet new people and find interesting friends, then Qeep is an application to whom you must give at least one try.