LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
MyChat - Secure instant messenger for any network
Drift - A messaging app that helps you grow your business.
BORGChat - BORGChat is a LAN messaging software program.
Crisp Chat - Multi-channel customer support software