No specific info about version 6.4. Please visit the main page of Trillian on Mac Informer.
Adium is a popular and, probably, the best instant messaging client for you Mac.
X-Chat Aqua is a freeware Mac OS X IRC client created by Steve Green.
Rocket.Chat is a Web Chat Server, developed in JavaScript.
Instant access to multiple Facebook accounts and desktop notifications.
Use Facebook Messenger right from your macOS desktop.