Top rated in Instant Messaging & VoIP
Send instant messages, share files, and hold video conferences.
iMessage lets you send messages to anyone on a Mac, or an iPhone, iPad...
Send messages, have group chats, and share pictures using the Whatsapp services.
Do more than just IM with Yahoo!
A desktop messenger that allows using the services of Telegram.
A chat-based workspace in Office 365 with private group conversations.
Popular and, probably, the best instant messaging client for you Mac.
Send messages, make video calls and stay connected with your friends.
Send messages, exchange files, and make voice and video calls.
Free-to-use voice and text chat application for gamers.
Video chat/calling tool; see up to 6 friends at once.
QQ connects you to over 600 million Chinese QQ members and many of your favorite websites and useful tools.
VoIP program which allows you to make phone calls over the internet.
Integrated functionality for instant messaging, presence, conferencing and voice.
Communicate with all of your friends personally and in group chats on your Mac just as you would with your mobile device.
Stay in touch with your colleagues and monitor conversations.
Powerful and efficient instant messaging client.
Spark is an open source, cross-platform instant messaging client for businesses.
iGlasses allows you to adjust and manipulate your webcam's video settings.
Traditionally, chat clients on the Mac have been anything but glamorous.
Google, Skype, Yahoo, MSN, AIM, Jabber, Facebook, SMS, Fax...
Supports private and group communication as well as file exchanges.
Freeware Mac OS X IRC client created by Steve Green.
Chat application that tries to integrate most of the major chat networks into one application.