Viber

Viber screenshots

Send messages, exchange files, and make voice and video calls.
Viber 6.6 : Main Window

Alternative downloads

Messages
9.0
FREE
iMessage lets you send messages to anyone on a Mac, or an iPhone, iPad, or iPod touch running iOS 5....
Telegram Desktop
1.9.9
FREE
The official app for Telegram cloud-based messaging service.
ChatMate for WhatsApp
4.3.1
Allows you to communicate and share files with others.