Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Empathy - Apps/Empathy - GNOME Wiki!
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Psi-IM - Psi-IM is a messaging program that is designed for the XMPP network.
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
Gajim - Full featured and easy to use Jabber client