Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
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.
Facebook Messenger - Facebook Messenger is a faster way to message.
Jitsi - Open-source video calling and chat platform.
Cotap - Cotap is a simple, secure mobile messaging app for fast, easy workplace communication.
LINE - LINE is a Japanese proprietary application for instant messaging on smartphones and PCs.