Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
Teachable - Create and sell beautiful online courses with the platform used by the best online entrepreneurs to sell $100m+ to over 4 million students worldwide.
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.
Clever - syncing between education applications for K-12 schools
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Claroline - Claroline is a collaborative eLearning and eWorking platform.