Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.
PowerSchool - PowerSchool provides a K-12 education technology platform for operations, classroom, student growth, and family engagement.
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.