Snapchat - Real-time picture chatting
Slack - A messaging app for teams who see through the Earth!
Element.io - Secure messaging app with strong end-to-end encryption, advanced group chat privacy settings, secure video calls for teams, encrypted communication using Matrix open network. Riot.im is now Element.
Standuply - Run daily standup meetings and track your metrics in Slack
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
Glide 3 - Lightning fast live video messaging