YakYak - Desktop client for Google Hangouts
Signal - Fast, simple & secure messaging. Privacy that fits in your pocket.
Tragofone - White-label VoIP Softphone with WebRTC and Auto-provisioning
StealthChat - StealthChat is Encrypted, Private, Secure Calls and Chats on Android and Apple iOS
Lingo - Empower Creation and Ensure Brand Consistency. Build and Share libraries of visual assets with your entire team — all from your desktop.
Telegram - Telegram is a messaging app with a focus on speed and security. It’s superfast, simple and free.