Signal Private Messenger

Signal is a social networking app from Open Whisper Systems for easy and reliable communication, which is exclusively available for iOS users for free. It offers you numerous ways of conversation without compromising your privacy.

Highlights:

• Gossip with your friends or discuss official work with your colleagues with complete privacy. One-on-one conversations and group chats are secured with end-to-end encryption protocol. 
• Signal is the only messaging service with Open Source that enables the user to verify security by inspecting the code.
• Make phone calls having crystal clear voice quality across the globe without any extra charge.

Signal is compatible with iOS 8.0 and later versions. Download Signal for seamless and effective communication with complete privacy. 

Pros

End-to-end encryption; crystal clear voice quality for your phone calls.

Cons

Not compatible with Android.