ChatS - Chat with your friends securely and secretly by self-encrypted communication.
Easy to use messenger tool that use encryption/decryption techniques to only send coded messages free via the web.
You chose the encryption key, stored encrypted on your device using a Password potentially stored nowhere, and that only you know.
Send the messages encoded, and decoded by a PasCode only you and your friend, the recipient, knows.

XMPP Jabber Client is a amazing free and open source client for android.

Free Block Call and Block SMS. helps manage a blacklist and whitelist. If you are looking for a call blocker and SMS blocker. this application is what you need.

Push To Talk Walkie Talkie Voice Communication Free App.

myMail brings all your email accounts into one simple, bright, and friendly interface.

The myMail app is 100% free, regardless of the number of accounts you add.