Chotr!

Free unlimited, anonymous, secure, encrypted and private messaging, including email type attachments, with your friends over the encrypted Chotr servers
Chotr stands for Chat OTR (Off The Record)

Chotr lets you chat just as easy as in MSN, Skype or Whatsapp — while you know your information does not fall into the wrong hands.
Only the sender and receiver can read a Chotr message. Even the attachments are fully encrypted.
Chotr is without a doubt the safest way to send text messages and documents or pictures.

Advantages
Easy to use!
Anonymous, no personal information required!
One step registration — You only need to enter an username and a password.
Free use of the encrypted xmpp servers.
Adding contacts with their username only.
Attachments can be saved private or public
Unencrypted messages are not possible!

Security
Without a doubt is Chotr the safest way to send text messages and attachments: it uses the strongest security and encryption protocol available: OTR (see https://en.wikipedia.org/wiki/Off-the-Record_Messaging). The AES algorithm, combined with the Diffie-Hellman protocol for exchanging keys, the SHA-1 hash cryptography and transport via TLS/SSL ensure an infallible security.
Chotr features extensive possibilities to delete chats and attachments, timer based. You can even wipe all information on your device with one menu button!