Cryptocat is free software with a simple mission: everyone should be able to chat with their friends in privacy.
Open source.
All Cryptocat software is published transparently.
Encrypted by default. Every message is encrypted, always.
Forward secure. Chats are safe even if your keys are stolen.
Multiple devices.
Devices receive messages even when offline.
File sharing. Securely share files with friends.
link: https://crypto.cat