OTP-Chat
OTP-Chat (client / server) YOUR PC is both client and server!
...The most important property of this solution is that NO "foreign" servers are required for communication.
When used correctly, the OTP is an information-theoretically secure and demonstrably non-breakable encryption.
By using an OTP-based key on both, the sender and recipient side, eavesdropping on chat communication, in terms of information theory, is impossible to poop. Correct use of the OTP is important. Details can be found in my project OPT-Crypto-Tool under Sourceforge.