AnonChat - Anonymous LAN Chat for Android
You can chat in groups between users of your local network (WiFi - LAN) without external servers, so will not spend even a single MB of your internet connection and thus have the assurance that your conversations will never be seen by people outside your network.
[*] No user lists.
[*] No warnings connections.
[*] Fully encrypted traffic.
The distinction between users is done via an Alias (optional) and using IP or Host device.
Users with open application receive messages, no messages queued or servers that store the messages.