BeeBEEP - You can message and share files inside your intranet without a server.
LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
Feem - Share files offline. No servers. No cloud. No limits.
Output Messenger - Secure instant messenger app for office provides seamless instant messaging solutions for all office, corporate and enterprise business communication needs.
Bopup IM Suite - Organize secure messaging system and communicate instantly via self-hosted IM server.
Winpopup LAN Messenger - Winpopup LAN Messenger is a cost-effective Office, Corporate, Enterprise Instant Messaging solution.