Softros LAN messenger - LAN messenger for an internal office chat for home or business users. It does not require a server and is very easy to install and use. It supports personal chats, group chats, message brodcasting, files transfer and remote desktop access.
Bopup IM Suite - Organize secure messaging system and communicate instantly via self-hosted IM server.
BeeBEEP - You can message and share files inside your intranet without a server.
MyChat - Secure instant messenger for any network
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.