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.

MyChat - Secure instant messenger for any network

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.

RealPopup.it - A network messaging application that's feature-rich yet easy-to-use and won't cost you a fortune, RealPopup LAN chat offers fast, stable messaging across your local network. No application server required, just install on your PC and start messaging!

BigAnt Office LAN Messenger - BigAnt Office LAN Messenger offers rich features for secure and stable business communication.