Secure, server-less, and supports group chats and file sharing. TrueConf Info

A free, open-source LAN messenger that is easy to deploy without complex configuration. GitHub

: A primary focus is often on data privacy. Many proposed systems implement End-to-End Encryption (E2EE) using keys to ensure that sensitive data never leaves the local network.

LAN (Local Area Network) chat software enables real-time communication within a closed network, often without requiring a server or an internet connection. These applications are frequently the subject of academic papers and project reports due to their use of and TCP/IP protocols to manage peer-to-peer or client-server interactions. Core Concepts in LAN Chat Papers

Popular for office environments; supports remote desktop and group rooms (Free trial/version often available). Microsoft Store Key Research Resources

Research papers on this topic typically focus on the following technical areas:

If you are looking to download and study existing implementations, several free and open-source options are widely cited: