Open Source Windows Chat Software

BeeBEEP is a secure (encryption based on Rijndael Algorithm, AES) peer to peer office messenger. You can talk and send files with all your colleagues inside a local area network such of an office, home or internet cafe without a server. BeeBEEP works also with VPNs. This serverless application is indispensable in all those places where privacy and security an essential requirement. For more info visit: https://www.beebeep.net

DC++ is an open source Windows client for the Direct Connect file sharing network. The DC network is a decentralized network, made up of individual servers (hubs) that users join to share files with other members on that hub. Each hub is individually run by a fellow user of the DC network, and may have certain themes to the content on the hub. Hub owners set up rules to regulate their hub as they see fit.

Freenet front end written in Java. Supports multiple up/downloads, messages, searching and more.

Coccinella is a free and open-source cross-platform communication tool with a built-in whiteboard for improved collaboration with other people.

EZ Intranet Messenger is designed to work within a LAN segment, without the presence of centralized server. Its primary goal is to provide instant messaging service, along with online status notification, file transmission, and real time public chat.