LAN Messenger is an Open Source cross-platform instant messenger that allows server-less communications over local networks.

You will enjoy secure instant messaging with users within your network; AES encryption fully protects all messages with RSA. You can additionally send broadcast messages or send a notification to a specified user. Take advantage of smooth file transfers that enable the quick exchange of files - either for work or play. It also comes with multi-language support so you can set up the user interface to fit with most languages.

LAN Messenger also provides messaging logging so that you can quickly retrieve a past conversation when the need arises and best of all Internet access is not required making it safe from external threats.