BeeBEEP

BeeBEEP is an open source, peer to peer, lan messenger developed by
Marco Mastroddi. You can talk and share files with all the people
inside your local area network such of an office, home or internet cafe.
You don't need a server, just download and start it.
Simple, fast and secure.

You can find the upstream homepage at http://beebeep.net/

To allow the app access to removable devices, you can connect the removable-media
snap plug using the command sudo snap connect beebeep:removable-media