The best open source alternative to Veyon is Epoptes, which is both free and Open Source. If that doesn't work for you, our users have ranked more than 10 alternatives to Veyon, but unfortunately only two of them is open source.
Epoptes is an open source computer lab management and monitoring tool. It allows for screen broadcasting and monitoring, remote command execution, message sending, imposing restrictions like screen locking or sound muting the clients and much more!
Free Open-Source Remote Administration Tool for Windows Quasar is a fast and light-weight remote administration tool coded in C#. Providing high stability and an easy-to-use user interface, Quasar the perfect remote administration solution for you.