I work on the OpenVidu development platform thus the Call application example was an easy recommendation... we have a public server with demo deployments, of which Call is just one.

Appear.in went through some changes (not sure of exactly what) and became "whereby" (sincerely the previous name was so much better).

Another all time favorite of mine (not self-hosted though) is talky.io

And of course there is Jitsi Meet, a very well-known get-a-room application that can also be self-hosted. And they maintain a public deployment too.