There is Matrix (https://matrix.org https://matrix.org) which now integrates nicely with Jitsi (https://jitsi.org https://jitsi.org). There's also BigBlueButton

There is Matrix (https://matrix.org https://matrix.org) which now integrates nicely with Jitsi (https://jitsi.org https://jitsi.org). There's also BigBlueButton (https://bigbluebutton.org https://bigbluebutton.org).