Jitsi is an application for video conferencing. It is browser based, so no extra software needs to be installed on your computer (Free apps are available for iOS, Android, MacOS and Windows)
There are numerous Jitsi servers are available for public use.
Here is a short instruction for the operation --> Jitsi - quick guide
» Go ahead, video chat with the whole team. In fact, invite everyone you know. Jitsi Meet is a fully encrypted, 100% open source video conferencing solution that you can use all day, every day, for free — with no account needed. « (https://jitsi.org/jitsi-meet/)