Jitsi Meet
5.0 o 5 mau hōkū (ma muli o 2 hōʻike manaʻo)
Jitsi Meet is an open-source (Apache) WebRTC JavaScript application that uses Jitsi Videobridge to provide high quality, secure and scalable video conferences. Jitsi Meet allows very efficient collaboration. Users can stream their desktop or only some windows. It also supports shared document editing with Etherpad.
You can install jitsi on your own server and tweak it as you want. The software itself is indeed trade-free.