Alternative to Zoom: https://meet.jit.si/
Fun fact: Jisti Meet is also not end-to-end encrypted despite misleading marketing:
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. (Source)
WebRTC does not (yet) provide a way of conducting multi-party conversations with end-to-end encryption. Unless you consistently compare DTLS fingerprints with your peers vocally, the same goes for one-to-one calls. As a result, your stream is encrypted on the network but decrypted on the machine that hosts the bridge when using Jitsi Meet. (Source)
In summary, server-side parties can monitor/record your calls when using Jitsi Meet. We contacted several bloggers and news agencies (like ORF) that mistakenly reported Jitsi is always end-to-end encrypted.
As always, if a service doesn’t provide end-to-end encryption, you could try to host the server component yourself. However, most people don’t do it.