Jitsi Meet, but be aware that unless you are running it on a desktop in a chromium based browser, or its desktop app then it will not have end-to-end encryption as an option.
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Jitsi Meet?
+1 for Jitsi. Works well, user-friendly, lots of features without looking complicated, not too resource-hungry, lots of ways to extend it. All the other person needs it to click a link, enter a name and allow microphone/camera usage one time. There's also an app for Android and iOS, though you can just as well use a mobile browser.
I have a small self-hosted Nextcloud with Nextcloud Chat and it can do video though it isn't great. Jitsi Meet is much better but I haven't tried to host it myself. I'm sure there are other options too, though idk what to suggest. Maybe see what's around on Scriptaculous these days?
vdo.ninja?
element call
- no need to create an account
- mobile-friendly web app
I could be wrong but I'm pretty sure WebKit for iOS heavily restricts the capabilities of webapps, finding an application that meets any or all of this criteria for iOS users is unlikely in my opinion. I assumed you already considered Jami and Jitsi Meet but maybe you can consider Signal? It's not as mainstream as WhatsApp but it's still pretty popular. Depending on where you live and the type of people you're talking to, I'd say there's like a 5-20% chance some people you'll meet already have it.