It's 2018, WebRTC is natively supported in all desktop & mobile browsers but still, most major players (Hangouts, Skype, appear.in, etc.) ask you to download their app to use the service.
Hello is a video chat app that works on most major desktop & mobile browsers. No Signup. No Downloads. Just video chat.
Hello uses WebRTC for video communication and a socket.io server that serves as a signaling server. It uses WebRTC mesh when more people are added to the call, it means each video stream in a group call uses a separate P2P connection. There is no hard limit on the number of people in the group video call, but the quality of the call will decrease when more than 5 people join the call.
Screen sharing is still not supported by all the browsers. The screen sharing button will be enabled only if the browser supports screen sharing. In Google Chrome (and in all chromium based browsers) you can enable screen sharing in chrome://flags/#enable-experimental-web-platform-features.
https://github.com/anoek/webrtc-group-chat-example
If you are here for checking the P2P video call without signaling server, head over to the gh-pages branch. And check out the demo here https://vasanthv.github.io/hello/.