Hey superklevint! I explained our stack inside the Video room www.getnando.com/showhn and I'll do it here again:

We're using ReactJS with Redux which is really nice. It lets us pass data effortlessly and the whole ReactJS paradigm is just great.

We're using a couple of services -- Firebase to handle our coderpad and Sendbird to handle our chat.

Then we're using pretty vanilla webRTC to a server, so the peer connections aren't peer to peer, but peer to server to peer. This makes scalability better as well as connectivity (one guy who has really slow internet won't affect the group as much).

Then our application server is a simple NodeJS server that manages each individual room.