One more thing:
Freenode has given me about ~20 slots to work with on this demo. If you can't connect, try another network, like `irc.rizon.net` or something.
KiwiIRC uses this protocol apparently. I asked the author about it and they said they have worked out special arrangements with some networks to implement it, and accept connections exclusively from Kiwi, I presume? After all, a password is required according to this spec:
https://kiwiirc.com/docs/webirc
The 20 slot limit being mentioned is just in regards to the demo connecting to freenode. The demo connects to freenode from a single IP address and freenode has limits on how many connections you can have from one IP. It's not something you need to worry about in a normal use-case.
This is a really good looking web IRC client and it works so well with notification sounds, favicon updates etc.