If you’re seeing this then either the the Converse.js XMPP chat application we use here hasn’t loaded yet, or couldn’t be loaded. Maybe you disabled JavaScript, in which case we respect that, maybe there was a problem loading it, or maybe you just need to wait just a moment longer.
Here are some other XMPP clients you could try, if you already have an XMPP account:
The address to join here is modernxmpp@rooms.modernxmpp.org.