You can integrate Converse.js into any of your website that using XMPP or Jabber server. Few ready made third party site plugin available, Plone, Django, Roundcube, WordPress, Patternslib and Alfresco.
Its provide single user chat, group chat and a lot of great features like single site log in, vCard support, service discovery, contact subscriptions, chat user statuses, typing notification, private off record encryption and more.
Converse.js is released under Mozilla Public license.
Source: Read more about Converse.js