<a href="http:&#x2F;&#x2F;getkaiwa.com&#x2F;" rel="nofollow">http:&#x2F;&#x2F;getkaiwa.com&#x2F;</a> is another Slack alternative that uses an XMPP backend, which IMO is much better than a custom backend. So far the only open source Slack clone I&#x27;ve seen that uses an existing standard for the backend