I don't understand why even most of the open-source projects aren't using a modern standard like XMPP, and simply focusing on the UX.

Is there a technical reason for it? Is XMPP broken in some way? Or is the chat space simply full of pathological cases of Not-Built-Here Syndrome?

Does XMPP support inline photo and video? Last I checked, it didn't. So why deal with the external dependency when you can re-write it yourself with additional features?

It does according to Wikipedia, although "Binary data must be first base64 encoded before it can be transmitted in-band", making it inefficient[1].

XMPP's based on XML anyway, so implementing inline media and extra features sounds easier than rolling an entirely new protocol.

But perhaps some of the proprietary systems use XMPP internally anyway? After all, it's used for more than just chat clients nowadays.

[1]: https://en.wikipedia.org/wiki/Xmpp#Weaknesses

Slack is amazing. We dumped HipChat which had been in beta for 4 years! Slack had good iPhone integration (HipChat would bot give me notifications?!) Really useful integration with Trello.

Flowdock has changed the way that we do things - it is so much more than chat.

Haven't personally tried it but maybe check out Slack

Everyone has been raving about it. Just raised $42 million today too.

what about http://gitter.im?