XMPP is a zombie protocol. Yes, it has clients that have better implementation of instant messaging and presence than any other, but it falls apart with real t

XMPP is a zombie protocol. Yes, it has clients that have better implementation of instant messaging and presence than any other, but it falls apart with real time communication such as voice and video (lol jingle) and there is no practical way of iteroperating with the PSTN. Further, federation of plain text and basic presence worked, but rarely anything more. Connecting with federated users makes no sense to end users, first they have to know it is possible, then they have to figure out how it works and then they learn most features don't work. Even if that wasn't awful enough, it was all dropped by the providers and no longer works. All commercial platforms are moving away from the protocol, and SIP is now the standard. Problem is that it isn't a great chat protocol for end devices (no standard concept for buddy lists being stored on a server or mobile clients, but many proprietary extensions work well). As for slack, it is a group chat with slick interface, other than the bizarre account/domain design. It has no encryption of data at rest, and I really wouldn't use it for confidential data. If you are going to use a proprietary closed source solution, at least consider using Cisco Spark. Now Matrix, it is almost too good to be true, grass roots open standards, federation that makes sense, encryption by design and doesn't lock users into yet another captive island (YACI?). It is also built with the concepts of accounts/SSO, true federation, real time communications in mind. I dream of the day we can kill the PSTN, but with something even more open... Sadly none of the commercial players today are interested. Any one company that thinks they will do it on their own has fallen for their own delusions. Microsoft Skype, Whatsapp and a hapless Google Hangouts... What a mess.