Slack showcases the HIPAA logo on their security page, but upon closer inspection - https://slack.com/terms-of-service/supplement#healthcare - you'll see that unless you've signed a separate agreement with them, you acknowledge that Slack is not HIPAA compliant and that you are not to send them any PHI. My guess: they are signing BAAs for grid customers only (so the logo isn't a lie) and making them pay handsomely for the pleasure.
As I shamelessly disclosed upthread, we (Trillian) offer a HITRUST certified, BAA-backed solution for healthcare organizations that comes in SaaS and on-prem variants. More: https://trillian.im/uses/hipaa-compliant-texting/
We think integrations can be great, and offer a few of our own right now (a proof-of-concept /weather command and a deeper integration with Global Relay for some of our fintech customers, for example). That being said, we're being careful about integrations and making sure they're more than just novelties that do nothing but move email notifications into a group chat. Our primary focus is lean and mean instant messaging, the good old contact list + presence (with ICQ-era fun like invisibility allow lists!), speed (being one of the last few companies offering a desktop chat client written in C++ that chugs along without using 2GB of RAM!), and strong administrative controls. Secondary to that is our focus on integrations that bring clear value to our customers. I expect we'll add more good ones this year!
Shameless self-promotion: We (Trillian) just received HITRUST certification, provide a BAA, and offer both a SaaS variant and the self-hosted Trillian Server product, both of which run over our own open IM protocol. We're not exactly a Slack/Hipchat clone (having been around for 18+ years, we're more of a traditional IM and group chat solution with some modern stuff like an API, chat bots, and federation capabilities) but have been getting great feedback in the healthcare space with our business offering. More: https://trillian.im/uses/hipaa-compliant-texting/
Because this isn't a new project for us; if it was, we'd absolutely be using XMPP. Our choices were to dump 10+ years of engineering and spend another two trying to wrangle XMPP to fit our needs (and do so across Windows, Mac, iOS, Android, BlackBerry, and Web), to keep our protocol but publish docs, or to continue to run yet-another-walled-garden.
The maker of an interoperable IM client not running an interoperable IM protocol just felt silly to us, so we decided to spend a week and publish something.
Yeah, inertia. What we've tried to do with IMPP is to roll all of the features that IM users actually want into the core protocol versus just saying "it's open!" or "it can be extended!" and hoping someone else does the dirty work. We build the server side and we build the client side, which is important; it means we're not off dreaming up pie-in-the-sky features that would be absolutely horrible for a client developer to implemement.
We have some experience reverse engineering the rest of the IM protocols out there as well, and they all have their own issues which we kept in mind when building ours. At the end of the day, our actual motivations were simple: publishing the protocol is the right thing to do and so we did it. It's been on our TODO for 6+ years. :)
1) We are obviously aware of XMPP, having been developing client-side interfaces to it for years.
2) We started this project in 2001 - around the same time Jabber was in its infancy - and as smacktoward notes, the main reason we're not using XMPP today is inertia. XMPP is great, but XML just isn't our personal preference.
We figure being more open with our protocol can't be a bad thing and so it's out there for folks to pick apart and send us feedback, which we'd love! Alot of our protocol was built with an eye towards XMPP federation as well; I actually had Trillian interoperating with Google Talk one afternoon but it seems like that ship may have sailed. :-\
As I shamelessly disclosed upthread, we (Trillian) offer a HITRUST certified, BAA-backed solution for healthcare organizations that comes in SaaS and on-prem variants. More: https://trillian.im/uses/hipaa-compliant-texting/