Such as? If you've got less than 1000 users then you need an extremely basic server, a raspberry pi should more than suffice. Then you've just got a little bit of manual (or automated) administration, software updates and backups mostly.
I really didn't expect my post to be so controversial, is the HN crowd really so terrified about running there own hardware?
I'm guessing that you're being downvoted because there's a lot more to consider. I agree that it doesn't take much hardware these days (most single-board computers would work perfectly well) to service <1k simultaneous chat users with efficient server-side software (e.g. UnrealIRCd or ejabberd). However, to make it as reliable as Slack (99.99% monthly uptime is their SLA) for the price they offer it ( https://www.slack.com/plans ) would likely take considerable engineering effort. Sure, you could set it up, toss it in a closet, and it might have 100% uptime for a year...until it doesn't. If chat is business-critical, there are chat companies that have profit motive to deliver a good service. If chat is a nice-to-have at a company (and you e.g. don't have to worry about data retention laws / compliance stuff), maybe it's fine to run it on an rPi / t2.micro (free) AWS instance.
Luckily, there are a ton of great free and paid options out there these days!
For $6670 a month (price for 1000 users), I’m pretty sure most people here can spin up two VMs in two different colos, and setup IRC servers or whatever.
99.99% uptime means it can be down for a few minutes a month, so all it needs to do is fail over properly. In practice, it will probably have many more than 4 9’s.
I think the real reason slack does well is ease of client + service setup, the brain-dead UI, lots of feature creep that a few people care about, mobile clients, etc, etc.
I’m not a huge fan, but it could be worse. At least they didn’t leak everyone’s password like hipchat did.
In most of the world that will buy you a decent mid level developer at least, a great senior or two in many. Even if it's below market, if this was my pet OSS project I'd happily take a pay cut to get more job satisfaction.
I really didn't expect my post to be so controversial, is the HN crowd really so terrified about running there own hardware?