Trying again: A survey of quite a few very nice alternatives to Slack and Hipchat. Frankly, using a proprietary chat is just silly nowadays. There's no reason to hand your community/company's tacit knowledge to a 3rd party to hold hostage on their terms (which is what the proprietary options are effectively doing). https://www.how2shout.com/tools/open-source-team-chat-software.html Other reasons why using proprietary chat like Slack is a bad idea: https://davelane.nz/why-slack-better-and-why-open-communities-shouldnt-use-it
@lightweight Slack strictly does not allow on-prem, which makes it unsuitable for orgs that care about security. Now they allow you to supply your own security keys it is a bit better, but I still feel that Slack is one leaky S3 bucket away from disaster.