I don’t think there would be any cause for Slack to complain for at least paid accounts. I glanced through the relevant terms, and there’s really only one even

I don’t think there would be any cause for Slack to complain for at least paid accounts. I glanced through the relevant terms, and there’s really only one even vaguely relevant topic, largely around competing with Slack. In their App Developer Policy <https://api.slack.com/developer-policy https://api.slack.com/developer-policy>: > As part of good business practices, Applications and developers are prohibited from: Circumventing Slack’s intended limitations (including pricing, features and access structures). You may not use the Slack API to replicate or compete with core products or services offered by Slack And in their API Terms of Service <https://slack.com/intl/en-au/terms-of-service/api https://slack.com/intl/en-au/terms-of-service/api>, which cites the app developer policy and then adds: > Further, you will not: … (C) access our APIs or documentation in order to replicate or compete with the Services If Slack spell out that there being no public mirror is an intended limitation, or if they offer a direct equivalent, then they could complain. And they could do for free accounts, which have a history limit that this would incidentally circumvent. But for paid accounts I don’t believe either of these are true, so if it were limited to working with paid accounts I’d say you’d be in the clear with Slack for now. Of course, you’re still subject to their caprice in changing their rules, implementing new features, or just booting you off their platform even without cause at their whim, and that’s a significant existential risk for building such a business. But I don’t think Slack would be particularly likely to boot them off, given that any hostile action on their part would be akin to claiming some degree of ownership of the data. The data belongs to the customer, and they should be able to do whatever they want with it without hindrance. Of course, such reasoning as this is only reasoning. If they did cut off such API access, they’d hardly be the first large company to shut the portcullis to support their own interests against their customers’; Twitter, for example.