Possibly because running a bot client is much different from running a webserver. Dialing outbound to connect to slack is much easier than figuring out or configuring your own canonical URL, opening ports, etc.<p>On the other hand, preparing hands as a single image seems a bad way of doing this; Does the slack API only allow a single image per conversation? I agree with your preparation microservice idea - There should be (and probably are several) a service that allows you to specify a poker hand as a query string and get back an image of the hand. More simply, though: A webfont and <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Playing_cards_in_Unicode" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Playing_cards_in_Unicode</a>