10c per slack API call. I could make a mobile phone call for less than that in 1995. It is expensive...
IFTTT, Zapier, NodeRed, etc. are your competitors.
E.g.
https://ifttt.com/applets/J75VtBA9-get-an-email-when-a-webho... -> https://ifttt.com/applets/KWqQedih-make-a-web-request-when-i.... They have lots of AI things too.
The problem is you are saying "API" call so you are already dealing with devs. They can save $10k by writing their own Slack integration (even easier if they pay IFTTT $150/y), and the enterprises will want you to be all FedRAMP, ISO, SOC, Data Resident etc.