For APIs, Checks tend to be a bit urgent. If the API check fails, I know something is wrong, and needs investigating immediately.
I have OnlineOrNot check its own API every minute:
To make OnlineOrNot actually check the API correctly, I have OnlineOrNot make an API request as a real (test) user, with a valid GraphQL query.
I set the following HTTP request settings:
As GraphQL APIs can return 200 OK even when things are going horribly wrong, it's important to set assertions to check the data you queried is coming back correctly:
Finally, in advanced settings, I set the check to monitor from a location close to my database (for fastest results), and set it to only alert me if two checks in a row fail.
As I'm already checking the response via Assertions, I don't set 'Text to search for' for my API check.
As I check my phone (way too much), I find email notifications to work quite well when things go wrong (no additional settings required).
For added redundancy though, I also have alerts sent to Slack and Discord, which I've added as integrations for my account: