I've been abusing HTTP Status Codes in my APIs for years
> Returning a 2xx code immediately tells the client that the HTTP response contains a payload that they can parse to determine the outcome of the business/domain request.There is nothing in the protocol that mandates only 2xx status codes are parsable. Instead, the Content-Type pinpoints to the client what kind of content the body has, regardless the status code. And the content-type will most probably be what the client asked (if not, then the server announces that the response content is not subject to negotiation, something that you see rarely nowadays..)In general I think this post reflects one of the mentalities that appeared around 10 years ago regarding HTTP APIs (another was the extreme hypermedia-driven APIs). But I really think nowadays we can do much better, we can deliver a practical API that works 99% of the times.By the way in the latest HTTP RFC (RFC9110) status code 422 is finally officially defined (previously was part of webdav extention), which means that the war 422 vs 400 for validation and other semantic errors is over and we have a clear winner. But 200 vs 404 for something that was not found? Well that was has ended long ago I think..