Look up a status, pick the right one for an API, or hit a live endpoint that actually returns it. Add ?code=418 to this URL and the response is that status — useful for curl, interceptors, and “what does my client do on 503?” Nothing here phones home except the Try it fetch to this same page.
Which class?
The server cannot process the request because it is malformed or semantically invalid at the HTTP layer.
When to use
Broken JSON, missing required headers, invalid types. The client must change the request.
Don’t
Auth failures are 401/403. “Looks like JSON but the fields are wrong” is often 422.
Live URL
curl -i https://corecoding.com/utilities/http-status.php?code=400
No codes match.
Code use cases