431 Request Header Fields Too Large

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?

431

Request Header Fields Too Large

Client error · RFC 6585

Headers as a whole, or one header, are too large.

When to use

Giant cookies, oversized Authorization tokens.

Don’t

Body too large is 413. nginx often uses unofficial 494 instead.

Live URL

curl -i https://corecoding.com/utilities/http-status.php?code=431


    

Code use cases