The teapot status code: where it came from and why it is still reserved
Runs in your browser. Nothing you type is sent anywhere. Updated on 25 Oct 2026.HTTP 418 comes from the Hyper Text Coffee Pot Control Protocol, an April Fools' joke published as RFC 2324 in 1998: the machine you asked to brew coffee replies that it is a teapot. A 2017 proposal to free the number for real use was withdrawn after public objection, so 418 stays permanently reserved and permanently unusable. Node, Go and Python all still carry a constant for it.
Open the page with 418 I'm a Teapot already selected.
Read the meaning: a joke from the Hyper Text Coffee Pot Control Protocol, under Defined by as RFC 2324 of 1998.
Read "When to use it" and the note on why the code stays reserved and never belongs in a real API.
Press Copy summary to take its meaning, its use and the RFC as plain text.
This HTTP status codes reference lists every registered code from 100 to 511, plus the unregistered ones that nginx, Apache, Laravel and Cloudflare return. Each entry says what the code actually means, when to send it, whether a cache may store the response without cache headers, whether a redirect changes the request method, and which RFC defines it.
Search works three ways. Type a number such as 404, or a class such as 4xx, to jump straight to it. Type a name such as "not found". Or describe what you want to express, and the intent search finds the code: "login failed" gives 401, "rate limit" gives 429, "file too large" gives 413, "validation failed" gives 422.
Every common code comes with a copyable snippet for raw HTTP, Express, Fastify, FastAPI, Go and PHP, including the header that code requires, such as WWW-Authenticate on a 401 or Allow on a 405. Nothing is sent anywhere; the whole table is in the page.
The rest of the article, and all 6 questions about HTTP Status Codes, are on the HTTP Status Codes page.
Use 401 Unauthorized. It means the server does not know who you are, so a missing, expired or wrong credential belongs there. Use 403 Forbidden only when you know who the caller is and are still refusing. The specification wants a WWW-Authenticate header on every 401.
RFC 9110 section 15.1 lists 200, 203, 204, 206, 300, 301, 308, 404, 405, 410, 414 and 501 as heuristically cacheable, and RFC 7725 adds 451. A cache may store those with no Cache-Control or Expires header, which is why a temporary 404 can persist. Every other code needs explicit cache headers.
418 I'm a Teapot comes from RFC 2324, an April Fools' joke from 1998 about a coffee pot protocol. A 2017 proposal to reuse the number was withdrawn after objections, so it stays reserved in the IANA registry and must never be used for a real meaning.
No. 499 is an nginx log-only code for a client that hung up, and 520 to 527 are Cloudflare codes for problems between the edge and your origin. None are registered with IANA. They are listed here because you will meet them in logs, each marked with the product that invented it.
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