What is 418 I'm a teapot?

April Fools origins ☕

RFC2324 is a tongue-in-cheek protocol for controlling coffee pots; 418 is part of that joke.

What RFC2324 says

• Published on April 1, 1998 as a joke RFC.
• RFC 2324 §2.3.2 describes trying to brew coffee with a teapot, not asking a coffee pot to brew tea.
• The IANA HTTP status registry lists 418 as (Unused), referencing RFC 9110 §15.5.19. The number is reserved because of its deployment history, not assigned a new general-purpose meaning.

Example response

An educational HTTP/1.1 illustration of the joke response. The ASCII body is 16 bytes with no trailing newline.

HTTP/1.1 418 I'm a teapot
Content-Type: text/plain
Content-Length: 16

Short and stout.

Where you might see it 🧪

You may encounter it in demos, test services, or libraries. Check the particular service and response to understand why it was returned.

Common appearances

• Some web servers return it on special paths (like /teapot) as a hidden joke.
• Test/diagnostic services or libraries sometimes expose a 418 endpoint.
• Docs and blogs cite it as a fun HTTP trivia item.

Caveats

• The teapot meaning is not a general HTTP error definition. Clients that do not recognize the code handle it by its 4xx class.
• Monitoring may label it as unknown depending on its code table. Do not infer success from the label alone.

How to treat it in practice 💡

Keep 418 out of production APIs; stick to standard 4xx/5xx codes.

Recommendations

• Use standard HTTP statuses for errors and validation (400s/500s, not 418).
• Do not assume 418 is harmless. Inspect the URL, response body, and service documentation, and verify whether the intended operation succeeded.
• Distinguish the RFC 2324 joke from the currently reserved code in RFC 9110. For ordinary APIs, select a status with the appropriate meaning.

Specifications

RFC 2324 §2.3.2 / RFC 9110 §15.5.19 / IANA HTTP Status Codes