HTTP 418 I'm a Teapot
The server refuses to brew coffee because it is a teapot (April Fools' joke).
4xx Client Error
418
I'm a Teapot
Description
The 418 I'm a Teapot status code was defined in RFC 2324, Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0), as an April Fools' joke in 1998. It indicates that the server refuses to brew coffee because it is, permanently, a teapot. A combined coffee/tea pot that is temporarily out of coffee should instead return 503 (Service Unavailable). The body of the response may be short and stout. Despite being an April Fools' joke, this status code has been adopted by many real-world applications as an Easter egg, and has been implemented in various frameworks and libraries. The IETF has confirmed that this status code is not expected to be implemented by actual HTTP servers.
When Is It Used?
Used humorously as an Easter egg in APIs and web applications. Some developers use it to indicate that the server will not process a request that it considers absurd or outside its intended purpose. Google famously implements it at google.com/teapot.
Example Response
HTTP/1.1 418 I'm a Teapot
Content-Type: text/plain
I'm a teapot, short and stout.
Here is my handle, here is my spout.