RFC 2324
HTCPCP/1.0
Larry Masinter, 1 April 1998. The BREW and WHEN methods, the Accept-Additions header, and 418 I'm a teapot.
Read it, annotatedHyper Text Coffee Pot Control Protocol
An April Fools' protocol from 1998 for controlling coffee pots over HTTP, and its 2014 extension for tea. Both run, more faithfully than anyone asked for, on a real teapot and a real coffee pot at http418.nl.
The specifications
RFC 7168
HTCPCP-TEA
Imran Nazar, 1 April 2014. Tea varieties, sugar, 300 Multiple Choices, and the media type message/teapot.
Read it, annotatedTry it
Both pots answer real HTTP. A teapot, asked for coffee:
curl -I https://http418.nl/coffee
HTTP/2 418
A coffee pot, asked properly:
curl -X BREW -H "Accept-Additions: Whole-milk" coffee.http418.nl
Or build a request step by step in the playground.
Compliance
How much of the two RFCs the pots implement. The gaps are honest, and on the to-do list.
| Feature | Section | Teapot | Coffee pot |
|---|---|---|---|
| BREW method, POST as an equivalent | 2324 §2.1.1 | Yes | Yes |
| GET | 2324 §2.1.2 | Yes | Yes |
| PROPFIND | 2324 §2.1.3 | 405, by design | 207 |
| WHEN | 2324 §2.1.4 | No milk, no WHEN | Yes |
| Safe response header | 2324 §2.2.1.1 | No | No |
| Accept-Additions, 406 with the list | 2324 §2.2.2.1 | Yes | Yes |
| No decaf | 2324 §2.2.3 | Not applicable | 406 |
| 418 I'm a teapot | 2324 §2.3.2 | Yes | It's a coffee pot |
| coffee: URI schemes in 28 languages | 2324 §3 | Not applicable | As paths |
| Pot designators, pot-0 and pot-1 | 2324 §3 | One pot | Yes |
| message/coffeepot only | 2324 §4 | Not applicable | 415 otherwise |
| Clock synchronised with NTP | 2324 §5.1 | Yes | Yes |
| BREW to "/" gives 300 and Alternates | 7168 §2.1.1 | In the playground | Not applicable |
| Variety URIs, stop at lesser strength | 7168 §2.1.2 | Yes | Not applicable |
| Sugar, xylitol and stevia | 7168 §2.2.1 | No | Not applicable |
| 403 for additions against consensus | 7168 §2.3.2 | No | Not applicable |
| 418 or 503 for coffee | 7168 §2.3.3 | 418 | 503 on pot-1 |
| message/teapot | 7168 §3 | Yes | Not applicable |
Errata and oddities
- Section 2.1.1 says commands use the media type
application/coffee-pot-command, section 4 saysmessage/coffeepot. A verified erratum, EID 682, sides with section 4. - The Accept-Additions grammar refers to an
addition-rangethat is never defined, and defines anaddition-typethat is never used. - Sweeteners and spices are additions in the grammar, but the RFC never says what they are.
- Section 3 promises the word for coffee in 29 languages and covers 28. Its Catalan, French and Galician
caf%C3%E8is not valid UTF-8, and the Czechk%C3%A1vais missing its closing quote. - "Espressoly", in section 1, is not a typo.
A short history
- 1991At the University of Cambridge Computer Laboratory, researchers point a camera at the coffee pot outside the Trojan Room, so they can see from their desks whether there is any coffee left.
- November 1993The coffee pot goes on the web, and becomes one of the first webcams.
- 1 April 1998Larry Masinter publishes RFC 2324. It cites the Cambridge pot as prior art.
- 22 August 2001The Trojan Room camera is switched off. The pot is sold on eBay to Spiegel Online for £3,350.
- 1 April 2014Imran Nazar publishes RFC 7168, finally giving teapots something to do besides refuse.
- August 2017The chair of the IETF HTTP working group asks Node.js, Go and others to drop 418. Developers protest, the Save 418 Movement is born, and every project keeps the code.
- June 2022RFC 9110, the HTTP semantics standard, lists 418 as reserved, so no real status code can ever take the number.