From the 1998 April Fools' hypertext coffee-pot spec. It is a real, registered code, and a teapot cannot brew coffee.
Genuinely useful as a canary: pick a code nothing in your stack handles specially, and assert it survives your client, your proxy and your logging untouched.
1 endpoint in this playground answers with 418. Every one is free, needs no signup, and can be called from the browser or with curl.
GET https://funapi.dev/api/coffee/v1/teapot — Always. It is, in fact, a teapot. (Coffee Shop API)All HTTP status codes · All 37 mock REST APIs · Getting started guide