Anything unexpected returns 503. Try http://codes.io/404/ http://codes.io/404/ (notice the ending /) Besides, 1223 isn't specified by the HTTP RFCs, nor is it

Anything unexpected returns 503. Try http://codes.io/404/ http://codes.io/404/ (notice the ending /) Besides, 1223 isn't specified by the HTTP RFCs, nor is it returned anywhere except from a library call in a buggy library. I'd say it's not appropriate for an HTTP testing service to support 1223.