HTTP 411 Length Required indicates the server requires the Content-Length header to be present in the request. The server refuses to accept the request without a defined content length, typically because it needs to allocate resources or enforce size limits before receiving the body. This is increasingly rare as chunked transfer encoding (Transfer-Encoding: chunked) allows streaming without knowing the total size upfront.
Response includes the status code, standard headers (including Content-Type), and a small diagnostic JSON body describing the request and returned status.
Simulator URL (copy in the app after load — not a normal link):
https://httpstatus.com/api/status/411
Example request:
curl -i "https://httpstatus.com/api/status/411"