HTTP 103 Early Hints is an informational response that allows the server to send preliminary headers before the final response, primarily used to let the browser start preloading resources (CSS, JS, fonts) while the server is still generating the full response. Defined in RFC 8297, it enables servers to send Link headers with rel=preload or rel=preconnect hints, shaving hundreds of milliseconds off page load times by parallelizing resource fetching with server-side processing.
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/103
Example request:
curl -i "https://httpstatus.com/api/status/103"