1xx Informational
103 Early Hints
Preliminary headers sent before the final response so the browser can start preloading resources.
Typically carries Link: <…>; rel=preload headers while the server is still generating the page, improving load time.
Notes
- Supported by Chromium browsers and CDNs such as Cloudflare. Clients that do not understand it simply ignore it.
Example response
HTTP/1.1 103 Early Hints
Link: </style.css>; rel=preload; as=style
Date: Thu, 22 Oct 2026 08:00:00 GMT Check a URL’s status with curl -I https://example.com, which prints the status line and headers.