103 Early Hints
Headers that arrive before the response, so the browser can get a head start.
RFC 8297, from 2017, is the newest piece in the drawer: while the server is still assembling the page, a 103 sends Link headers with rel=preload ahead — and the browser starts fetching the stylesheet and fonts before the final response exists.
Cloudflare and the big CDNs return it; Chrome has acted on it since 2022. Like every 1xx, it is interim: the real response comes later, with its own status and headers — the hints promise nothing.
HTTP/1.1 103 Early Hints
Link: </estilo.css>; rel=preload; as=style
Link: </fontes/serif.woff2>; rel=preload; as=font
HTTP/1.1 200 OK
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