Glossary · Performance

Early Hints (103)

HTTP 103 Early Hints is an informational response that lets a server send Link headers before the final response so browsers can preload resources sooner.

Updated October 6, 2026

Early Hints is the HTTP status code 103. A server sends it before the final response, carrying Link headers that point to resources such as stylesheets, fonts or origins the page will need. The browser starts fetching them while the server is still preparing the HTML.

Why it matters

Servers often spend 100 to 500 ms generating a page, for instance querying a database. During that time the connection sits idle. With Early Hints the browser uses that gap to preload critical CSS or preconnect to a CDN, which can improve LCP and FCP. Support exists in major browsers over HTTP/2 and HTTP/3, and CDNs such as Cloudflare can send hints based on previous responses.

Example

HTTP/2 103
link: </app.css>; rel=preload; as=style
link: <https://cdn.example.com>; rel=preconnect

HTTP/2 200
content-type: text/html
...

The 103 response comes first, and the 200 follows once the page is ready.

Common misconceptions

  • It replaces server push. Push sends the resource itself, while hints only tell the browser what to request.
  • Every client supports it. Unsupported clients simply ignore it.
  • More hints are better. Hinting the wrong files wastes bandwidth.

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