103 Early Hints
1xx Informational
RFC 8297
A heads-up before the real response — start preloading now.
What 103 Early Hints means {#what}
Sent before the final response to let the browser start fetching linked resources (CSS, fonts, scripts) while the server is still preparing the actual response. A performance optimization that cuts perceived load time, used with the Link header.
When you’ll see a 103 {#when}
- CDNs and servers optimized for Core Web Vitals
- Pages that benefit from early resource hints
When to use 103 {#use}
- Include
Linkheaders pointing to critical CSS or JS that will be needed regardless of the final response