ErrorFindly
1031xx InformationalInfo

HTTP 103 Early Hints

Defined in RFC 8297

What Does HTTP 103 Mean?

The server is sending preliminary headers to allow the client to start preloading resources while the server prepares the full response.

Common Causes

  1. 1Server sending Link headers early for resource preloading
  2. 2CDN or reverse proxy providing early hints
  3. 3Performance optimization for critical resource loading

Impact

  • ⚠Pages may load faster due to early resource preloading
  • ⚠No visible difference other than improved performance

Developer Fix

For web developers and application engineers

  1. 1Add Link rel=preload headers for critical CSS/JS
  2. 2Configure server to send 103 Early Hints
  3. 3Test browser support for Early Hints

Server Admin Fix

For system administrators and DevOps engineers

  1. 1Enable Early Hints in server configuration
  2. 2Configure CDN to support 103 responses
  3. 3Identify critical resources that benefit from preloading

Frequently Asked Questions

Which browsers support 103 Early Hints?
Chrome 103+ and other Chromium-based browsers support Early Hints. Firefox has experimental support. Safari support is in progress. Check caniuse.com for the latest compatibility.
How much can Early Hints improve performance?
Early Hints can reduce page load times by 100-500ms by allowing browsers to start fetching critical resources while the server is still generating the response.

Related HTTP Status Codes

200OK100Continue

About the Author

Web Infrastructure Team

Verified against official RFC specifications and real-world server configurations. HTTP status code behavior confirmed across Apache, Nginx, and Cloudflare.