HTTP Status Code 103 = “Early Hints”
It is an informational HTTP response used to improve website loading performance.
Purpose
A server sends 103 Early Hints before the final response (200 OK) to tell the browser:
“Start loading these resources now.”
This helps preload:
- CSS files
- Fonts
- JavaScript
- Images
and can speed up page rendering.
Example
http id=”jlwm4a”
HTTP/1.1 103 Early Hints
Link: ; rel=preload; as=style
HTTP/1.1 200 OK
Content-Type: text/html
The browser begins downloading style.css before the full page arrives.
Common use cases
- Faster website performance
- CDN optimization
- HTTP/2 and HTTP/3 performance improvements
- Server-side rendering frameworks
Frameworks/CDNs that may use it:
- Cloudflare
- Fastly
- Vercel Is 103 an error?
No.103 is not an error status. It is an informational response in the 1xx category.
Categories:
1xx→ Informational2xx→ Success3xx→ Redirects4xx→ Client errors5xx→ Server errors Example in Node.js
js id=”4ebmij”
res.writeEarlyHints({
“link”: “; rel=preload; as=style”
});
Browser support
Modern browsers like:
- Google Chrome
- Mozilla Firefox
- Safari
support Early Hints to varying degrees.
More info:
MDN 103 Early Hints documentation