Is HTTP 103 a client or server error?

103 is an informational code (1xx). It's an intermediate response — the final status will follow.

How is HTTP 103 different from 200 OK?

The request succeeded and the response body contains the requested data. Both codes look similar but signal different situations — see the "Similar Codes" section below for a full comparison.

informational RFC 8297

HTTP 103 Early Hints

Server is sending hints (usually Link: preload headers) before the final response.

What it means

An optimization: the server sends `103 Early Hints` with `Link` headers pointing at critical resources (CSS, fonts, JS) before it finishes generating the actual response. The browser can start preloading those assets while the server is still building the HTML. Cloudflare, Fastly, and Chrome all support it. Real-world LCP improvements of 200-400ms have been measured.

When servers send it

•Server-side rendering framework wants to hint at critical resources
•CDN edge (Cloudflare Early Hints) knows which resources this page usually loads

What the client does

Starts fetching the resources listed in `Link: ; rel=preload` headers. Waits for the final response as normal.

Example response

HTTP/1.1 103 Early Hints
Link: </styles.css>; rel=preload; as=style
Link: </app.js>; rel=preload; as=script

When you see it

•Modern Next.js / Astro / Remix apps opting into early hints
•Cloudflare "Early Hints" feature enabled on the zone

Similar codes

200 OK success

The request succeeded and the response body contains the requested data.

100 Continue informational

Server received the request headers and the client should proceed with the request body.

101 Switching Protocols informational

Server is switching to a different protocol (usually WebSockets or HTTP/2).

← All HTTP status codes · HTTP status cheat sheet · HTTP headers reference