# 103 Early Hints > https://http-status.org/docs/103 **Family:** 1xx Informational ## Rationale Interim response: the server sends preload or connection hints before the final response is ready. ## In Plain Terms The server is giving the browser a head start: 'You’ll probably need these files, so start getting them while I finish the real response.' ## Description The HTTP 103 Early Hints status code is an interim response that lets a server send likely useful response headers, especially Link hints, before the final response is ready. ## Server Perspective ### Usage - Return 103 to advertise critical preload or preconnect work early - Use it only for hints that remain sensible even before the final response arrives - Use it as a performance optimization, not as part of the application's success or error contract - Sending Link preload or preconnect hints before the final HTML response is ready - Helping browsers start fetching critical assets earlier - Reducing page load time when the server already knows which subresources will be needed ### Implementation - Send the early hint headers first, then follow with the normal final response - Hint only headers the client can safely evaluate speculatively, and keep them broadly consistent with the eventual representation - You may send multiple 103 responses as new hints become available before the final response, but most browsers only process the first one; additional 103 responses are ignored by browser clients ### Common Headers - Link is the common choice for preload or preconnect hints; only send other headers when clients can safely treat them as speculative hints rather than final-response metadata. ### Body - Do not include a response body in a 103 response. ### Pitfalls - Do not expose sensitive or misleading hints before the final response is known - Do not overuse preloads that waste bandwidth or contention on the client - Do not rely on 103 to carry semantics that must affect how the client interprets the final response - Do not send 103 responses over HTTP/1.1 unless every client and intermediary in the chain is verified to handle informational responses correctly; RFC 8297 recommends using HTTP/2 or later for Early Hints - Do not send hints when the request may result in a cross-origin redirect; clients must discard 103 hints received before a cross-origin redirect, wasting any preload work already started - As a replacement for the final response - When the hinted resources are speculative enough to waste bandwidth - For application semantics that depend on the final status code or full response body ## Client Perspective ### Pitfalls - Do not treat 103 as a successful final response - Early-hint processing must not affect how the final response is processed beyond safe performance optimizations - Do not assume headers missing from 103 are absent from the final response ## Examples ### HTML page with critical stylesheet The browser can start fetching the stylesheet before the server finishes rendering the page. **Request:** ``` GET https://api.example.test/dashboard ``` **Response:** ``` 103 Early Hints Link: ; rel=preload; as=style 200 OK Content-Type: text/html; charset=utf-8 Dashboard ``` ## Related Codes - [100 Continue](/docs/100.md) - [200 OK](/docs/200.md) - [304 Not Modified](/docs/304.md)