HTTP/2 Server Push Headers Builder

HTTP/2 server push lets a server proactively send resources (CSS, JS, fonts, images) to the client before the browser even requests them. This eliminates a full round-trip for critical assets that the server knows the browser will need.

The Link preload header instructs the browser (and HTTP/2 intermediaries) to begin fetching the resource immediately. Format: </path/to/resource>; rel=preload; as=<type>. The 'as' attribute tells the browser what kind of resource it is so it can apply the correct content security policy and cache behavior.

Set crossorigin=anonymous for fonts and resources fetched with CORS (cross-origin). If the resource requires credentials, use crossorigin=use-credentials. For same-origin resources like scripts and stylesheets loaded from your own domain, you typically don't need crossorigin.

No. Server push is an HTTP/2-only feature. With HTTP/1.1, the Link preload header still tells the browser to preload the resource eagerly, but no push occurs — the browser will make a normal request for it.

In your nginx location block, add: add_header Link "</style.css>; rel=preload; as=style"; You can combine multiple resources in one header value by separating them with commas. This tool generates the complete nginx directive for you.

Server push reduces time-to-interactive for critical resources by eliminating the browser's discovery phase. However, over-pushing can waste bandwidth if the browser already has the resource cached. Consider using Cache-Digest headers or limiting push to first-visit critical path resources only.