rel="preconnect"

The preconnect keyword for the rel attribute of the {{HTMLElement("link")}}  element is a hint to browsers that the user is likely to need resources from the target resource’s origin, and therefore the browser can likely improve the user experience by preemptively initiating a connection to that origin. Preconnecting speeds up future loads from a given origin by preemptively performing part or all of the handshake (DNS+TCP for HTTP, and DNS+TCP+TLS for HTTPS origins).

<link rel="preconnect"> will provide a benefit to any future cross-origin HTTP request, navigation or subresource. It has no benefit on same-origin requests because the connection is already open.

If a page needs to make connections to many third-party domains, preconnecting them all can be counterproductive. The <link rel="preconnect"> hint is best used for only the most critical connections. For the others, just use <link rel="dns-prefetch"> to save time on the first step — the DNS lookup.

Examples

<link rel="preconnect" href="https://example.com" />

You can also implement preconnect as an HTTP Link header, for example:

Link: <https://example.com>; rel="preconnect"

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Speculative loading for a comparison of <link rel="preconnect"> and other similar performance improvement features.