Link
The HTTP Link entity header field provides a means for serializing one or more links in HTTP headers. This header has the same semantics as the HTML <link> element. The benefit of using the Link header is that the browser can start preconnecting or preloading resources before the HTML itself is fetched and processed.
In practice, most link types don't have an effect in the HTTP header. For example, the icon relation only works in HTML, and stylesheet does not work reliably across browsers (only in Firefox). The only relations that work reliably are preconnect and preload, which can be combined with 103 Early Hints.
Syntax
Link: <uri-reference>; param1=value1; param2="value2"
<uri-reference>-
The URI reference, must be enclosed between
<and>and URL encoded.
Parameters
The link header contains parameters, which are separated with ; and are equivalent to attributes of the <link> element.
Examples
The URI (absolute or relative) must be enclosed between < and >:
Link: <https://example.com>; rel="preconnect"
Link: https://bad.example; rel="preconnect"
Encoding URLs
The URI (absolute or relative) must encode char codes greater than 255:
Link: <https://example.com/%E8%8B%97%E6%9D%A1>; rel="preconnect"
Link: <https://example.com/苗条>; rel="preconnect"
Specifying multiple links
You can specify multiple links separated by commas, for example:
Link: <https://one.example.com>; rel="preconnect", <https://two.example.com>; rel="preconnect", <https://three.example.com>; rel="preconnect"
Specifications
| Specification |
|---|
| Web Linking # header |
Browser compatibility
BCD tables only load in the browser