rel="compression-dictionary" HTML attribute value

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The compression-dictionary keyword for the rel attribute of the <link> element is a link that browsers can use to download a compression dictionary that can be used to compress future downloads for resources on this site so the download sizes of those resources are smaller than standard compression.

Note: if the website has a Content-Security-Policy header, the connect-src directive (or default-src, if connect-src is not set) must permit the location of the dictionary resource to avoid the request being blocked.

See the Compression Dictionary Transport guide for more information.

Specifications

Specification
Compression Dictionary Transport
# name-link-relation-registration

Browser compatibility

desktop mobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
rel=compression-dictionary
Experimental
Chrome – Full support
Chrome 130 (Release date: 2024-10-15)
footnote Full support
Edge – Full support
Edge 130 (Release date: 2024-10-17)
footnote Full support
Firefox – No support
Firefox
footnote
footnote See bug 1918013
Opera – Full support
Opera 115 (Release date: 2024-11-27)
footnote Full support
Safari – No support
Safari
footnote No support
Chrome Android – Full support
Chrome Android 130 (Release date: 2024-10-15)
footnote Full support
Firefox for Android – No support
Firefox for Android
footnote
footnote See bug 1918013
Opera Android – Full support
Opera Android 86 (Release date: 2024-12-02)
footnote Full support
Safari on iOS – No support
Safari on iOS
footnote No support
Samsung Internet – Full support
Samsung Internet 28 (Release date: 2025-04-02)
footnote Full support
WebView Android – Full support
WebView Android 130 (Release date: 2024-10-15)
footnote Full support
WebView on iOS – No support
WebView on iOS
footnote No support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support
No support
No support
Experimental. Expect behavior to change in the future.
See implementation notes.

See also