rel="compression-dictionary"
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.