coderef

Compression Dictionary TransportLimited availability

Compression Dictionary Transport is a mechanism for using designated HTTP responses as an external dictionary for future HTTP responses for compression schemes that support using external dictionaries (e.g., Brotli and Zstandard)

Not yet supported in all major browsers — check the table and provide a fallback.

How to use ↓Compare browsers

Browser support

DesktopChrome
1–129Not supported
130+Supportedsince Oct 15, 2024
Current: 155
Edge
12–129Not supported
130+Supportedsince Oct 17, 2024
Current: 154
Firefox
✕Not supportedup to 157
Current: 157
Safari
✕Not supportedup to 27
Current: 27
MobileChrome Android
18–129Not supported
130+Supportedsince Oct 15, 2024
Current: 155
Firefox Android
✕Not supportedup to 157
Current: 157
Safari iOS
✕Not supportedup to 27
Current: 27

How to use

Not supported in Firefox, Safari, Firefox Android, Safari iOS. Use feature detection below and provide a fallback (or a polyfill) for those browsers.

Example

Full syntax and examples are on MDN: rel#compression-dictionary.

Feature detection

JS · check before using
if ("rel" in document.createElement("link")) {
  // the rel attribute/property of <link> is supported
}

Documentation (MDN)

Specification

Sub-features

Support for each part of the feature (8). The overall table above shows when the whole feature works.

Sub-featureChromeEdgeFirefoxSafariChrome AndroidFirefox AndroidSafari iOS
link.rel.compression-dictionary130130✕✕130✕✕
http.headers.Accept-Encoding.dcb130130✕✕130✕✕
http.headers.Accept-Encoding.dcz130130✕✕130✕✕
http.headers.Available-Dictionary130130✕✕130✕✕
http.headers.Content-Encoding.dcb130130✕✕130✕✕
http.headers.Content-Encoding.dcz130130✕✕130✕✕
http.headers.Dictionary-ID130130✕✕130✕✕
http.headers.Use-As-Dictionary130130✕✕130✕✕