Intent to Prototype: WebSockets over HTTP/3

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Momoka Yamamoto

Nov 16, 2022, 11:16:20 AM11/16/22
to, Adam Rice, Nidhi Jaju, Daisuke Enomoto

Contact emails





Implement support for WebSockets over HTTP/3 in Chromium according to specification RFC9220 . This would only be used for secure WebSockets requests, and only if there is already an HTTP/3 connection where the server has already advertised support for WebSockets over HTTP/3 via the HTTP/3 SETTINGS parameter defined in the specification

Blink component



Speed is the major motivation for this change. The number of connections to web servers over HTTP/3 is significantly increasing, but without WebSockets being supported over HTTP/3, it currently takes a few RTTs to negotiate a new connection. Supporting WebSockets over HTTP/3 would significantly cut down on latency. It also reduces the resource usage of the server implementing WebSockets, and so encourages adoption of WebSockets to the ecosystem.

Initial public proposal

TAG review

TAG review status

Not applicable


Interoperability and Compatibility

Gecko: No signal

WebKit: No signal

Web developers: No signals

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?


Is this feature fully tested by web-platform-tests?


Flag name

Requires code in //chrome?


Tracking bug

Launch bug

Estimated milestones

No milestones specified

Link to entry on the Chrome Platform Status

This intent message was generated by Chrome Platform Status.

Rick Byers

Nov 16, 2022, 3:23:10 PM11/16/22
to Momoka Yamamoto,, Adam Rice, Nidhi Jaju, Daisuke Enomoto
Sounds cool, thanks for the heads up and good luck!

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