Safari added support for HTTP/3 in version 14, released in September 2020. That’s why it isn’t listed as an experimental feature any more. https://developer.ap

Safari added support for HTTP/3 in version 14, released in September 2020. That’s why it isn’t listed as an experimental feature any more. https://developer.apple.com/documentation/safari-release-notes/safari-14-release-notes https://developer.apple.com/documentation/safari-release-not... You can check with Cloudflare’s test page here: https://cloudflare-quic.com https://cloudflare-quic.com Alternatively, open up developer tools, go to the network panel, right-click on the headings and enable the protocol field. It will tell you which protocol was used for each request made by your browser. Obviously the server also needs to support HTTP/3 for a request to use HTTP/3.