Reference

Verify that signed exchanges are working

Make a request with the signed exchange request header:

1. Open a terminal and run the following command, replacing https://example.com with your domain:

curl -svo /dev/null https://example.com -H "Accept: application/signed-exchange;v=b3"

2. Verify that the Content-Type in the response headers is application/signed-exchange;v=b3 rather than text/html.

Certificate authority used with SXGs

Cloudflare uses Google for SXGs' certificate issuance ↗. Once SXGs is enabled, Cloudflare automatically adds the Certification Authority Authorization records on behalf of the zones. Refer to the following example below:

dig example.com caa

;; ANSWER SECTION:
example.com. 3600 IN CAA 0 issue "pki.goog; cansignhttpexchanges=yes"
example.com. 3600 IN CAA 0 issuewild "pki.goog; cansignhttpexchanges=yes"