Firefox Canary domain. If it returns an IP, DoH will be used

use-application-dns.net

Public list of DoH servers.

Official documentation Interactive web page here. Add -v for verbose mode.

curl -H "accept: application/dns-json" "https://dns.google/resolve?name=www.google.com&type=A"

Note: There is also a human-friendly web interface at https://dns.google/. This web app displays JSON results in a browser but does not implement an API; do not confuse its https://dns.google/query? URLs with the two API URLs.

Add -v for verbose mode.

curl -H "accept: application/dns-json" "https://cloudflare-dns.com/dns-query?name=www.google.com&type=A"

Following RFC, the endpoint should receive a base64 encoded HTTP friendly DNS packed.

https://f49a8d75-ebec-442d-9204-52992759684a.doh.threatdefense.infoblox.com/dns-query?dns=AAABAAABAAAAAAAAA3d3dwdleGFtcGxlA2NvbQAAAQAB