I need to setup a TXT DNS record on duckdns so that I can verify this domain for Google Search Console. These are my notes so I remember how to do it if I need to do this again.

Duckdns supports setting TXT records by submitting a request to this address

https://www.duckdns.org/update?domains={domain}.duckdns.org&token={token}&txt={dns_txt}

I just replaced {domain} with my subdomain, {token} with the token on duckdns, {dns_txt} with the TXT value I wanted, and used curl to query the website.