Usage:

date --set="$(curl -s http://time.d0.ee)"
(or)
date --set="$(wget -O - -q http://time.d0.ee)"

Would result in:

date --set="06 Jun 2025 19:18:07"

Sets time to Europe/Tallinn timezone. Date is only told when this page is requested using 'curl/*' or 'wget/*' user agent.
Service is offered both via HTTP (for reasons - can't use TLS with wrong time/date) and HTTPS

Source: https://gist.github.com/mikroskeem/b05c4cd0707fa25b78f7a34825b908e1