% curl ipinfo.io/ip
curl: (7) Failed to connect to ipinfo.io port 80 after 25 ms: Connection refused
% curl https://ipinfo.io/ip
curl: (7) Failed to connect to ipinfo.io port 443 after 29 ms: Connection refused
They suck and apparently block curl (and lynx and elinks) from dynamic IP, it works in Firefox or on a server with static IP.
Another one is ifconfig.me/ip so
curl https://ifconfig.me/ip
that works.