For ridiculously easy things like this, I think it's smarter for you to just host it yourself. This way you are not forcing other people to carry your burden.

nginx config example:

  location /ip {
    add_header Content-Type "application/json";
    return 200 '{"host":"$server_name","ip":"$remote_addr","port":"$remote_port","server_ip":"$server_addr","server_port":"$server_port

"}\n'; }

Which will return something like this in JSON format:

    {"host":"www.example.org","ip":"199.200.200.14","port":"7990","server_ip":"199.200.100.229","server_port":"443"}

This is all done 100% within NGINX, and I include a lot of stuff you probably don't want or care about. Other web servers probably have similar capabilities.