ifconfig
One primary service, no API keys needed.
Get IP address of your server:
curl ifconfig.me
Get User-Agent:
curl ifconfig.me/ua
Get lang/language:
curl ifconfig.me/lang
Get encoding:
curl ifconfig.me/encoding
Get mime:
curl ifconfig.me/mime
Get charset:
curl ifconfig.me/charset
Get forwarded IPs:
curl ifconfig.me/forwarded
Get all headers (text/plain):
curl ifconfig.me/all
Get all headers (json):
curl ifconfig.me/all.json