Telize offers a JSON IP and GeoIP REST API allowing to get a visitor IP address and to query location information from any IP address. It outputs JSON-encoded IP geolocation data, and supports both Cross-origin resource sharing (CORS) and JSONP.
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GETLocation with specific IP
GETLegacy - GeoIP
Get IP address in JSON format. Returns the visitor IP address (IPv4 or IPv6) in a JSON object.