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.
Easy anti-spam measure which takes it one-step further by blocking potentially bad IP address from using your resources.
Metropolis can solve any Captcha for you. Just pass the Captcha Image and the API will return the text. Plain and Simple.