Geo Location API and finding user within a radius

Question

I have a Java application and I would like to find out the location of a visitor. The API would give me a the zip code of visitor and then based on that zip code, I will fin

Answer 1

I don't know how accurate it is, but have you looked at IPinfoDB? They'll return XML and JSON results but you'll need to register for an API key. It doesn't provide anything for a radius though, but for nearby zipcodes, you can use something like this: http://www.geonames.org/export/web-services.html#findNearbyPostalCodes