What services can I used to find a user's location based on their IP address?

Question

If you need to locate a user based on their IP address, what services are available (free and not free services are fine)?

P.S. I understand that some users use proxies etc., that means the result is not 100% accurate. That's ok.

Answer 1

Most geolocation services allow you to download a database full of IP Address to city or country maps. Some also provide web service apis for free (limited number of requests) or a paid subscription.

MaxMind has one such service that you can use which is free to determine the user's location. Their minFraud service allows 500 free queries per day.

A sample for their web service in ASP

Dim objHttp, strQuery
strQuery = "http://geoip1.maxmind.com/a?l=" & license_key & _
    "&i=" & ipaddress
set objHttp = Server.CreateObject("Msxml2.ServerXMLHTTP")
objHttp.open "GET", strQuery, false
objHttp.send
Response.Write objHttp.ResponseText
Set objHttp = Nothing

They also offer APIs for determing credit card fraud probability based on location, card number, etc, in their paid version.

Another service is ip2location. ^{John Millikin}

Also, IPLigence offers 50 free queries a day.

For .NET Coders, there is the IPAdressExtensions module (open source, free and no web service required) ^purekrome

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More info about geolocation is available on wikipedia.