Geolocation is one of the most popular subjects for today's web & there are many solutions that help geo-enabling web applications.

YQL Geo Library is an impressive resource for geolocation as it is totally free & JavaScript-based.

It has various powerful features like:

• detecting the visitor’s location with the W3C geo API and with IP as a fallback
• find geo location from text
• find location from lat/lon pair
• find locations in a certain web document (by URL)
• get the location for a certain IP number

The library is lightweight (4kb uncompressed) & non-complicated. It just works by calling a function like:

yqlgeo.get('217.12.14.240',function(o){
  alert(o.place.name + ',' + o.place.country.content +
        ' (' + o.place.centroid.latitude + ',' +
               o.place.centroid.longitude + ')'
        );
});

will get you the city, country, latitude & longitude of any given IP.

IP Location Tools is a free web service that helps you detect the country/city of an IP number.

It can be used in 2 ways:

• with API (no installs required)
• by downloading the geolocation database

Although downloading the SQL database & running it on our own database servers is much more flexible, keep in mind that there are 1.4 million records in it.

The geolocation database is updated regularly (once a month)

IP Location Tools offers another nice service: fraud detection. Again with an API request, with the zip code you submit, system compares the location of the IP and the area where zipcode belongs to. Can be very helpful, specially for e-commerce websites.