***Update, September 2016 Since Google's privacy politics has changed, you can't use HTML5 Geolocation API if your server doesn't have HTPPS certificate or user doesn't allow you check his location.
So now you can use user's IP and check in in PHP or get HTTPS certificate.
The database format is known as Comma Separated Values (CSV).
We will scan through all new IP address range once reported for its network name and location.
This is a manual process and requires actual usage from any IP address in order for us to determine the related ISP name and location.
Other sources are possible as long as they have the same format: CSV file, fields enclosed with quotes (“) and separated with comma (,), lines ending with LF (\n). DO NOT EVER USE VALUES THAT YOUR USERS CAN INFLUENCE! If you let users supply arguments to Subselect(), you are letting them to do whatever they like with your database!
Ideally I'm trying to put together a PHP script that I can query from any web browser and it returns the country of the IP address that accessed the PHP script. Which one looks the most trustworthy is up to you :) Otherwise, there are scripts which are based on local databases on your server.
The database data needs to be updated regularly, though. Edit: And of course, depending on your project you might want to look at HTML5 Location features.
You can't use them yet on the Internet Explorer (IE9 will support it, long way to go yet), but in case your audience is mainly on mobile devices or using Safari/Firefox it's definitely worth to look at it!
You can get the complete accuracy and coverage from data accuracy report page.
We are monitoring all new IP address range assigned.
IP2Location is also available in binary format which works together with the IP2Location API in several programming languages.
You will receive your login and password through email immediately after payment is authorized.
Our database is updated monthly to make sure it is always accurate. The inaccuracy is due to the dynamic IP address allocation by large ISPs such as AOL, MSN TV and other proxies.