IP -> Location resolution

[scrupul0us]

is there a free service todo this... all i want is a zipcode

i want to serve my users with their local weather

[MarkR]

Firstly, you are not going to get much better than the country they're in if you're looking for a free database.

Secondly, assuming you pay for one, you're still not going to get that much resolution. IP location is inherently unreliable - ISPs use various proxying / pooling techniques which make the IP address near useless to determine the user's actual location.

Here in the UK, for instance, I know of at least one ISP which allocates users the same IP regardless of where they dial in from- surprisingly, you can also call them (at local rate) from Holland and Germany (and still get the same IP).

Historically when people used local ISPs, it might have worked. Nowadays, it's just a wild guess.

Mark

[bradgrafelman]

What's wrong with asking them for their zipcode and storing it in a cookie?

[scrupul0us]

this is tru brad...

that will have to be my first ajax project for my site... having it load weather without reloading the whole page

[etully]

http://www.maxmind.com/app/city

This site offers $20 for 50,000 queries. (Of course, you should be caching the information so that you don't have to lookup IP ranges that you've seen before. For example, if you lookup 1.2.3.4, you should cache that under 1.2.3 and when 1.2.3.66 comes to your site, you probably don't have to query MaxMind again).

They also offer $370 per month to license the info.

In my experience, the info is better than MarkR suggests - but he's right, it's not perfect. Since this is just for weather, it's probably not important to achieve even 95% accuracy.

And as far as free goes, I've never seen data more specific than which country they're in.