Automatic location detection in Ruby on Rails

Question

A technical and legal question - what's the best rails gem to auto-detect location of a web visitor via e.g. IP? Down to granularity of state.

And is this an illegal privacy breach? Why do some sites auto-detect location and others ask for manual zip code input?

Thanks in advance!

Answer 1

You'll need some sort of IP-to-location translation database, like this one:

http://www.maxmind.com/app/ip-location

[Update: free version is here: http://www.maxmind.com/app/geolitecity]

The reason some auto-detect and others don't is a question of reliability. You can't guarantee the IP you're seeing is the actual end users IP (proxies/VPNs/etc cause problems) so while it's fine for general use, it's not practical if you're doing something for example with billing or calculating shipping costs.