javascript - What's the API Key for in Google Maps API V3?

Question

In the older version of the API, I'd have to insert the javascript into the page using something like this for just basic functionality to work:

http://maps.google.com/maps?file=api&v=2&key=GoogleMapsAPIKey

Where I had to configure the API key for each individual site. Looking at the documentation, it says to get a basic map working I just need this:

http://maps.google.com/maps/api/js?sensor=true/false

Where does the API key fit in? Do I need to worry about it if I just plan on using a basic map and marker and none of the more advanced functions?

I'm also testing on localhost, but the FAQ says I still need to register a key for it, which I haven't done and it still works.

Answer 1

Whilst it is true that V3 of the Google Maps API does not require an API key, it is there for a reason. Google recently introduced the following usage limits:

Web sites and applications using each of the Maps API may at no cost generate:

• up to 25,000 map loads per day for each API
• up to 2,500 map loads per day that have been modified using the Styled Maps feature

In order to monitor usage an API key is necessary, as the developer notes make clear:

All Maps API applications should load the Maps API using an API key. Using an API key enables you to monitor your application's Maps API usage, and ensures that Google can contact you about your application if necessary. If your application's Maps API usage by exceeds the Usage Limits, you must load the Maps API using an API key in order to purchase additional quota.

So whilst you don't need to have an API key it is useful if you want to monitor your usage and also required if you buy additional usage quota.