Can I get a list of top sites from an API?

Yes. The Alexa Top Sites web service provides programmatic access to Alexa’s top sites data.

Using this service you can get lists of top sites globally or in a specific country.  The web service also returns the rank, reach, and pageviews per million data within a specific country.

To use the Alexa Top Sites service you will need to sign up for the service by clicking on the “Sign up for Alexa Top Sites” button on this page: http://aws.amazon.com/alexatopsites/

The best way to get started is to read the Technical documentation here:

http://docs.amazonwebservices.com/AlexaTopSites/latest/

And then modify one of the sample programs here to get the data you are interested in:

http://aws.amazon.com/code/Alexa-Top-Sites