Alexa's certified program and pro metrics.
http://www.alexa.com/siteowners/certify
Analytics and Tracking · Audience Measurement · Visitor Count Tracking
Get access to data on 273,848 websites that are Alexa Certified Site Metrics Customers. We know of 18,231 live websites using Alexa Certified Site Metrics and an additional 255,617 sites that used Alexa Certified Site Metrics historically and 6,073 websites in the United States.
Get a list of 273,848 websites using Alexa Certified Site Metrics which includes location information, hosting data, contact details, 18,231 currently live websites and an additional 34,805 domains that redirect to sites in this list. 255,617 sites that used this technology previouslyand 6,073 websites in the United States currently using Alexa Certified Site Metrics.
Countries
Financial
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Region
These are sites that we think might use Alexa Certified Site Metrics in the future because of their similarity to other sites that already do.