Retina.js is an open source script that makes it easy to serve high-resolution images to devices with retina displays.
http://retinajs.com/
JavaScript Libraries and Functions · Media
Get access to data on 1,759,357 websites that are Retina JS Customers. We know of 742,458 live websites using Retina JS and an additional 1,016,899 sites that used Retina JS historically and 369,812 websites in the United States.
Get a list of 1,759,357 websites using Retina JS which includes location information, hosting data, contact details, 1,162,858 currently live websites which includes 420,400 domains that redirect to sites in the list. 1,016,899 sites that used this technology previously and 369,812 websites in the United States currently using Retina JS.