On BuiltWith Trends we’ve used Quantcast for generating our trends charts across the top million sites which they consider are the most traffic’d sites on the internet. It is a useful resource and Quantcast provide those top million sites for free, without which sites like BuiltWith Trends would not be able to work.
Some people prefer Alexa’s top sites, others prefer Quantcast. We merged the Quantcast Top Million and the Alexa Top Million hoping to find most of the sites the same, the results were unexpected as the overlap was only around 400,000 sites. So from today, website lists will be offered in two varieties “Top Sites” and “Rest of Web”. Top Sites is an amalgamation of Alexa/Quantcast and some other sources of websites that make up the Internet’s top sites. This makes up a list of about 1.8 million unique websites we now track every week (we also track another 128 million less often).
The trends charts on BuiltWith Trends will still use the original Quantcast data as the million URLs in this list is a large enough dataset to provide an accurate trend of web technology usage on the Internet today.