Quantcast is a free service that lets you check out the audience, interests, and demographics of visitors to over 100 million websites. “Measure + Advertise” is Quantcast’s tagline.
While the data is not totally accurate just yet, Quantcast is working hard to give advertisers a peek behind the curtains. You can see whether websites are a good fit for your community, vis-à-vis traffic and demographics, before you commit your ad dollars.
Any website that installs the Quantcast tracking code is identified as “quantified”. The tracking code provides visitor intelligence that Quantcast spins into reports.
For sites that do not have the tracking code, Quantcast uses third-party data, from ISPs and others, to generate estimates.
Here’s the backstory about Quantcast. Two guys – Konrad Feldman, with a background in financial fraud, and Paul Sutter, an expert at building systems to handle a ton of data, raised $60 million plus to transform the online advertising space.
According to Wikipedia, the firm was founded in 2006 as “The World’s Only Open Internet Ratings Service” that recognizes that reliable data is needed to make the most intelligent online media buys.
Quantcast is free to use.