Quantcast, the San Francisco-based online traffic measurement firm, has received a big $20 million second round funding. The round was led by Founders Fund (Peter Thiel’s fund) and Polaris Venture Partners. The company’s technology combines directly measured traffic statistics with multiple panel data sources, it says. It competes with the established players like Comscore (NSDQ: SCOR), Netratings and Hitwise, and startups like Compete. The company says it has clients such as Fox, CBS (NYSE: CBS), Belo (NYSE: BLC) Corporation, AccuWeather, Slide, and IDG.

SEE ALSO: Net Ratings Provider Quantcast Receives $5.7 Million In First Round

It raised a $5.7 million first round last year, from Founders Fund and Revolution Capital.