Israeli data outfit SimilarWeb has closed a $15 million Series D funding round.

The round was lead by existing shareholders Naspers and Lord David Alliance, and takes the company's total investment since 2009 to $40 million.

Secret sauce

The company's key product is SimilarWeb Pro, which enables companies to compare web traffic and, more importantly, sources of traffic.

This new investment will enable SimilarWeb to aggressive expand its technology into mobile app analytics, notably app store trends and traffic sources, both internal and external to these stores.

It also hopes to make what it refers to as "targeted acquisitions in the mobile arena".