DuckDuckGo, a privacy-focused search engine, has seen astronomic growth in traffic the last two years, a sign that could mean privacy is becoming a mainstream concern for people online after years as a fringe issue.

In fact, usage has grown 600% since 2013, DuckDuckGo CEO Gabe Weinberg told CNBC. Weinberg credits the uptick to the National Security Agency (NSA) leaks from the same year, which revealed widespread electronic surveillance by the U.S. government and created a demand for better privacy on the web.

Last year, He also attributed growth to Apple adding DuckDuckGo as the default search engine in devices running both iOS and OS X.

Internet giants like Facebook and Google have built their companies around their ability to gather customer data to sell ads, and DuckDuckGo represents the start of a backlash against that kind of business model.

The search engine differs from Google and other web services because it does not track users based on their search history. Instead, it sells advertising based only on the content of each individual search.

That means a search for men's shoes would be populated by ads from companies who bid on those search terms. However, companies can't target you differently based on whether you're a young man living in a city or a middle-aged dad in a suburb.

DuckDuckGo jumped to nearly 2 billion searches in 2014, up from a billion in 2013. But that's still a paltry sum compared to Google's stated "trillions" each year.