8. Klarna

No sale left behind

Founders: Sebastian Siemiatkowski, Niklas Adalberth, Victor Jacobsson
Launched: 2005
Funding: $338.6 million
Valuation: $2.3 billion
Disrupting: Electronic payments
Rival: PayPal

Sebastian Siemiatkowski, co-founder and CEO of Klarna
Source: Klarna.
Sebastian Siemiatkowski, co-founder and CEO of Klarna

Ask any online shopper the one thing they'd love to change about the experience, and chances are they'll tell you the onerous check-out process. Well, the founders of Klarna were listening. This 11-year-old Swedish e-commerce company has separated the process of buying from purchasing with its payment solution called Klarna Checkout. (Klarna roughly translates to "clear" in Swedish.)

Read MoreFULL LIST: 2016 DISRUPTOR 50

The company is already one of Europe's most highly valued tech start-ups, and now since moving into the United States late last year, it is gunning straight for its biggest stateside rival, PayPal. CEO Sebastian Siemiatkowski believes his company's password-free service and one-click shopping will help it compete in the crowded and highly-competitive U.S. market. And it's a market worth fighting for: Forrester Research says online retail sales are growing 10 percent annually and are projected to reach $480 billion by 2019.

Here's how Klarna's service works: A customer making an online purchase enters only their email address and Zip code to buy an item. Klarna pays the retailer immediately and then collects the amount due from the consumer within 14 days. The company makes its money predominately through the fees it charges merchants for its service. The company says that by using proprietary data analytics and modeling it can give approved consumers a seamless buying experience.

The company disclosed financials for the first time last year and reported that revenues increased to $331 million in 2015, from $260 million the year before. Investors like the company's chances in the U.S. market. So far, companies such as Sequoia Capital, General Atlantic and DST Global have invested more than $300 million.

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