Klarna, a London based installment financing provider and challenger bank, said it surpassed 3 million active users in the U.K. and 170,000 retail merchants worldwide. 

The company also said that in-store transactions rose by 300% during the first half of 2019 and said 6,000 merchants around the world accept Klarna in-store. 

"The growth we've seen since launching in the U.K. has been astounding, but I'm particularly proud of what we've been able to achieve in the last 12 months," Luke Griffiths, general manager at Klarna U.K., said in a company release. 

Klarna allows merchants to offer installment plan financing on digital and in-store purchases, including major brands like Michael Kors, Samsung, Topshop, Abercrombie & Fitch and other brands.