On registration, the customer chooses what data they wish to share with the merchant, and sign-up to any membership or bonus programmes on offer. Merchants gain access to personal data with consent from the consumer and can use it for memberships and to give consumers personal recommendations based on their purchase history.

Klarna says the service, dubbed Sign-in with Klarna, presents a challenge to the likes of Apple and Google in the online verification industry since the tech giant's elimination of third-party cookies has made it harder for payment services to automatically fill in customer details to speed the online checkout.

The service has now launched globally after launching first with restaurant app Maitres and the marketplace Tradera during a test period. After just a few months, the service has become the second most popular login method on Tradera, with 20% of the total social logins demonstrating its usability and ease.

“We immediately get a complete profile with just a couple of clicks from the consumer, whereas similar services from Apple, Facebook, and Google create a profile that the customer needs to complete since it lacks information such as address and phone number," says Stefan Öberg, CEO at Tradera. "The vast majority of Swedes already use Klarna, and the new login service thus significantly simplifies registration for the majority of our customers,” .

Since the turn of the year, Sign-in with Klarna has been implemented at Rusta, Casall, and NA-KD, who have rolled out the functionality in Norway, Finland, Denmark, Netherlands, Austria, and Germany.