Upon registering, the client selects the information they want to provide to the retailer and activates any available bonus or membership programs. With the consumer's permission, merchants can access personal data and use it for memberships and to provide personalized suggestions based on the customer's past purchases.

Named Sign-in with Klarna, the service, according to Klarna, is a challenge to the likes of Google and Apple in the online verification space because the tech giant's removal of third-party cookies has made it more difficult for payment providers to automatically fill in customer information in order to expedite the online checkout process.

After a test period during which it debuted with the restaurant app Maitres and the marketplace Tradera, the service has finally gone global. Within a few months, the service has risen to the position of second most popular login method on Tradera, as seen by 20% of all social logins attesting to its simplicity of use.

Tradera CEO Stefan Öberg states, "With just a few clicks, we receive a complete profile from the customer, while 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." "The new login service significantly simplifies registration for the majority of our customers, as the vast majority of Swedes already use Klarna."

Rusta, Casall, and NA-KD have been using Sign-in with Klarna since the beginning of the year. These organizations have expanded the feature set to include Norway, Finland, Denmark, the Netherlands, Austria, and Germany.