Please use the test environment to test your Klarna Checkout integration. Purchases completed in the test environment are not processed by our production system and will not result in proper invoices or any fees collected on invoices.
The API URLs / end-points for our playground environment are found here
Use any fake test data you like, just make sure it passes our validations for example postal code format.
Do not use any real personal details in our playground environment- data is saved and if another user is using the same email + zip combination they might get prefilled with your test data.