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Klarna payments - Implementation guide - existing customer

Target Audience: Developers


This document describes how you integrate Klarna Payments in your web applications using the Payway API. The integration towards Payway is API-based which means you do not need a Payway session to use this integration, an access token is sufficient.

Before you start planning and writing code

Please read Getting started checklist

Requirements and limitations

  • At the moment only available in Sweden
  • An access token connected to an identity for the user about to do the purchase with scope /external/klarna_payments/w
  • HTTPS on the purchase page

Initial Payment flow


1. User requests purchase

The user must actively choose to purchase a package before you render request a purchase session. This can for example be done simply by having simply informing the user that he has hit the paywall and needs to buy access buy clicking a button. You should NOT create a purchase session each time the user hits the Paywall.

2. Create session

To proceed with rendering the Klarna payment box you must first create a session for a package or campaign using the Payway API. You also supply a confirmation url where the user should be sent at the end of the purchase flow.

A session is valid for 48 hours, and will be invalidated immediately if a successful purchase is made.

See Create Session API for details on performing the request.

3. Render purchase page

Once you have the klarna_client_token you are ready to build the Klarna Payment Widget on your purchase page. More details on how you do this can be found in the Klarna documentation. The Example app also contains a working implementation of the Klarna Payment Widget.

4. Authorize purchase against Klarna

When the user presses the buy button you must, using javascript, perform an authorize call to Klarna. You will in return get a authorization_token.

Example without error handling:

var btn = document.getElementById("approve_purchase");
var klarna_authorization_token_input = document.getElementById('klarna_authorization_token');
var form = document.getElementById('authorize_form');
var payment_method_category = 'direct_debit/pay_now or any of the payment methods available to you in your Klarna payments setup.'

btn.addEventListener("click", function() {
    payment_method_category: payment_method_category
},{}, function (response) {
    if(response.approved) {
        klarna_authorization_token_input.value = response.authorization_token;
        form.submit(); //post the authorization token to your backend

More details on how to do the authorize call can be found in Klarna documentation. The Example app also contains a working example of how to do the authorize call.

Note that you should not create any customer token yourself (3.3 Create Customer Token). You should simply forward the authorization token to the Payway API Place Order.

5. Place order

Once you you have done the authorize call and sent the authorization token to you backend you are ready to place the order. The place order will charge the Payment from Klarna and create the order, payment and subscription in Payway.

Trial order

If you want to sell a free campaign that transitions to a standard package please use Place trial order API.
Be aware that trial orders are only supported when initiating the klarna widget with direct debit.

Regular order

If you want to sell a regular campaign or package please use Place order API

6. Update account details

After the order has been placed we fetch account and order information from klarna and complement the Payway account with available properties. See below for more info on what paramters are updated.

How and when is account information from Klarna synced with Payway

  • Account information from Klarna always takes precedence. To disable this behaviour please set disable_account_info_overwrite=true when creating the session.
  • During trial purchases we do not receive any account information from Klarna until the first recurring charge.

What information is updated

Property Description
Account address The billing address of the klarna order
Name First name and last name as set in the billing address of the klarna order
Birth date Birth date of the customer attached to the klarna order
Ssn National identification number of the customer attached to the klarna order
Mobile phone number Mobile phone number of the customer attached to the klarna order
Delivery address The delivery address of the klarna order

Custom error handling

You can configure Payway to raise an error if certain conditions are met during the account update. If either of the parameters below are set to true and an exception occurs in either operation the purchase will not be completed.

Parameter Description Default value
raise_on_ssn_already_taken_error If set to true the request will raise an exception if the ssn is already taken by another user in Payway true
raise_on_ssn_already_set_error If set to true the request will raise an exception if an ssn update is performed on a user with an ssn false
raise_on_account_update_error If set to true the request will raise an exception if errors are encountered during an account update. An account update consists of "name", "birth date" and "account address" updates. false
raise_on_delivery_address_error If set to true the request will raise an exception if errors are encountered during the order delivery address validation false

7. Redirect the user to Klarna

You should redirect the user to the redirect uri that you received in the previous step. The reason for this redirect is to allow Klarna to recognize the customer's device in future interactions. The user does not need to do any interaction in this step.

8. Show confirmation

After visiting Klarna the browser will be sent to the confirmation url that you gave in step 2.


The klarna integration adheres to the common error conventions of the Payway API.

See common error responses

Errors that we know of and are specific to Klarna.

403 - Payment method failed

Reasons for this error can be:

  • Customers are in debt when Klarna does an external lookup.
  • Customers are in debt to Klarna.
  • Customer did not pass Klarna risk policy assessment.

Action taken due to error

  • Subscription terminated

Example app

Sample app