In case an order includes additional cost due to shipping these should be detailed in the order_lines as an additional product.

In order to clearly indicate that the object is associated to shipping fees and not to an specific product, you should indicate "type": "shipping_fee". Additionally, as a good practice we recommend to set the name of the corresponding also as "Shipping" or any variation that allows a clear understanding to the customer what this line is about.

The customer will be able to see this level of details in their post purchase experience, including Klarna app.

This will ensure a transparent and accurate checkout experience for your customers as well as better post purchase experience.

Let's break it down into simple steps:

1 - Identify the shipping costs: Before you can send the shipping fee information through the API, you need to determine the shipping costs associated with the customer's order. This can vary based on factors like destination, delivery method, and package weight.

2- Validate you checkout experience: Within your checkout system, ensure that you have a field or method to calculate the shipping costs before the final checkout stage. This should be dynamic, adjusting in real-time as customers change their shipping preferences.

3- Modify the Klarna Payments API Request: In your API request to Klarna, you'll include the shipping costs as a separate line item. order_lines object should be included in the creation of the session request as well as in the creation of the order request. Here's a simplified example of how to structure this in your payload:

{
  "order_amount": 10000,
  "order_tax_amount": 2000,
  "order_lines": [
    {
      "type": "physical",
      "name": "Product Name",
      "quantity": 1,
      "unit_price": 8000,
      "tax_rate": 2500,

4 - Testing: Before going live, thoroughly test the integration in a sandbox environment to ensure the shipping costs are correctly calculated and displayed to the customer. Klarna provides a test environment for this purpose.

5 - Go Live: Once testing confirms that everything is working as expected, you can proceed to deploy the changes to your live environment. Keep an eye on the first transactions to ensure all data is transmitted correctly.