Final authorization

When integrating Klarna, the final authorization is a critical step when the step-up scenario occurs. This guide walks you through the creation of a transaction using the klarna_network_session_token provided by Klarna.

Token usage

Klarna now uses klarna_network_session_token as the required token to finalize a payment.

Existing integrations: Klarna previously relied on payment_token, which will continue to be returned in the current version for backward compatibility. Please note that payment_token will be removed in future versions, so if your integration currently uses it, plan to migrate to klarna_network_session_token.
New integrations: Acquiring Partners should ignore payment_token and use klarna_network_session_token exclusively.

Integration overview

After the customer completes their purchase via Klarna, the Payment Request transitions to the COMPLETED state. At this point:

Klarna returns a klarna_network_session_token which must be secured through Klarna Webhooks
You must use this klarna_network_session_token to authorize the payment within 60 minutes to finalize the transaction.
Successful authorization will generate a payment_transaction_id required for future transaction management.

Important: If you do not authorize within 60 minutes, the transaction will be invalidated.

The below diagram shows the customer journey and Acquiring Partner workflow, illustrating:

The handoff from Klarna to the Partner after purchase.
The sequence from receiving the Klarna Network session token to finalizing the payment.

Final authorization functions the same across all integration methods. If it has already been implemented—for example, with a server-only integration for one-time payments—it can be reused without modification.

Integration details

Call Payment Authorize API with klarna_network_session_token

The acquiring partner must use the klarna_network_session_token to perform a second call to Klarna's Payment Authorize API Klarna Icon .

Request parameters

Payment Authorize

POST:/v2/accounts/{partner_account_id}/payment/authorize

Show recommended

Parameter	Required	Description
`partner_account_id`	Yes	Unique account identifier assigned by Klarna to the onboarded merchant

Here you can find all required parameters for this operation authorizePayment

Sample Request

The klarna_network_session_token must be passed in the Klarna-Network-Session-Token HTTP header.

SHELL

curl https://api-global.test.klarna.com/v2/accounts/{partner_account_id}/payment/authorize \
-H 'Authorization: Basic <API key>' \
-H 'Content-Type: application/json' \
-H 'Klarna-Network-Session-Token: krn:payment:eu1:klarna-network-session-token:...' \
-d '{
      "currency": "USD",
      "request_payment_transaction": {
        "amount": 11800,
        "payment_transaction_reference": "acquiring-partner-transaction-reference-1234"
      }
    }'

Handling Klarna's response

Upon successful authorization, the response body includes the payment_transaction_id, which you'll use for payment transaction management actions.

The endpoint is idempotent, so repeated requests with the same token return the same result, ensuring safe retries.

Response parameters

Payment Authorize

POST:/v2/accounts/{partner_account_id}/payment/authorize

Show recommended

Parameter	Required	Description

Here you can find all required parameters for this operation authorizePayment

Sample response

JSON

{
  "payment_transaction_response": {
    "result": "APPROVED",
    "payment_transaction": {
      "payment_transaction_id": "krn:payment:eu1:transaction:6debe89e-98c0-[...]",
      "payment_transaction_reference": "acquiring-partner-transaction-reference-1234",
      "amount": 11800,
      "currency": "USD",
      "payment_funding": {...},
      "payment_pricing": {...},
      "expires_at": "2025-10-30T19:26:02.772Z"
    }

API & SDK references

Authorize a payment transaction.