One-click payments with Klarna Web SDK (Solidgate orchestrated)

Charge a returning customer's saved Klarna option in a one-click, customer-initiated transaction using the Klarna Web SDK, where Solidgate orchestrates the charge. Restore the saved option from the Klarna Customer Token, present Saved and Pick plan, and charge through Solidgate.

This guide explains how to charge a returning customer's saved Klarna option in a one-click, customer-initiated transaction using the Klarna Web SDK, where you present Klarna in your own checkout and Solidgate orchestrates the charge. The customer is at checkout and has a stored Klarna Customer Token, so Klarna can be pre-selected as a one-click "Saved" option.

You restore the saved option from the Klarna Customer Token before presenting, then charge through Solidgate: because Solidgate initiates the charge, the charge is authorized on the Solidgate token — Solidgate's own token identifier, which it maps server-side to the Klarna Customer Token it holds. You still present the saved option with the Klarna Customer Token, but the Solidgate token carries the charge. You never call Klarna's authorize yourself. Klarna may still require a step-up based on risk; when it does, the Web SDK guides the customer through a short Klarna Purchase Journey before Solidgate authorizes the charge.

For the full Web SDK setup (loading the SDK, rendering the payment selector, button styling), follow Build checkout form with Klarna Web SDK (Solidgate orchestrated). This page covers only the saved-option specifics. To compare all tokenized flows, see the Tokenized payments overview.

Prerequisites

Before you integrate, check that you meet the following prerequisites:

1.
Ensure that you have Klarna enabled with Solidgate.
2.
A stored Solidgate token for the customer — Solidgate's own token identifier that authorizes the charge — and a Klarna Customer Token issued with the payment:customer_present scope to present the saved option (see Create a Klarna Customer Token).
3.
Confirm you have access to the Klarna Partner Portal with a client identifier (domain allowlisted) and an API key able to generate a Klarna Network Session Token.
4.
Add Terms and Conditions covering saved payment methods.

Integration overview

1.
Generate a Klarna Network Session Token from the stored Klarna Customer Token.
2.
Initialize the Klarna Web SDK with the Klarna Network Session Token and request the payment presentation — Klarna returns the customer's saved option with a PRESELECT_KLARNA instruction.
3.
Render Saved (pre-selected) and Pick plan in your payment selector.
4.
The customer selects the saved option; the initiate callback returns the klarnaNetworkSessionToken and the paymentOptionId.
5.
Charge through Solidgate, passing the Solidgate token, the klarnaNetworkSessionToken, and the paymentOptionId in klarna_network_data.
6.
Solidgate resolves the Solidgate token to the Klarna Customer Token and authorizes the charge with Klarna behind the scenes.
7.
If customer authentication is required, Solidgate returns a payment_request_url. Forward it to the Klarna Web SDK, which launches the Klarna Purchase Journey; once the customer completes it, Solidgate finalizes the charge.
8.
When the charge completes, Solidgate sends an order completed notification — show the order confirmation and record the successful charge.

sequenceDiagram autonumber participant C as Customer participant P as Partner participant K as Klarna participant AP as Solidgate C->>P: Visits checkout page P->>K: Generate Klarna Network Session Token<br/>POST network/session/tokens Note over P,K: Header: Klarna-Customer-Token K-->>P: Return klarna_network_session_token P->>K: Initialize Klarna Web SDK Note over P,K: klarnaNetworkSessionToken K-->>P: Return payment methods and instruction P->>P: Display Klarna payment methods C->>P: Click Klarna payment button K->>P: Trigger initiate callback Note over K,P: (new) klarna_network_session_token<br/>paymentOptionId P->>AP: Create payment Note over P,AP: Solidgate token<br/>(new) klarna_network_session_token<br/>klarna_network_data: payment_option_id alt If customer authentication is required AP-->>P: Return payment_request_url P->>K: Forward payment_request_url to Klarna Web SDK K->>C: Launch Klarna purchase journey C->>K: Complete Klarna purchase journey end AP-->>P: Order completed notification P-->>C: Display confirmation message

Integration details

Restore and present the saved Klarna option

1.
Generate a Klarna Network Session Token from the Klarna Customer Token. Before initializing the Web SDK, call the Generate Klarna Network Session Token endpoint server-side (POST /v2/network/session/tokens) with the stored Klarna Customer Token in the Klarna-Customer-Token header. The returned Klarna Network Session Token carries the customer's saved Klarna context and is directly Web SDK-compatible.
2.
Initialize the Web SDK with the Klarna Network Session Token so the payment presentation returns the saved option.
3.
Render the saved option. With a Klarna Customer Token context present, the presentation returns a savedPaymentOption (in addition to the default paymentOption) with the PRESELECT_KLARNA instruction. Render the Saved option before the default option and pre-select it; the default option becomes the Pick plan entry.

The Klarna Customer Token is required to present the saved option. Use it to generate a Klarna Network Session Token via generateKlarnaNetworkSessionToken. The Klarna Customer Token is a durable credential — generating a session token does not consume it, so you can reuse it to generate more.

Chain a session token from Boost features. If you already hold a Klarna Network Session Token obtained when the customer interacted with a Boost feature (for example On-site messaging or Sign in with Klarna) earlier in the checkout, chain it: call generateKlarnaNetworkSessionToken with both that session token in the Klarna-Network-Session-Token header and the Klarna Customer Token in the Klarna-Customer-Token header. The returned session token is what you use to initialize the SDK, preserving session continuity across the checkout.

The recommended presentation when a Klarna Customer Token is available:


Saved Klarna option (pre-selected)	Pick Plan selected

Prioritize the savedPaymentOption by placing it before the default paymentOption. Pre-select it on PRESELECT_KLARNA, and show it as the only option on SHOW_ONLY_KLARNA.

JAVASCRIPT

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function renderKlarna(paymentPresentation) {
  const { paymentOption, savedPaymentOption, instruction } = paymentPresentation;

  // Render the saved option first (Saved), then the default option (Pick plan)
  if (savedPaymentOption) renderKlarnaOption("klarna-option-saved", savedPaymentOption);
  if (paymentOption)      renderKlarnaOption("klarna-option-default", paymentOption);

  const primaryId = savedPaymentOption ? "klarna-option-saved" : "klarna-option-default";

  if (instruction === "PRESELECT_KLARNA" || instruction === "SHOW_ONLY_KLARNA") {

Charge the saved option through Solidgate

When the customer selects the saved option, the initiate callback returns the klarnaNetworkSessionToken and the paymentOptionId. You charge Solidgate directly to finalize the payment.

Field	Presence	Description
Charge credential	required	The Solidgate token — Solidgate's own token identifier. Because Solidgate initiates the charge, the charge is authorized on the Solidgate token; Solidgate resolves it server-side to the `klarna_network_customer_token`.
`klarnaNetworkSessionToken`	required	The session token returned by the `initiate` callback.
`klarna_network_data`	required	Array carrying the selected `paymentOptionId` — `"[paymentOptionId, ...]"`. Mandatory to charge the saved one-click option.

BASH

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curl -X POST https://api.acquiring-partner.com/payment \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 1000,
    "currency": "USD",
    "payment_methods": {
      "klarna": {
        "<acquiring-partner token>": "",
        "klarna_network_session_token": "",
        "klarna_network_data": "[paymentOptionId, ...]"

Solidgate resolves the Solidgate token to the klarna_network_customer_token and authorizes the charge with Klarna behind the scenes. Refer to Solidgate's API reference for the exact field names and response contract.

Handle the outcome

Outcome	What it means	Next step
Order completed	Klarna authorized the charge and Solidgate sends an order completed notification.	Display the confirmation page and record the successful charge.
Declined	Klarna did not authorize the charge.	Surface a retry/alternative payment to the customer.
Authentication required	Klarna needs the customer to complete a short Klarna Purchase Journey before the charge can be finalized; Solidgate returns a `payment_request_url`.	Forward the `payment_request_url` to the Klarna Web SDK to launch the Klarna Purchase Journey. Once the customer completes it, Solidgate finalizes the charge and sends the order completed notification.

A saved-option one-click charge often completes directly, but Klarna may require customer authentication based on risk — handle the authentication-required outcome above so the customer can complete the Klarna Purchase Journey. If you instead present Klarna as a one-time payment (no Klarna Customer Token), follow Build checkout form with Klarna Web SDK (Solidgate orchestrated).

Build checkout form with Klarna WebSDK (Solidgate orchestrated)

Tokenized payments overview

Create a Klarna Customer Token (Partner orchestrated)

1. General