Complete Klarna Order

POST https://api.firmly.work/api/v1/domains/{domain}/express/klarna/complete-order

​​ Overview

Completes the checkout process by placing an order with the merchant using the Klarna authorization. This is the final step in the Klarna checkout flow. The endpoint validates the authorization token, places the order, and returns the order confirmation with the merchant’s order number.

Availability and the host this endpoint runs on are covered in the Klarna Express Checkout overview.

​​ Authentication

• x-firmly-authorization (string, required) — Device access token from Browser Session

​​ Path Parameters

• domain (string, required) — The merchant domain (e.g., “staging.luma.gift”)

​​ Request Body

• attributes (object, required) — Klarna payment attributes
  Attributes

  • authorization_token (string) — Conditionally required. The Klarna authorization token. Required unless a prior Authorize call already stored it in the session — in that case it is retrieved automatically and may be omitted.
  • transaction_token (string) — Alternative to authorization_token.
  • redirect_result (string) — The result of a Klarna redirect flow. Also an accepted alternative: any one of the three satisfies the requirement, and each is forwarded to the merchant when supplied.

​​ Response

Returns the order confirmation object.

• cart_id (string) — Unique identifier for the cart

• platform_order_number (string) — The order number from the merchant platform

• cart_status (string) — Status of the cart (e.g., “submitted”)

• submitted_at (string) — ISO timestamp when the order was submitted

• display_name (string) — Merchant’s display name

• platform_id (string) — Identifier of the merchant’s underlying commerce platform. The literal value varies by merchant.

• shop_id (string) — Merchant domain

• urls (object) — Relevant URLs for the order

  URLs

  • thank_you_page (string) — URL to the merchant’s order confirmation page

• line_items (array) — Array of items in the order

  Line Item Details

  • line_item_id (string) — Unique identifier for the line item
  • sku (string) — Product SKU
  • quantity (number) — Quantity ordered
  • description (string) — Product description
  • price (object) — Unit price
  • line_price (object) — Total price for this line item
  • image (object) — Product image information

• shipping_info (object) — Delivery address details

• billing_info (object) — Billing address details

• shipping_method (object) — Selected shipping method with pricing

• payment_summary (object) — Summary of the Klarna payment

  Payment Summary

  • payment_type (string) — Always "Klarna" for this gateway
  • attributes (object) — Klarna session details

  Attributes

  • session_id (string) — Klarna payment session identifier
  • authorization_token (string) — The authorization token used for this order

• total (object) — Grand total including all costs

• sub_total (object) — Subtotal before shipping and tax

• shipping_total (object) — Shipping cost

• tax (object) — Tax amount

• cart_discount (object) — Total discount applied

​​ Code Example

const response = await fetch(
  'https://api.firmly.work/api/v1/domains/staging.luma.gift/express/klarna/complete-order',
  {
    method: 'POST',
    headers: {
      'x-firmly-authorization': authToken,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      attributes: {
        authorization_token: 'klarna_auth_token_from_widget'
      }
    })
  }
);

const order = await response.json();
console.log('Order number:', order.platform_order_number);

// Redirect to thank you page
if (order.urls?.thank_you_page) {
  window.location.href = order.urls.thank_you_page;
}

import requests

response = requests.post(
    'https://api.firmly.work/api/v1/domains/staging.luma.gift/express/klarna/complete-order',
    headers={
        'x-firmly-authorization': auth_token,
        'Content-Type': 'application/json'
    },
    json={
        'attributes': {
            'authorization_token': 'klarna_auth_token_from_widget'
        }
    }
)

order = response.json()
print(f"Order placed: {order['platform_order_number']}")
print(f"Thank you page: {order['urls']['thank_you_page']}")

curl -X POST https://api.firmly.work/api/v1/domains/staging.luma.gift/express/klarna/complete-order \
  -H "x-firmly-authorization: YOUR_AUTH_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"attributes": {"authorization_token": "klarna_auth_token_from_widget"}}'

​​ Response Example

{
  "cart_id": "9cf76530-1344-420f-9ca6-c7a96fb6db45",
  "platform_order_number": "6800018416",
  "cart_status": "submitted",
  "submitted_at": "2026-07-22T18:58:25.000Z",
  "display_name": "Example Store",
  "platform_id": "example_commerce",
  "shop_id": "staging.luma.gift",
  "urls": {
    "thank_you_page": "https://staging.luma.gift/order/confirmation"
  },
  "line_items": [
    {
      "line_item_id": "3e66bef5-43f5-4a80-8957-91c5c8233163",
      "sku": "MT12",
      "quantity": 1,
      "description": "Cassius Sparring Tank",
      "price": {
        "currency": "USD",
        "value": 18,
        "number": 1800,
        "symbol": "$"
      },
      "line_price": {
        "currency": "USD",
        "value": 18,
        "number": 1800,
        "symbol": "$"
      },
      "image": {
        "url": "https://staging.luma.gift/images/products/mt12-blue_main.jpg"
      },
      "msrp": {
        "currency": "USD",
        "value": 21.6,
        "number": 2160,
        "symbol": "$"
      }
    }
  ],
  "shipping_info": {
    "first_name": "John",
    "last_name": "Smith",
    "email": "john@example.com",
    "phone": "(206) 555-1212",
    "address1": "123 Main St",
    "city": "Seattle",
    "state_or_province": "WA",
    "country": "US",
    "postal_code": "98101"
  },
  "billing_info": {
    "first_name": "John",
    "last_name": "Smith",
    "email": "john@example.com",
    "phone": "(206) 555-1212",
    "address1": "123 Main St",
    "city": "Seattle",
    "state_or_province": "WA",
    "country": "US",
    "postal_code": "98101"
  },
  "shipping_method": {
    "id": "s2_2_day",
    "description": "2-Day Shipping",
    "price": {
      "currency": "USD",
      "value": 12,
      "number": 1200,
      "symbol": "$"
    }
  },
  "payment_summary": {
    "payment_type": "Klarna",
    "attributes": {
      "session_id": "kp_abc123def456",
      "authorization_token": "klarna_auth_token_from_widget"
    }
  },
  "total": {
    "currency": "USD",
    "value": 34,
    "number": 3400,
    "symbol": "$"
  },
  "sub_total": {
    "currency": "USD",
    "value": 18,
    "number": 1800,
    "symbol": "$"
  },
  "shipping_total": {
    "currency": "USD",
    "value": 12,
    "number": 1200,
    "symbol": "$"
  },
  "tax": {
    "currency": "USD",
    "value": 2,
    "number": 200,
    "symbol": "$"
  },
  "fees": [
    {
      "description": "Recycle fee",
      "currency": "USD",
      "value": 2,
      "number": 200,
      "symbol": "$"
    }
  ],
  "fee_total": {
    "currency": "USD",
    "value": 2,
    "number": 200,
    "symbol": "$"
  },
  "cart_discount": {
    "currency": "USD",
    "value": 0,
    "number": 0,
    "symbol": "$"
  }
}

​​ Related Endpoints

• Start Klarna Checkout — Create Klarna session
• Authorize Klarna Checkout — Confirm authorization
• Complete Order (Credit Card) — Alternative credit card flow

​​ Error Responses

Errors return a JSON body with code, error, and description. Program against the error value — descriptions are human-readable and may change.

{ "code": 400, "error": "BadRequest", "description": "Missing Klarna authorization_token or transaction_token" }

{ "code": 412, "error": "CheckoutError", "description": "Payment info or billing address invalid." }

{ "code": 412, "error": "MissingShippingMethod", "description": "Shipping method needs to be set." }

{ "code": 412, "error": "MissingTaxSync", "description": "The taxes are not synced yet. Please refresh the cart and try again." }

{ "code": 422, "error": "CreditCardDeclined", "description": "Credit card declined" }

{ "code": 400, "error": "InvalidToken", "description": "Jwt token is invalid." }

{ "code": 401, "error": "InvalidJWTToken", "description": "Jwt token is invalid." }

{ "code": 404, "error": "CartNotFound", "description": "Cart was not found." }

{ "code": 404, "error": "DomainNotFound", "description": "This domain was not found in firmly servers." }

{ "code": 404, "error": "GatewayNotFound", "description": "Payment gateway 'klarna' not found" }

{ "code": 412, "error": "OperationNotSupported", "description": "This operation is not supported for this store." }

{ "code": 503, "error": "StoreUnavailable", "description": "Store temporarily unavailable. Please try again later." }

{ "code": 429, "error": "RateLimited", "description": "Too many requests. Please try again later." }