1. Set up your Klarna account and credentials

Ensure seamless Klarna Payments integration for your platform with this checklist.

Follow this checklist to ensure a complete integration of Klarna Payments for web, mobile, and in-store channels. This guide covers a direct integration with Klarna’s APIs and progresses from initial setup to production readiness, highlighting key decisions and best practices.

Create a Klarna test account: Sign up for a Klarna developer account and access the Klarna test Merchant Portal.
Generate API credentials: Use the API key generation instructions to retrieve your test and live credentials.
Get the correct API endpoints: Refer to the API base URLs page for the correct environment and regional endpoints.
Enable the Klarna test environment: Use the Playground environment for testing.
Familiarize yourself with Klarna’s API docs: Visit the Klarna API documentation to understand endpoints, data models, and error handling.

2. Choose your integration approach

Select your platform(s): Klarna supports Web, Mobile (iOS/Android), and In-store Payments. See the Payments overview.
Plan your Web integration: Klarna offers solutions for in-line integration and hosted payment page.
Plan your Mobile integration: Use Klarna’s Mobile SDKs or embed the Web integration via WebView.
Plan your In-store integration: Use Klarna’s In-store API for QR-code-based or link-based payments.
Decide on payment scenarios: See Recurring Payments guide for how to handle subscriptions or repeat purchases.

3. Build your Online Payments integration

Implement Klarna Payments using the in-line widget integration for Web and the Klarna Mobile SDKs for iOS and Android.

Initiate a payment creates a session that identifies the purchase towards Klarna.
Check out displays Klarna as a payment method and authorizes the purchase.
Create an order uses the authorized payment from the previous step and creates an order.
The payment process has slight variations according to each scenario one-time or recurring payments.

Mobile (native SDKs)

Set up: Install the Klarna SDK for iOS or Android using your platform’s package manager.
Initiate payment (Server-side): Your backend creates a payment session and passes the client_token to your app.
Render payment view (Mobile App): Present Klarna’s native view to display Klarna in your checkout.
Authorize the session (Mobile App): Trigger the authorization through the SDK and handle the callback.
Create an order (Server-side): Use the resulting authorization_token in your backend to finalize the payment and create an order .

4. Build your Post Purchase integration

View and change orders: Use the Order management API to read and update the details of an order.
Capture and track orders: capture your orders and add shipping information for tracking.
Refund orders and manage authorizations: refund and manage orders efficiently using the Klarna Order Management API.
Reconcile settlements: Settlement reports are provided via the Merchant Portal Settlements App, the Settlements API or via a pre-configured SFTP.
Customer support readiness: Learn dispute handling and refund workflows.

5. Test and optimize your integration

Exercise all test scenarios: Complete these End-to-end test cases in Playground.
Follow Klarna’s UX guidelines: Implement Klarna's UX Guidelines and improve your conversion with On-site messaging, Express checkout and Sign in with Klarna.
Verify frontend behavior: Test Klarna widget or SDK behavior on all platforms.
Escalation and retry policy: Ensure all backend calls are as robust and fail-safe as possible.
Test failure and recovery paths: Simulate expired sessions and API errors. See error codes reference.
Review in the Merchant Portal: Use the Playground portal to validate test transactions.
Performance and fallback testing: Performance test your integration, considering Klarna's rate limit policy and SLAs.
Security testing: Ensure no credentials or PII are exposed. All traffic must use HTTPS.

6. Go live and monitor

Obtain production API credentials: Use the live API key in production.
Run final verification in production mode: Complete the go-live checklist in production.
Review compliance and legal requirements: Ensure checkout and messaging comply with design and legal standards.
Implement Klarna branding: Add Klarna promotional assets to your site.
Monitor orders and payments: Check that all orders appear and payouts reconcile.

For more information, see the Klarna Payments documentation.