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.

• 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.

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.

• 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 .

• 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.

• 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.

• 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.