Java SDK library for Klarna Services
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Klarna REST Java SDK

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Welcome to Klarna. Smoooth payments.

Klarna Checkout

A full checkout experience embedded on your site. It lets your customers check out on your site with only their email and ZIP, and pay with the major payment methods including the specific Klarna payment methods. All available in one integration.

Klarna Payments

Klarna offers three payment methods. Pay now, Pay later and Slice it. It offers your consumers to try before they buy, finance purchases on your store, or make use of other payment options made available by Klarna.

Getting started

SDK covers all of Klarna API:


API Credentials

Before getting a production account you can get a playground one. Register here to be able to test your SDK integration before go live:

Later you need to register as a Klarna merchant to get a production credentials

Installing the Java SDK

The Java SDK requires Java 1.7 version or higher.


To install the Java SDK from the Central Maven repository using Maven, add the following lines to pom.xml:



To install the Java SDK from the Central Maven repository using Gradle, add the following lines to build.gradle:

dependencies {
    compile group: 'com.klarna', name: 'kco-rest', version:'3.0+'


The various documentation is available:


Example files can be found in the examples package.

The basic workflow is the following:

  1. Create an SDK Client

  2. Build the new API instance via created Client

     * Klarna Checkout Example
    public class App
        public static void main( String[] args )
            Client client = new Client("username", "password", HttpTransport.EU_BASE_URL);
            CheckoutOrdersApi checkoutOrdersApi = client.newCheckoutOrdersApi();
            try {
                CheckoutOrder order = checkoutOrdersApi.fetch("checkoutOrderID-123");
                // Order has been successfully fetched, we can get some info, e.g. HTML Snippet
                // This snippet can be embedded into your website/templates/etc
                String htmlSnippet = order.getHtmlSnippet();
                // Or print a whole order data
            } catch (IOException e) {
                System.out.println("Connection problem: " + e.getMessage());
            } catch (ApiException e) {
                System.out.println("API issue: " + e.getMessage());

Logging and Debugging

The Java SDK uses the slf4j library as an abstraction for various logging frameworks. We have not provided any back-end implementation. Choose an implementation that applies to your project.

For more information, see the slf4j documentation.

You can debug and check all the requests and responses made via the SDK. In order to enable debug mode you need to change the logging level of your Logger to "debug".

For example, if you use log4j2 logger, put this line to your file:

rootLogger.level = debug

The output will look like:

[18-Oct-25 14:16:09:652] [DEBUG] [HttpUrlConnectionTransport:312] - DEBUG MODE: Request
Headers: Headers: {User-Agent=[Language/Java_1.8.0_161 (Vendor/Oracle Corporation; VM/Java HotSpot(TM) 64-Bit Server VM) Library/Klarna.kco_rest_java_3.0.0 OS/Mac OS X_10.13.4], Content-Type=[application/json]}

DEBUG MODE: Response
Headers: {null=[HTTP/1.1 200 OK], Server=[openresty], Connection=[keep-alive], Vary=[Accept-Encoding], Content-Length=[166], Date=[Thu, 25 Oct 2018 12:16:09 GMT], Content-Type=[application\/json]}
Payout: {"status" : "ACTIVE","payment_method_type" : "INVOICE"}

How to contribute

At Klarna, we strive toward achieving the highest possible quality for our products. Therefore, we require you to follow these guidelines if you wish to contribute.

To contribute, the following criteria needs to be fulfilled:

  • Description regarding what has been changed and why
  • Pull requests should implement a boxed change
  • All code and documentation must follow the style specified by the included configuration (src/checkstyle.xml)
  • New features and bug fixes must have accompanying unit tests:
    • Positive tests
    • Negative tests
    • Boundary tests (if possible)
    • No less than 90% decision coverage
  • All unit tests should pass

Questions and feedback

If you have any questions concerning this product, please contact


The Klarna Checkout REST Java SDK is released under Apache License, Version 2.0