checkoutSession

HTTP method: POST

The checkoutSession method creates a checkout session for the current customer's basket grouping all available payment methods. The session should be reused for different payment methods until the payment is not finalized.

Checkout session is used to improve fraud detection and help maximize conversion rate.

Test URL https://testgateway.altapaysecure.com/merchant/API/<method>
Production URL https://<YourShopName>.altapaysecure.com/merchant/API/<method>

The request extends request body of method createPaymentRequest

The table below presents only parameters that are not present in the createPaymentRequest

Parameter Description Type Notes
terminals List of terminals that are available for the user based on the checkout parameters (available PaymentMethods for user) Array
session_id Optional identifier for a session to be created. If not provided, the identifier will be generated automatically. String{0,50} The identifier must be unique.

The table shows the most pertinent response values for the method. For a complete list of API response parameters, see API Response structure (XML).

Parameter Description
Session

Contains a Session object. For more information, see Session.

This example shows a call with only the required parameters, and the corresponding response.

POST call

  curl --request POST \
  --url https://<YourShopName>.altapaysecure.com/merchant/API/checkoutSession \
  --header 'Authorization: Basic auth' \
  --data terminals[0]='MyTerminal' \
  --data shop_orderid=abc123 \
  --data amount=50 \
  --data currency=EUR \
  --data config[callback_ok]=callback_ok_url \
  --data config[callback_fail]=callback_fail_url \

XML response

<?xml version="1.0"?>
<APIResponse version="20251231">
    <Header>
        <Date>2026-01-05T09:25:19+00:00</Date>
        <Path>API/checkoutSession</Path>
        <ErrorCode>0</ErrorCode>
        <ErrorMessage/>
    </Header>
    <Body>
        <Session>
            <Id>a2179efb-5cfa-4e9f-a952-381eb9480568</Id>
            <Status>CREATED</Status>
        </Session>
    </Body>
</APIResponse>

After you have created checkout session, you can proceed to creating payment request with the session ID using method createPaymentRequest