What is a Synchronous API Call Type?

In a synchronous payment flow, the payment is processed immediately after the API request is made, and the final result such as approved or declined, is returned in the same API response. This type of flow is typically used for card-present transactions or integrated card payments where the customer interacts with the payment device in real time.

Because the response is immediate, the POS system can proceed with the next step in the checkout process such as printing a receipt or finalising the transaction without waiting for any further updates or callbacks.

How Does a Synchronous API Call Type Work?

When a synchronous payment is initiated, the payment request is sent to the payment processor, and the system waits for the transaction to complete before responding. The payment is processed in real time, through a payment terminal, and the final result such as approved, declined or failed, is returned in the same API response. This allows the POS system to immediately proceed based on the outcome, such as confirming the transaction or prompting the user to try another payment method. There is no need for webhook (callback URL), as the entire process happens within a single, continuous flow.

Request

POST

ENDPOINT
/v/1/payment/sync

Response

RESPONSE TYPE	DESCRIPTION
JSON BODY	If the POS is making use of the Synchronous REST API call, the POS will receive a JSON BODY response for a sale request. The POS has the option to also receive a webhook response for the sale request, however this is optional. Please refer to the Webhook section to set up webhooks.