Callback Message Transfer

Request Parameters

A server-to-server callback is sent from the payment gateway to the merchant's website to confirm payments and update the payment status. This data is transmitted as an HTTP POST request to the merchant's website.

Callback Data:

data: Base64-encoded JSON document string
sign: Signature, generated based on the data string

Example:

{
    "data": "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",
    "sign": "68e271b78aa3aa29f1c57f1894248b76"
}

Signature check (PHP example):

hash_hmac('md5', $_POST['data'], $secret_key) === $_POST['sign'])

Where:

secret_key - shop password

JSON Callback Parameters

Parameter	Description
transaction_id	Unique transaction ID in the payment gateway system.
reference	Unique order number in the shop system.
api_key	Shop key (identifier).
amount	Basic payment price.
currency	Currency of the payment. Possible values: EUR, USD.
status	Numeric payment status (see status codes below).
status_name	Status description.
system_amount	Final amount paid by user, including provider commission.
system_currency	Currency used by the payment system.
operation_amount	Actual transaction amount.
commission	Payment system commission value (in system_currency).
payment_system_type	Type of the payment system used.
card_number	Full card number (optional, depends on integration type).
card_pan6	First 6 digits of the card number.
card_pan4	Last 4 digits of the card number.
cardholder_name	Name on the card (optional, depends on integration type).
processing_error_msg	Error message if status = 99.
authorization_code	Payment system authorization code (optional).
pay_token	Recurrent payment token (optional, depends on settings).
params	Custom merchant parameters.
refund_init_type	Refund initiator: 0 = API, 1 = website, 2 = back-office.
refund_reference	Partner’s refund reference ID.

The merchant's website should respond to the callback with the OK string.

The payment gateway will resend the callback if the Merchant website doesn’t respond with the OK string.