# Receiving information about online payment transactions

# THE TEXT BELOW PRESENTS IPN V1, WHICH WILL BE REMOVED ON FEBRUARY 1, 2026. SEE IPN V2:
https://docs.simpay.pl/en/notifications/payment

# Signature

## Calculating the signature when receiving a notification
We generate the signature by combining all the parameters received (except for the signature) to the API in the order from the table above, separating them with a | separator and adding at the end the key available in the customer panel in the service. 
Hashing must be done using sha256. 
Example for a paid transaction using the declared currency: 


Example for a paid transaction using a different currency than declared: 


The notification is sent using the  method and requires you to respond in the body with  and Http Code .


Endpoint: POST paymentTransactionNotification
Version: 1.0.0

## Request fields (application/json):

  - `id` (string, required)
    Transaction ID

  - `service_id` (string, required)
    Service ID

  - `status` (string, required)
    Transaction status
    Enum: "transaction_new", "transaction_confirmed", "transaction_generated", "transaction_paid", "transaction_failure", "transaction_expired", "transaction_canceled", "transaction_refunded"

  - `amount` (object, required)
    Billing object
    Example: {"value":10,"currency":"PLN","commission":9.9}

  - `amount.value` (number, required)
    Transaction amount (in paid currency)
    Example: 10

  - `amount.currency` (string, required)
    Transaction currency paid by the buyer
    Example: "PLN"

  - `amount.commission` (number, required)
    SimPay's commission amount (in PLN or EUR)
    Example: 9.9

  - `control` (string)
    Field for use by the partner
    Example: "88643ada8857f25a1f391395f922f7db"

  - `channel` (string, required)
    Payment channel
    Example: "blik"

  - `environment` (string, required)
    Enum: "production", "test"

  - `originalAmount` (object)
    Information about the original currency and amount. Object sent only when the payer changed the currency on the payment gateway.

  - `originalAmount.value` (number, required)
    Transaction amount in the currency that was sent when generating.

  - `originalAmount.currency` (string, required)
    Transaction currency that was sent when generating

  - `originalAmount.rate` (number, required)
    Currency exchange rate according to NBP exchange rates from the transaction generation period.

  - `signature` (string, required)
    Notification signature. Signature calculation shown above.
The partner is obliged to verify the signature upon receiving the notification, you can also make a request to the endpoint [Retrieving transaction details](#tag/Payment/operation/paymentGetTransaction)
    Example: "a3116cf4f1e960223c2cc3088bf387278b6675255209bdeaf96a2f316a2fadc1"