Below content is similar for Atomic as well as AX2


Webhooks allow APEXX to push transaction updates to the merchant application as they become available. In the normal course of events, the merchant application sends out API requests to which APEXX responds in turn. If the merchant requires a notification for an event such as a settlement or chargeback, the communication will need to be initiated by APEXX instead. Webhooks are asynchronous, which means that API messages are pushed by APEXX to the merchant application in response to some kind of external trigger (e.g. a reconciliation file update), rather than as a response to a transaction request originating from the merchant. 


The merchant application will need to provide a URL that the webhook can deliver the data to and which is accessible to APEXX servers.


The full URL for the webhook endpoint can either be configured against a specific account by your APEXX Implementation Consultant, or sent dynamically in the webhook_transaction_update field of the transaction request. To ensure that webhook notifications are only received by authorised domains, the top level domain received in the transaction request must match one of the the top level domains configured on the APEXX account used for the transaction. If a full webhook transaction update URL are supplied in both the account configuration in APEXX and in the API request, then the URL provided in the request will override that in the account configuration, as long as the top level domains match.


The merchant application will need to processes the incoming webhook events and return a response message to APEXX. If APEXX does not receive a message indicating that the event update was successfully received, it will attempt to resend the update at a later point in time. After 10 failed delivery attempts, APEXX will send a delivery failure notification to the merchant. 


Webhooks will be sent in the event of a transaction update, e.g. 

  • Authorisation
  • Capture / Settlement
  • Sale (Authorisation + Capture)
  • Void (only valid on an Authorisation)
  • Refund
  • Chargeback (where reconciliation files are used) 

Please note that the chargeback notification processes are handled differently from acquirer to acquirer. 


Please refer to the transaction webhooks section in the APEXX API specification for details. If you do not see a data point you require, please raise this with your Implementation Manager.


What does "Webhook Failed Transactions Update" mean?

Using Reconciliation Files for Post-Authorisation Updates

How does APEXX notify merchants of transaction failures?

For which events will APEXX send webhook notificatio?