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Fidel uses webhooks to notify your application when relevant events happen in your account. This functionality can be used to receive data from events not triggered by direct API requests or to receive the data in a service that is not responsible for making the API request but needs to consume the response.

Fidel will notify your registered webhook URLs as the event happens. For example, when a customer makes a payment with a linked Mastercard on a participating location, a transaction.auth event is sent in real-time to the specified webhook URL with the transaction object in the request payload.

Creating webhooks

Webhooks can be created in the dashboard's webhooks page or by using the Webhooks API. You can create up to five webhook URLs for the same event in the same Program. Fidel sends the data via HTTP POST in JSON format and will send test or live events depending on your dashboard's environment setting or if you are using test or live API keys.

Fidel only accepts HTTPS URLs for webhooks endpoints. In order to create webhooks and receive event data, your server must be configured to support HTTPS with a valid certificate.

Return a 200 status code
To confirm receipt of a webhook event, your server endpoint should return a 200 HTTP status code. Any other response will be treated as a failure and we retry the request three times over the next hour with exponential back off.


To confirm that received events are being sent from Fidel we recommend verifying webhook signatures. That can be done by using the x-fidel-signature and x-fidel-timestamp HTTP headers. This isn't required, but offers an additional layer of security.

A unique secret key is generated for each webhook. The key is returned in the response's secretKey property if you are using the Webhooks API. You can also copy the key from the dashboard's webhooks page by clicking in the Show Key button next to your webhook endpoint. To verify a webhook request, generate a signature using the same key that Fidel uses and compare that to the value of the x-fidel-signature header:

1. Create a string concatenating the body of the request, the webhook URL and the timestamp value from the x-fidel-timestamp header.
2. Double hash the resulting string using the webhook key with HMAC-SHA256 and encode it in Base-64.
3. Compare the signature you generated with the signature provided in the x-fidel-signature header.

Example Javascript implementation
  fidelHeaders - x-fidel-signature and x-fidel-timestamp headers
  payload - request payload (body)
  secret - webhook secretKey
  url - webhook URL
function isSignatureValid(fidelHeaders, payload, secret, url) {
  function base64Digest(s) {
    return crypto.createHmac('sha256', secret)

  /** You can check how much time has passed since the request has been sent */
  /** timestamp - UTC Unix Timestamp (milliseconds) */
  const timestamp = fidelHeaders['x-fidel-timestamp'];
  const content = JSON.stringify(payload) + url + timestamp;

  const signature = base64Digest(base64Digest(content));
  return fidelHeaders['x-fidel-signature'] === signature;

To prevent replay attacks where a valid payload and its signature is intercepted and re-transmitted, you can use the x-fidel-timestamp header and confirm that the timestamp is not too old. We recommend you validate the requests in a 5 minute gap. In case of retries, a new signature and timestamp are generated for each new request.

Custom headers

Fidel allows you to define custom HTTP headers that are passed in the webhook POST requests sent to you application.

Custom headers can be defined when creating a new webhook in the dashboard or by using the Webhooks API by setting the optional headers object with a key-value pair. You can use the Update Webhook endpoint and submit an empty headers object in order to remove the custom headers from the webhook.

See below an example on how to create a webhook with a custom header using the Create Webhook endpoint:

curl -X POST \ \
  -H 'Content-Type: application/json' \
  -H 'Fidel-Key: sk_test_50ea90b6-2a3b-4a56-814d-1bc592ba4d63' \
  -d '{
    "event": "transaction.auth",
    "url": "",
    "headers": {
      "Custom-Header": "my-custom-header"

Up to 5 custom headers per webhook can be defined and they need to follow strict character validation patterns. You can find more information regarding validation in the Webhooks API reference.

Additionally, the HTTP reserved headers are blacklisted and cannot be used. You can see the full list of blacklisted header names below:




brand.consent event is triggered when the brand consent is approved, in test environment it will trigger immediately after brand creation and in live environment when the Brand User approves the consent request.


  "id": "e44a9220-5b46-42cf-a944-31f0674bf8f8",
  "accountId": "1a269963-de11-4ab5-b82d-638a324ff09e",
  "consent": true,
  "created": "2018-10-19T13:29:40.922Z",
  "live": true,
  "name": "Starbucks",
  "updated": "2018-01-20T13:29:40.922Z"


program.status event is triggered when the program status is updated.


  "id": "f67b7b16-0e3d-457a-811a-cc21dc8448f3",
  "accountId": "77aa1f5f-7152-45dc-8eb1-cb83355e9cf9",
  "active": true,
  "activeDate": "2018-10-28T09: 33: 30.139Z",
  "created": "2018-10-26T17: 10: 02.509Z",
  "live": true,
  "name": "Starbucks Card Linked",
  "syncStats": {
    "status": "updating"
  "updated": "2018-10-30T16: 12: 15.604Z"


There are two webhooks for card linking if you want to receive the response in your server instead of on the client when using the SDK callbacks.

card.linked event is triggered when a card is successfully linked.


  "id": "556f8179-bfdb-4274-852e-ba6e43559590",
  "accountId": "d346d574-d5c2-4a0e-8e02-ffd813fd1a8d",
  "countryCode": "GBR",
  "created": "2018-10-29T17:01:05.013Z",
  "expDate": "2019-10-01T00:00:00.000Z",
  "expMonth": 10,
  "expYear": 2019,
  "firstNumbers": "444400",
  "lastNumbers": "4735",
  "live": false,
  "programId": "cc67a36a-bae5-4b91-80f0-1ba9a0851eb5",
  "scheme": "visa",
  "type": "visa",
  "updated": "2018-10-29T17:01:05.013Z"

card.failed event is triggered when card linking fails. This payload includes the event name and error message.


  "card": {
    "id": "c3730d4d-9915-4c51-831f-14b8aeeb56b7",
    "accountId": "d346c574-d5c2-4a0e-8e02-ffd713fd1a8d",
    "countryCode": "GBR",
    "created": "2018-10-29T17:34:54.693Z",
    "expDate": "2020-10-01T00:00:00.000Z",
    "expMonth": 10,
    "expYear": 2020,
    "firstNumbers": "528245",
    "lastNumbers": "6015",
    "live": true,
    "programId": "ca9885fc-1f31-4120-8cfe-4c28c3b6cfdb",
    "scheme": "mastercard",
    "type": "mastercard",
    "updated": "2018-10-29T17:34:56.380Z"
  "event": "card.failed",
  "message": "Error linking card."


Authorisation transaction events are triggered while the customer is making the payment in-store in real-time. When a customer makes a payment with a linked debit/credit card in an auth-enabled location, a transaction.auth event is triggered and the transaction object sent to your specified URL in real-time.

Clearing events are triggered when the transaction is settled, usually happens 24-48 hours after the payment has been made. Fidel processes clearing transactions triggering the transaction.clearing webhook events daily at 12:00 UTC for Mastercard and multiple times per day for Visa and American Express. Only one transaction is sent per event.

There are two additional transaction webhook events: transaction.auth.qualified and transaction.clearing.qualified. They are triggered when an auth or a clearing transaction is qualified for an offer. The payload for these events includes the offer object with the results of the qualification as you can see in the Offers API documentation.

You can filter transactions from a specific offer by setting the offerId optional property when creating a transaction qualification webhook event. See more information on how to use it on the Create Webhook endpoint reference.


  "id": "7fdfd5d8-9589-402f-8477-4a727ad239a2",
  "accountId": "4ed4b62b-aa4c-43a1-8064-da6d1368e17a",
  "programId": "6e38aa0c-b7ef-46bd-b1bd-c07c648d9cba",
  "datetime": "2019-03-12T19:12:01",
  "created": "2019-03-12T19:12:01.744Z",
  "updated": "2019-03-12T19:12:01.744Z",
  "offer": null,
  "auth": true,
  "cleared": false,
  "amount": 100,
  "currency": "GBP",
  "wallet": null,
  "card": {
    "id": "bc538b71-31c5-4699-840a-6d4a08693314",
    "firstNumbers": "555500",
    "lastNumbers": "5001",
    "scheme": "visa",
    "metadata": {
      "name": "fancy card",
      "id": "card-id"
  "brand": {
    "id": "9d136f2e-df99-4a08-a0a5-3bc1534b7db9",
    "name": "Bob's Cafe",
    "logoURL": null
  "location": {
    "id": "7a916fbd-70a0-462f-8dbc-bd7dbfbea160",
    "address": "2 Soho Square",
    "city": "London",
    "postcode": "W1D3PX",
    "countryCode": "GBR",
    "timezone": "Europe/London",
    "geolocation": {
      "latitude": 51.5152346,
      "longitude": -0.1310718
    "metadata": {
      "id": "your-user-id",
      "name": "username"
  "identifiers": {
    "MID": "12345678",
    "mastercardTransactionSequenceNumber": "0000000000000",
    "mastercardRefNumber": "AABBCCDDE",
    "amexApprovalCode": "AA00BB",
    "visaAuthCode": "000000"

We are working to extend the list of events. If you require any specific event that is not available yet please reach out on our community or email at