API Status: Affected


Fidel API provides a developer-friendly, secure and reliable API for businesses to link payment cards with mobile and web applications. Through a single API, developers can securely access data from the three major card networks and build their applications on top of the powerful payments infrastructure.

When a consumer makes a purchase at a participating store with a linked card, Fidel API spots that transaction and sends it to your server in real-time through webhooks. 💳⚡️

Fidel API runs on top of global payment networks, so it doesn’t require changes to existing merchant infrastructures. No need for new software, POS integrations, staff training or new cards. All the PCI compliance requirements are managed by us so you don’t have to.

Currently, the API is available in the United States, UK, Ireland, Canada, Sweden and UAE. Japan is currently in beta stage. Read the full list of available locations for the Select Transactions API and for the Transaction Stream API on the product pages. We work continuously to add support for other countries and networks. If you would like to deploy card-linked applications in other countries please contact us.

You can see an example implementation for integrating the Fidel APIs and Web SDK in our sample application on GitHub.

Check out the API Reference to see all available requests, code examples and response payloads.

Card Linking

The iOS, Android, React Native and Web SDKs provide you a secure UI to collect your user’s card details securely on the web or mobile.

By using Fidel API SDKs, card details are sent directly to Fidel API through a secure connection without exposing your servers to sensitive information taking care of all PCI compliance requirements. Our Card-Linking tutorial explains in detail all the steps required to build a card-linking feature into your application using the Fidel API SDKs.

Your apps will receive an id back that identifies the card in each transaction.

Use one of our test card numbers (for example 4444000000004004) and enter an expiry date in the future.

Web SDK integration script


  data-company-name="Your Company"
  data-title="Link Card"
  data-subtitle="Earn 1 point for every £1 spent online or in-store"
  data-delete-instructions="tapping remove in your settings page."
  data-button-title="Link Card"

Check the Web SDK documentation section for more information about all available parameters, customization options, and the metadata nested object.

Transaction Life Cycle

To understand how the Transaction Select API works and the data it provides to you, it’s important to understand the authorization processes and fund movements that happen when a cardholder makes a purchase.

Authorization, clearing

When a cardholder uses a credit or debit card to make a purchase, the funds are not immediately transferred to the merchant’s account. There are two important events that need to happen for the funds to be transferred: authorization and clearing. Here’s how these events occur:

  1. When the cardholder initiates the transaction, their bank (issuing bank, issuer) needs to authorize it. For this, the authorization request must travel from the merchant through the merchant’s bank (acquirer) and through the card network to the issuing bank.
  2. If the cardholder has the necessary funds, the issuing bank sends back on the same path the authorization response containing the authorization code (auth code), which means that the cardholder can make the purchase. At this point, the payment amount is still on the cardholder’s account. However, the merchant can safely provide the purchased goods or services, as the transaction was authorized. Usually, the merchant places an authorization hold on the cardholder’s account for the authorized amount of the sale.
  3. The next step is the clearing request, which initiates the administrative process of the payment. Typically, clearing occurs at the end of the day, when the acquirer bank collects all the transaction information (amounts, auth codes, etc.) from all payment endpoints of the merchant. Then, on its own processing schedule, the acquirer starts processing the payments with the respective issuing banks.
  4. The issuing bank sends back the clearing response, and the funds are moved to the merchant’s account. Note that at Fidel API both cleared and settled transactions are referred to as cleared transactions.

Where does Fidel API enter the picture?

As we saw, all the transaction events go through the card networks. This is where Fidel API comes into play.

When a cardholder links a card to a Fidel API program, Fidel API verifies the card with the associated card network and creates a token to represent that card, thereby not storing sensitive information about the cardholder or card itself. Using this token-based identification, the card network starts sending the transactions made on that card to Fidel API.

You can then retrieve the collected data using the Transaction Select API. You can also register webhooks to be notified about the card’s transaction events (new authorization, clearing, etc.).