# Copy of Core API

### Introduction <a href="#introduction" id="introduction"></a>

**Core API** enables communication between your system and Finpay payment gateway system. The payment page and data input is native to the merchant's website/application, without having redirect to a Finpay PG Hosted page. Having the payment form on the merchant page does not compromise the security of the cardholder however, none of the cardholder data will actually be stored on the merchant’s server.

### Transaction Flow <a href="#transaction-flow" id="transaction-flow"></a>

The overall end-to-end payment process in Core API is illustrated in following sequence diagram:

{% @mermaid/diagram content="sequenceDiagram

Customer->>Merchant: 1. Choose Payment Method
opt Push Notif
Customer->>Finpay : Input Customer ID
end
Merchant->>Finpay: 2. Request Core API
Finpay->>Merchant: 3. Response Core API
opt Push Notif
Customer->>Mobile Apps : 4. Continue transaction
Provider->>Finpay : 5. Callback Notification
Finpay->>Merchant : 6. Callback Notification
Merchant->>Customer : 7. Notification
end
opt Jump App / App Link
Merchant->>Mobile Apps : 4. Open Provider Mobile Apps
Customer->>Mobile Apps : 5. Continue transaction
Provider->>Finpay : 6. Callback Notification
Finpay->>Merchant : 7. Callback Notification
Merchant->>Customer : 8. Notification
end
opt Web Checkout
Merchant->>Web Checkout Page : 4. Redirect to Provider Web Checkout Page
Customer->>Web Checkout Page : 5. Continue transaction
Provider->>Finpay : 6. Callback Notification
Finpay->>Merchant : 7. Callback Notification
Merchant->>Customer : 8. Notification
end
opt Pending Payment
Merchant->>Merchant : 4. Show Virtual Account Number / Payment Code
Customer->>Payment Channel : 5. Continue transaction
Payment Channel->>Finpay : 6. Callback Notification
Finpay->>Merchant : 7. Callback Notification
Merchant->>Customer : 8. Notification
end
opt QRIS
Merchant->>Merchant : 4. Show QR Image
Customer->>Mobile Apps : 5. Scan QR & continue transaction
Provider->>Finpay : 6. Callback Notification
Finpay->>Merchant : 7. Callback Notification
Merchant->>Customer : 8. Notification
end" %}


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