FYST

Connect H2H Merchant account in Corefy Dashboard

Step 1 - Open connection form

Open FYST in the provider directory and press Connect at FYST Provider Overview page in the New connection section.

Step 2 - Fill in fields and select settings

• Login
• Control key
• Endpoint ID
• Multi currency integration
• Test Mode -> (enable if you are using sandbox credentials)

First request to Corefy API (MIN)

What it does: creates a payment-invoice; card data itself is collected and submitted separately by Corefy's checkout/SDK layer, not as part of this request. Card, Sofort (bank transfer redirect), and BLIK are all supported on this same connection, selected via service.

Payment - MIN

POST /api/payment-invoices

{
  "data": {
    "type": "payment-invoice",
    "attributes": {
      "reference_id": "882f2326-0451-473a-9c43-3c6b1b8997e9",
      "service": "payment_card_eur_hpp",
      "currency": "EUR",
      "amount": 10
    }
  }
}

Payment - MAX

POST /api/payment-invoices

{
  "data": {
    "type": "payment-invoice",
    "attributes": {
      "reference_id": "9da51014-d014-413b-84a9-b79b5ae8b5ec",
      "service": "payment_card_eur_hpp",
      "currency": "EUR",
      "amount": 10,
      "customer": {
        "reference_id": "cus_123",
        "name": "John Doe",
        "email": "john@example.com",
        "phone": "+491234567890",
        "date_of_birth": "1990-01-01",
        "address": {
          "full_address": "Main street 1",
          "country": "DE",
          "region": "Berlin",
          "city": "Berlin",
          "street": "Main street 1",
          "post_code": "10115"
        }
      }
    }
  }
}

Extended request (MAX)

Why add extra fields (typical reasons): - Provide additional customer details for compliance/reconciliation - Positively influence conversion rate - Include optional fields required by your specific flow

Options

• ignore_callback -> optional, boolean - for cascading to work correctly, ignores FYST's asynchronous callback and relies only on an active status request to finalize the payment.
• use_default_browser_info -> optional, boolean - when the customer's real browser data isn't available, falls back to the matching browser-data Constants instead of leaving those fields empty.
• custom_finalization_logic -> optional, boolean - when enabled, a response with status APPROVED is always treated as successful, even if FYST's response also includes an error code or message alongside it; when disabled (default), an error code/message in the response is treated as a failure regardless of the status.

Constants (fallback fields)

Constants are static values that Corefy can send to the provider instead of dynamic data from your API request, when those fields are missing in the request.

Priority (predictable rule): 1. If a value is present in the request -> Corefy uses the request value 2. Else if the constant is set -> Corefy uses the constant 3. Else -> a fixed placeholder value is used (see the important note above) or provider may reject the request, depending on the field

Currently available constants (constant -> Corefy API field)

• ADDRESS -> customer.address.full_address
• CITY -> customer.address.city
• COUNTRY -> customer.address.country
• POST_CODE -> customer.address.post_code
• PHONE -> customer.phone
• EMAIL -> customer.email
• DATE_OF_BIRTH -> customer.date_of_birth
• BROWSER_INFO, BROWSER_TZ_OFFSET, BROWSER_SCREEN_WIDTH, BROWSER_SCREEN_HEIGHT, BROWSER_COLOR_DEPTH, BROWSER_LANGUAGE, BROWSER_JAVA_ENABLED, BROWSER_ACCEPT_HEADER, BROWSER_USER_AGENT, BROWSER_IP -> fallback browser fingerprint data, used only when use_default_browser_info is enabled

Refunds

FYST supports partial refunds, but only one refund per payment (no multiple partial refunds against the same payment).