Create Your First Payment

This guide walks you through creating your first payment using Carbn’s payment infrastructure. Before initiating payments, ensure your users have completed onboarding and have active status.

Prerequisites

Before you can create payments, you need:

Active Users: Users must have active status after successful KYC verification
Registered Accounts: Users need registered bank accounts or wallets
API Authentication: Valid API key with payment permissions

Users with under_review, rejected, or incomplete status cannot initiate payments.

Steps to make your first payment:

Before initiating transfers, users need registered destination account (bank accounts or wallets).

curl --location --request POST 'https://api.carbnconnect.com/payment/api/v1/accounts/register' \
--header 'Content-Type: application/json' \
--header 'x-api-key: <api-key>' \
--data-raw '{
  "user_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "account_type": "bank_account",
  "account_details": {
    "account_number": "1234567890",
    "routing_number": "021000021",
    "bank_name": "Example Bank",
    "account_holder_name": "John Doe"
  },
  "currency": "USD"
}'

curl --location --request POST 'https://api.carbnconnect.com/payment/api/v1/wallets/register' \
--header 'Content-Type: application/json' \
--header 'x-api-key: <api-key>' \
--data-raw '{
  "user_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "crypto": "USDC",
    wallet_address: "3BsSG...",
    blockchain: "solana",
  "source_currency": "USD"
}'

Initiate Onramp Transfer

Now that you have registered a destination wallet, you can initiate an onramp transfer (fiat to stablecoins). Carbn Connect supports multiple methods for onramp transfers:

Open Banking Transfer

Open Banking provides better visibility and user experience. The deposit links guide users through the payment flow without leaving your application, giving you full control over the user journey.

Regional Availability: Open Banking is currently available for onramp transfers in US, EU, and UK.

curl --location --request POST 'https://api.carbnconnect.com/payment/api/v1/transfers/onramp' \
--header 'Content-Type: application/json' \
--header 'x-api-key: <api-key>' \
--data-raw '{
  "user_id": "0abad22b-53d3-4473-b1ee-283f4b32e3ad",
  "wallet_id": "34e9819d-2f1c-40a5-9404-a1be8fe34227",
  "open_banking": {
    "amount": 3,
    "redirect_url": "https://www.yourapp.com/payment-success",
    "is_mobile_app": false,
    "country_codes": ["SWE"]
  }
}'

Country Codes Filtering: The country_codes parameter is optional. When not provided, all supported bank countries for the user are available. When provided as an array of ISO 3166-1 alpha-3 country codes (e.g., ["SWE", "NOR"]), only banks from the specified countries will be shown in the payment flow.

{
  "transaction_id": "d5c48677-b85d-4de5-a685-196d0e6596f7",
  "source_currency": "eur",
  "open_banking": {
    "deposit_link": "https://secure.plaid.com/hl/lpps56nr6p98sn9r89341n78s8834q672q",
    "payment_id": "payment-id-production-2308307c-0d61-46d3-9225-50d48f607e36",
    "link_token": "link-production-cf01ae1c-43fa-4e34-896a-23f3389d127d"
  },
  "v_bank": null
}

Open Banking Benefits:

Better Visibility: Full payment tracking and monitoring throughout the process
Enhanced UX: Users never leave your application during payment flow
Real-time Updates: Immediate payment confirmation and status updates
Amount Control: Exact amount validation and processing
Seamless Integration: Embed payment flow directly in your app
Lower Fees: Reduced processing costs compared to traditional methods

Virtual Account Transfer

Virtual Account method serves as a fallback option or for payment methods not supported by Open Banking. It generates unique bank account details that users can transfer money to from any bank. However, it provides limited visibility - you can only monitor once funds are deposited, with no tracking of when users initiate payments or control over transfer amounts.

curl --location --request POST 'https://api.carbnconnect.com/payment/api/v1/transfers/onramp' \
--header 'Content-Type: application/json' \
--header 'x-api-key: <api-key>' \
--data-raw '{
  "user_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "wallet_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
}'

{
  "transaction_id": null,
  "source_currency": "eur",
  "open_banking": null,
  "v_bank": {
    "bic": "MODRIE22XXX",
    "iban": "IE44MODR99035511728566",
    "bank_name": "Modulr Finance, Ireland Branch",
    "payment_rail": "sepa"
  }
}

Virtual Account Limitations:

Limited Visibility: No tracking until funds arrive - you only know when money lands
No Amount Control: Users can send any amount, not necessarily what was requested
Payment Uncertainty: No way to know if/when users actually make the transfer
Delayed Monitoring: Can only monitor after funds are deposited, not during transfer

When to Use Virtual Accounts:

As a fallback when Open Banking is not available
For payment methods not supported by Open Banking
When users prefer traditional bank transfers
For regions outside US/EU/UK where Open Banking isn’t available

QR Payin (PHP)

QR Payin is available exclusively for PHP (Philippine Peso) transactions. This method generates a QR code that users can scan with their mobile banking app to complete the payment. The QR code has an expiration time and must be used before it expires.

Regional Availability: QR Payin is currently available only for PHP currency transactions.Minimum Amount: The minimum transfer amount for QR Payin is 400 PHP.

curl --location --request POST 'https://api.carbnconnect.com/payment/api/v1/transfers/onramp' \
--header 'Content-Type: application/json' \
--header 'x-api-key: <api-key>' \
--data-raw '{
  "user_id": "b8aacdf0-876b-43c1-bbe1-2f2465bbed86",
  "wallet_id": "9a7dc4df-c6a6-4de9-871f-83361b821c29",
  "qr_payin": {
    "amount": 400
  }
}'

{
  "transaction_id": "76e12d55-1a25-457e-9e97-0495162de555",
  "source_currency": "PHP",
  "qr_payin": {
    "qr_code": "00020101021228600011ph.ppmi.p2m0111DCPHPHM1XXX03192147235668383093866050301152044814530360854034005802PH5904test6015MAHAGUN MORPHEU62380011ph.ppmi.p2m0519198581120859644569663048038",
    "expiry_time": "2026-02-10T07:13:58.621Z"
  }
}

QR Payin Benefits:

Convenient: Users can pay by scanning QR code with their mobile banking app
Fast Processing: Payments are processed quickly once scanned
Mobile-Friendly: Ideal for mobile-first payment flows
Secure: Uses standard QR payment protocols

Important: The QR code has an expiration time. Users must complete the payment before the expiry_time. After expiration, a new QR code must be generated.