Send a remittance with fixed debit amount

Summary

Learn how to send a one-time remittance payment by debiting the sender’s account by a specific amount.

A remittance payment is a transfer of money from one person to another, typically across borders or long distances, often involving currency conversion and fees. In this guide, you will learn how to implement a one-time remittance payment feature where your users can specify exactly how much they want to pay, rather than how much the recipient should receive.

This approach is particularly useful for remittance app scenarios where:

• Your users want to pay a fixed amount from their account
• The recipient receives whatever amount remains after fees and currency conversion
• Your users want to avoid the complexity of calculating fees upfront

Scenario

Imagine someone in the US sending money to a family member in Mexico. They want to send exactly $100 US Dollars (USD) from their account, regardless of how much their family member actually receives after fees and exchange rates. This is different from sending money where the sender specifies exactly how much the recipient should receive.

For this guide, you’ll assume the role of a developer building a remittance app. The guide explains how to send a $100 USD payment, where the sender pays exactly $100, and the recipient receives the amount in Mexican Pesos (MXN) after all fees and currency conversion.

Example transaction details:

• Sender pays: $100.00 USD (exact amount)
• Fees: $5.00 USD (5% processing fee)
• Currency conversion: USD to MXN at 17.00 exchange rate
• Recipient receives: $1,615.00 MXN (($100 - $5) × 17.00)

The three parties involved in this scenario are:

• Developer: you, the person building the remittance app
• Sender: the person using your app to send money in USD
• Recipient: the person receiving the money in MXN

Remember, Open Payments doesn’t execute payments or touch money in any way. It’s used to issue payment instructions before any money movement occurs. An example of a payment instruction is, “debit exactly $100 from the sender’s account and send it to the recipient’s account, where they will receive $1,615.00 MXN after $5 in fees and USD to MXN conversion.”

Endpoints

• GET Get Wallet Address
• POST Grant Request
• POST Create Incoming Payment
• POST Create a Quote
• POST Create an Outgoing Payment

Steps

1. Get wallet address information

When your user initiates a payment through your remittance app, you need to get wallet address information for both the sender and the recipient.

Let’s assume your user has already provided their own wallet address when they signed up to use your app. Let’s also assume the sender entered the recipient’s wallet address into your app’s payment form when initiating the payment.

Call the GET Get Wallet Address API for each address.

TypeScript/JavaScript

const senderWalletAddress = await client.walletAddress.get({
  url: 'https://cloudninebank.example.com/sender'
})
const recipientWalletAddress = await client.walletAddress.get({
  url: 'https://happylifebank.example.com/recipient'
})

Example response

The following shows an example response from the sender’s wallet provider. A similar response will be returned from the recipient’s wallet provider.

{
  "id": "https://cloudninebank.example.com/sender",
  "assetCode": "USD",
  "assetScale": 2,
  "authServer": "https://auth.cloudninebank.example.com/",
  "resourceServer": "https://cloudninebank.example.com/op"
}

2. Request an incoming payment grant

Use the recipient’s authServer details, received in the previous step, to call the POST Grant Request API.

This call obtains an access token that allows your app to request that an incoming payment resource be created on the recipient’s wallet account.

TypeScript/JavaScript

const recipientIncomingPaymentGrant = await client.grant.request(
  {
    url: recipientWalletAddress.authServer
  },
  {
    access_token: {
      access: [
        {
          type: "incoming-payment",
          actions: ["read", "create"],
        },
      ],
    },
  },
);

Example response

The following shows an example response from the recipient’s wallet provider.

{
  "access_token": {
    "value": "...", // access token value for incoming payment grant
    "manage": "https://happylifebank.example.com/token/{...}", // management uri for access token
    "access": [
      {
        "type": "incoming-payment",
        "actions": ["create", "read"]
      }
    ]
  },
  "continue": {
    "access_token": {
      "value": "..." // access token for continuing the request
    },
    "uri": "https://happylifebank.example.com/continue/{...}" // continuation request uri
  }
}

3. Request the creation of an incoming payment resource

Use the access token returned in the previous response to call the POST Create Incoming Payment API.

This call requests an incoming payment resource be created on the recipient’s wallet account.

TypeScript/JavaScript

const recipientIncomingPayment = await client.incomingPayment.create(
  {
    url: recipientWalletAddress.resourceServer,
    accessToken: recipientIncomingPaymentGrant.access_token.value
  },
  {
    walletAddress: recipientWalletAddress.id
  },
)

Example response

The following shows an example response from the recipient’s wallet provider.

{
  "id": "https://happylifebank.example.com/incoming-payments/{...}",
  "walletAddress": "https://happylifebank.example.com/recipient",
  "receivedAmount": {
    "value": "0",
    "assetCode": "USD",
    "assetScale": 2
  },
  "completed": false,
  "createdAt": "2025-03-12T23:20:50.52Z",
  "methods": [
    {
      "type": "ilp",
      "ilpAddress": "...",
      "sharedSecret": "..."
    }
  ]
}

4. Request a quote grant

Use the sender’s authServer details, received in Step 1, to call the POST Grant Request API.

This call obtains an access token that allows your app to request that a quote resource be created on the sender’s wallet account.

TypeScript/JavaScript

const senderQuoteGrant = await client.grant.request(
  {
    url: senderWalletAddress.authServer
  },
  {
    access_token: {
      access: [
        {
          type: 'quote',
          actions: ['create', 'read']
        }
      ]
    }
  }
)

Example response

{
  "access_token": {
    "value": "...", // access token value for quote grant
    "manage": "https://cloudninebank.example.com/token/{...}", // management uri for access token
    "access": [
      {
        "type": "quote",
        "actions": ["create", "read"]
      }
    ]
  },
  "continue": {
    "access_token": {
      "value": "..." // access token for continuing the request
    },
    "uri": "https://auth.cloudninebank.example.com/continue/{...}" // continuation request uri
  }
}

5. Request the creation of a quote resource

Use the access token, received in the previous step, to call the POST Create Quote API.

This call requests that a quote resource be created on the sender’s wallet account. The request must contain the receiver, which is the recipient’s incoming payment id, along with the debitAmount, which is the exact amount the sender wants to pay.

The debitAmount specifies that the sender will pay exactly $100 USD, and the recipient will receive whatever amount remains after all fees and currency conversion.

TypeScript/JavaScript

const senderQuote = await client.quote.create(
  {
    url: senderWalletAddress.resourceServer,
    accessToken: senderQuoteGrant.access_token.value
  },
  {
    method: 'ilp',
    walletAddress: senderWalletAddress.id,
    receiver: recipientIncomingPayment.id,
    debitAmount: {
      value: '10000', // $100.00 USD
      assetCode: 'USD',
      assetScale: 2
    }
  }
)

The response returns a receiveAmount, a debitAmount, and other required information.

• debitAmount - The amount the sender must pay (exactly $100.00 USD in our example).
• receiveAmount - The amount the recipient will actually receive ($1,650.00 MXN in our example) after fees and currency conversion.

Example response

The following shows an example response from the sender’s wallet provider.

{
  "id": "https://cloudninebank.example.com/quotes/{...}", // url identifying the quote
  "walletAddress": "https://cloudninebank.example.com/sender",
  "receiver": "https://happylifebank.example.com/incoming-payments/{...}", // url of the incoming payment the quote is created for
  "debitAmount": {
    "value": "10000", // Sender pays exactly $100.00 USD
    "assetCode": "USD",
    "assetScale": 2
  },
  "receiveAmount": {
    "value": "161500", // Recipient receives 1,615.00 MXN after fees and currency conversion
    "assetCode": "MXN",
    "assetScale": 2
  },
  "method": "ilp",
  "createdAt": "2025-03-12T23:22:51.50Z"
}

6. Request an interactive outgoing payment grant

Use the sender’s authServer information received in Step 1 to call the POST Grant Request API.

This call obtains an access token that allows your app to request that an outgoing payment resource be created on the sender’s wallet account.

Note

Outgoing payments require an interactive grant. This type of grant will obtain the customer’s consent before an outgoing payment is made against their wallet account. You can find more information in the Open Payments flow and identity providers pages.

TypeScript/JavaScript

const pendingSenderOutgoingPaymentGrant = await client.grant.request(
  {
    url: senderWalletAddress.authServer
  },
  {
    access_token: {
      access: [
        {
          identifier: senderWalletAddress.id,
          type: 'outgoing-payment',
          actions: ['read', 'create'],
          limits: {
            debitAmount: {
              assetCode: 'USD',
              assetScale: 2,
              value: quote.debitAmount.value, // 10000
            }
          }
        }
      ]
    },
    interact: {
      start: ['redirect'],
      finish: {
        method: 'redirect',
        uri: 'https://myapp.example.com/finish/{...}', // where to redirect your user after they've completed the interaction
        nonce: NONCE
      }
    }
  }
)

Example response

{
  "interact": {
    "redirect": "https://auth.cloudninebank.example.com/{...}", // uri to redirect the sender to, to begin interaction
    "finish": "..." // unique key to secure the callback
  },
  "continue": {
    "access_token": {
      "value": "..." // access token for continuing the outgoing payment grant request
    },
    "uri": "https://auth.cloudninebank.example.com/continue/{...}", // uri for continuing the outgoing payment grant request
    "wait": 30
  }
}

7. Start interaction with the user

Once the client receives the authorization server’s response, it must send the user to the interact.redirect URI contained in the response. This starts the interaction flow.

The response also includes a continue object, which is essential for managing the interaction and obtaining explicit user consent for outgoing payment grants. The continue object contains an access token and a URI that the client will use to finalize the grant request after the user has completed their interaction with the identity provider (IdP). This ensures that the client can securely obtain the necessary permissions to proceed with the payment process.

8. Finish interaction with the user

The user interacts with the authorization server through the server’s interface and approves or denies the grant.

Provided the user approves the grant, the authorization server:

• Sends the user to the finish.uri provided in the interactive outgoing payment grant request. The means by which the server sends the user to the URI is out of scope, but common options include redirecting the user from a web page and launching the system browser with the target URI.
• Secures the redirect by adding a unique hash, allowing your client to validate the finish call, and an interaction reference as query parameters to the URI.

9. Request a grant continuation

In our example, we’re assuming the IdP your user interacted with has a user interface. When the interaction completes, your user returns to your app. Now your app can make a continuation request for the outgoing payment grant.

Note

In a scenario where a user interface isn’t available, consider implementing a polling mechanism to check for the completion of the interaction.

Call the POST Grant Continuation Request API. This call requests an access token that allows your app to request that an outgoing payment resource be created on the sender’s wallet account.

Issue the request to the continue.uri provided in the initial outgoing payment grant response (Step 6).

Include the interact_ref returned in the redirect URI’s query parameters.

TypeScript/JavaScript

const senderOutgoingPaymentGrant = await client.grant.continue(
  {
    url: pendingSenderOutgoingPaymentGrant.continue.uri,
    accessToken: pendingSenderOutgoingPaymentGrant.continue.access_token.value
  },
  {
    interact_ref: interactRef
  }
)

Example response

{
  "access_token": {
    "value": "...", // final access token required before creating outgoing payments
    "manage": "https://auth.cloudninebank.example.com/token/{...}", // management uri for access token
    "access": [
      {
        "type": "outgoing-payment",
        "actions": ["create", "read"],
        "identifier": "https://cloudninebank.example.com/sender",
        "limits": {
          "receiver": "https://happylifebank.example.com/incoming-payments/{...}" // url of the incoming payment that's being paid
        }
      }
    ]
  },
  "continue": {
    "access_token": {
      "value": "..." // access token for continuing the request
    },
    "uri": "https://auth.cloudninebank.example.com/continue/{...}" // continuation request uri
  }
}

10. Request the creation of an outgoing payment resource

Recall that the Create Quote API response (Step 5) included a debitAmount and a receiveAmount. The response also included an id which is a URL to identify the quote.

Because the quote contains debit and receive amounts, we won’t specify any other amounts when setting up the outgoing payment. Instead, we will specify a quoteId.

Use the access token returned in Step 9 to call the POST Create Outgoing Payment API. Include the quoteId in the request.

TypeScript/JavaScript

const senderOutgoingPayment = await client.outgoingPayment.create(
  {
    url: senderWalletAddress.resourceServer,
    accessToken: senderOutgoingPaymentGrant.access_token.value
  },
  {
    walletAddress: senderWalletAddress.id,
    quoteId: senderQuote.id
  }
)

Example response

The following shows an example response when an outgoing payment resource is created on the sender’s account.

{
  "id": "https://cloudninebank.example.com/outgoing-payments/{...}", // url identifying the outgoing payment
  "walletAddress": "https://cloudninebank.example.com/sender",
  "receiver": "https://happylifebank.example.com/incoming-payments/{...}", // url of the incoming payment being paid
  "debitAmount": {
    "value": "10000", // Sender pays exactly $100.00 USD
    "assetCode": "USD",
    "assetScale": 2
  },
  "receiveAmount": {
    "value": "161500", // Recipient receives 1,615.00 MXN after fees and currency conversion
    "assetCode": "MXN",
    "assetScale": 2
  },
  "sentAmount": {
    "value": "0",
    "assetCode": "USD",
    "assetScale": 2
  },
  "createdAt": "2022-03-12T23:20:54.52Z"
}