curl --request POST \
  --url https://api.anchorage-staging.com/v2/subaccounts/{subaccountId}/fiat/withdrawals \
  --header 'Api-Access-Key: <api-key>' \
  --header 'Api-Signature: <api-signature>' \
  --header 'Api-Timestamp: <api-timestamp>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "asset": {
    "assetType": "USD",
    "amount": "10.01"
  },
  "customerDetails": {
    "beneficiary": {
      "name": "John Doe",
      "accountNumber": "123",
      "address": {
        "address": "123 Main Street",
        "city": "Windsor",
        "state": "Iowa",
        "zipcode": "12312"
      }
    },
    "financialInstitution": {
      "address": {
        "address": "123",
        "address2": "123",
        "city": "123",
        "zipcode": "123",
        "state": "123"
      },
      "name": "name",
      "id": "123",
      "code": "ABA"
    },
    "memo": "12312312"
  }
}
'

import requests

url = "https://api.anchorage-staging.com/v2/subaccounts/{subaccountId}/fiat/withdrawals"

payload = {
    "asset": {
        "assetType": "USD",
        "amount": "10.01"
    },
    "customerDetails": {
        "beneficiary": {
            "name": "John Doe",
            "accountNumber": "123",
            "address": {
                "address": "123 Main Street",
                "city": "Windsor",
                "state": "Iowa",
                "zipcode": "12312"
            }
        },
        "financialInstitution": {
            "address": {
                "address": "123",
                "address2": "123",
                "city": "123",
                "zipcode": "123",
                "state": "123"
            },
            "name": "name",
            "id": "123",
            "code": "ABA"
        },
        "memo": "12312312"
    }
}
headers = {
    "Api-Signature": "<api-signature>",
    "Api-Timestamp": "<api-timestamp>",
    "Api-Access-Key": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'Api-Signature': '<api-signature>',
    'Api-Timestamp': '<api-timestamp>',
    'Api-Access-Key': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    asset: {assetType: 'USD', amount: '10.01'},
    customerDetails: {
      beneficiary: {
        name: 'John Doe',
        accountNumber: '123',
        address: {address: '123 Main Street', city: 'Windsor', state: 'Iowa', zipcode: '12312'}
      },
      financialInstitution: {
        address: {address: '123', address2: '123', city: '123', zipcode: '123', state: '123'},
        name: 'name',
        id: '123',
        code: 'ABA'
      },
      memo: '12312312'
    }
  })
};

fetch('https://api.anchorage-staging.com/v2/subaccounts/{subaccountId}/fiat/withdrawals', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "data": {
    "transactionId": "c4c4652f-0c07-472c-a7f8-955fbe07775d"
  }
}

{
  "message": "Missing required field 'amount'."
}

{
  "message": "Missing required field 'amount'."
}

{
  "message": "Missing required field 'amount'."
}

{
  "message": "Missing required field 'amount'."
}

{
  "message": "Missing required field 'amount'."
}