const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    front_image_url: 'https://cdn.thanks.io/letter-backgrounds/bg0.png',
    message: 'Hey %FIRST_NAME%!,\n\nTHANK YOU for allowing us the opportunity to HELP you with your plan!',
    recipients: [
      {
        name: 'Current Resident',
        address: '123 Main Street',
        city: 'Fake City',
        province: 'NY',
        postal_code: '55555',
        country: 'US',
        custom1: 'Example Custom 1',
        custom2: 'Example Custom 2',
        custom3: 'Example Custom 3',
        custom4: 'Example Custom 4'
      },
      {
        name: 'Jane Doe',
        address: '456 Another St',
        city: 'Fake City',
        province: 'NY',
        postal_code: '55555',
        country: 'US'
      }
    ]
  })
};

fetch('https://api.thanks.io/api/v2/estimate/windowedletter', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

curl --request POST \
  --url https://api.thanks.io/api/v2/estimate/windowedletter \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "front_image_url": "https://cdn.thanks.io/letter-backgrounds/bg0.png",
  "message": "Hey %FIRST_NAME%!,\n\nTHANK YOU for allowing us the opportunity to HELP you with your plan!",
  "recipients": [
    {
      "name": "Current Resident",
      "address": "123 Main Street",
      "city": "Fake City",
      "province": "NY",
      "postal_code": "55555",
      "country": "US",
      "custom1": "Example Custom 1",
      "custom2": "Example Custom 2",
      "custom3": "Example Custom 3",
      "custom4": "Example Custom 4"
    },
    {
      "name": "Jane Doe",
      "address": "456 Another St",
      "city": "Fake City",
      "province": "NY",
      "postal_code": "55555",
      "country": "US"
    }
  ]
}
'

import requests

url = "https://api.thanks.io/api/v2/estimate/windowedletter"

payload = {
    "front_image_url": "https://cdn.thanks.io/letter-backgrounds/bg0.png",
    "message": "Hey %FIRST_NAME%!,

THANK YOU for allowing us the opportunity to HELP you with your plan!",
    "recipients": [
        {
            "name": "Current Resident",
            "address": "123 Main Street",
            "city": "Fake City",
            "province": "NY",
            "postal_code": "55555",
            "country": "US",
            "custom1": "Example Custom 1",
            "custom2": "Example Custom 2",
            "custom3": "Example Custom 3",
            "custom4": "Example Custom 4"
        },
        {
            "name": "Jane Doe",
            "address": "456 Another St",
            "city": "Fake City",
            "province": "NY",
            "postal_code": "55555",
            "country": "US"
        }
    ]
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

{
  "message": "OK",
  "data": {
    "type": "letter",
    "size": null,
    "total_recipients": 2,
    "recipients": {
      "united_states": 2,
      "international": 0
    },
    "pending_email_lookups": 0,
    "costs_in_cents": {
      "united_states": 236,
      "international": 0,
      "additional_pages": 0,
      "giftcard_face_value": 0,
      "grand_total": 236
    },
    "total_cost_in_cents": 236,
    "total_cost": "$2.36",
    "current_balance_in_cents": 5000,
    "covered_by_balance": true,
    "test_mode": false,
    "notes": []
  }
}

{
  "message": "Sub Account ID does not exist"
}

{
  "message": "Unauthorized"
}

{
  "status": "API access has been temporarily disabled due to repeated payment failures. Please update your payment method.",
  "message": "API access has been temporarily disabled due to repeated payment failures. Please update your payment method.",
  "code": "api_disabled_payment_failures"
}