curl --request GET \
  --url https://app.flowglad.com/api/v1/customers/{externalId} \
  --header 'Authorization: <api-key>'

{
  "customer": {
    "id": "<string>",
    "createdAt": 0,
    "updatedAt": 0,
    "livemode": true,
    "organizationId": "<string>",
    "email": "<string>",
    "name": "<string>",
    "invoiceNumberBase": "<string>",
    "archived": true,
    "logoURL": "<string>",
    "iconURL": "<string>",
    "domain": "<string>",
    "externalId": "<string>",
    "userId": "<string>",
    "pricingModelId": "<string>",
    "billingAddress": {
      "address": {
        "country": "<string>",
        "name": "<string>",
        "line1": "<string>",
        "line2": "<string>",
        "city": "<string>",
        "state": "<string>",
        "postal_code": "<string>"
      },
      "name": "<string>",
      "firstName": "<string>",
      "lastName": "<string>",
      "email": "[email protected]",
      "phone": "<string>"
    }
  }
}