const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

fetch('https://api.paddle.com/customers/{customer_id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "data": {
    "id": "ctm_01hrffh7gvp29kc7xahm8wddwa",
    "status": "active",
    "custom_data": null,
    "name": "Sam Miller",
    "email": "[email protected]",
    "marketing_consent": false,
    "locale": "en",
    "created_at": "2024-03-08T16:49:53.691Z",
    "updated_at": "2024-04-11T16:03:57.924146Z",
    "import_meta": null
  },
  "meta": {
    "request_id": "aa0009cb-18f7-4538-b1cd-ad29d91cfaa7"
  }
}