const options = {method: 'GET', headers: {Authorization: 'Basic <encoded-value>'}};

fetch('https://api.opereit.ai/v1/ping', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "status": "ok"
}

{
  "statusCode": 401,
  "statusReasonCode": "AUTHENTICATION_REQUIRED",
  "error": "Authentication required"
}

{
  "statusCode": 500,
  "statusReasonCode": "INTERNAL_ERROR",
  "error": "Internal server error"
}