const options = {method: 'GET'};

fetch('https://swap.ggp.gg/api/{blockchain}/permit/data', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "alreadyApproved": true,
  "alreadyPermit": true,
  "data": {
    "permit": {},
    "typedData": {}
  }
}