var myHeaders = new Headers();
myHeaders.append("Content-Type", "application/json;charset=UTF-8");

var raw = "{
\n    \"uuid\": \"af7f6a32-fdb4-4476-a827-bfb76cf8f934\",
\n    \"data\": \"W0JAMzcyNGFmMTM=\"
\n}";

var requestOptions = {
  method: 'POST',
  headers: myHeaders,
  body: raw,
  redirect: 'follow'
};

fetch("https://ismp.crpt.ru/api/v3/auth/cert", requestOptions)
  .then(response => response.text())
  .then(result => console.log(result))
  .catch(error => console.log('error', error));