I am trying to post some data on a backend server. but when i submit the data i got an error following below: Fetch at 'X' from origin 'localhost:8080' has been blocked by cors. No Access-Control-Allow origin in the header.

Though I have access-control-allow origin on header. The code is given below:

fetch(url, {
  mode: "cors",
  method: "POST",
  headers: {
    "Access-Control-Allow-Origin": "http://localhost:8080",
    "Access-Control-Allow-Credentials": "true",
    "Content-Type": "application/json",
    "API-Key": "xxxxxxxxxxxxxx",
    Accept: "application/json",
  },
  body: JSON.stringify(data),
})
  .then((response) => response.json())
  .then((data) => {
    console.log("Success:", data);
  })
  .catch((error) => {
    console.error("Error:", error);
  });

I have tried no-cors policy but that server doesn't accept no-cors request.