Base64 encoded to pdf in Google chrome?

You can use a Blob URL to represent the file.

fetch(<data URI>)
.then(response => response.blob())
.then(blob => {
  // do stuff with `Blob URL`
  const blobURL = URL.createObjectURL(blob);
});

See Creating a Blob from a base64 string in JavaScript, also Base64 PDF in new tab shows Blank Page before Refresh.

window.open("data:application/octet-stream;base64," + response)