post.cs

[HttpPost]
public IActionResult CreatePDF([FromBody] TransferDocument document) {

  // create a ServerTextControl
  using (TXTextControl.ServerTextControl tx = new TXTextControl.ServerTextControl()) {

    tx.Create();
    tx.Load(Convert.FromBase64String(document.Document),
      TXTextControl.BinaryStreamType.InternalUnicodeFormat);

    byte[] bPDF;

    tx.Save(out bPDF, TXTextControl.BinaryStreamType.AdobePDF);
 
    return Ok(bPDF);
    
  }
}