api.cs

[Route("api/[controller]")]
[ApiController]
public class DocumentController : ControllerBase
{
    [HttpGet]
    [Route("CreatePdf")]
    public ActionResult<string> CreatePdf(string Html)
    {
        using (TXTextControl.ServerTextControl tx = 
          new TXTextControl.ServerTextControl())
        {
            byte[] data;

            tx.Create();
            // load the Html content
            tx.Load(Html, TXTextControl.StringStreamType.HTMLFormat);
            // save the document as PDF
            tx.Save(out data, TXTextControl.BinaryStreamType.AdobePDF);

            return Convert.ToBase64String(data); // return PDF as base64 string
        }
    }
}