I suggest you use Itextsharp. If you are using asp.net c#, this code works for you. Runs in the server side though. You can just put the html inside a panel to make it readable in the server.
/// import these namespaces
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
using iTextSharp.text.html.simpleparser;
using System.Web.Services;
using System.Text;
/// Call this method whenever you need to convert
/// the html content inside the panel which runs in the server side.
[WebMethod]
public void ConvertHtmlStringToPDF()
{
StringBuilder sb = new StringBuilder();
StringWriter tw = new StringWriter(sb);
HtmlTextWriter hw = new HtmlTextWriter(tw);
pnlPDF.RenderControl(hw);
string htmlDisplayText = sb.ToString();
Document document = new Document();
MemoryStream ms = new MemoryStream();
PdfWriter writer = PdfWriter.GetInstance(document, ms);
StringReader se = new StringReader(htmlDisplayText);
HTMLWorker obj = new HTMLWorker(document);
document.Open();
obj.Parse(se);
// step 5: we close the document
document.Close();
Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=report.pdf");
Response.ContentType = "application/pdf";
Response.Buffer = true;
Response.OutputStream.Write(ms.GetBuffer(), 0, ms.GetBuffer().Length);
Response.OutputStream.Flush();
Response.End();
}