Add a watermark to a PDF using C# with scConverter

add-watermark-to-pdf.cs

//scConverter Sample Code
//Read more about scConverter online: 
//		https://www.softwarecompanions.com/scconverterdll.html
//		https://www.softwarecompanions.com/scconverter-c-sharp.html

{
   scConverterLib.Converter myconverter = new scConverterLib.Converter();
   if (myconverter != null)
   {
      myconverter.SetSerialNumber("Your Serial Number");
      //Add watermark with black text, rotated 45 degrees and with 30% opacity.
      //The watermark will be added to all pages when "ALL" is used.
      //Use "1" if you want the watermark added to the first page only.
      myconverter.PDFAddWatermark( "input.pdf", "output.pdf", "ALL", "Confidential", 45, 30, 0x000000 );  
   }
}

Read more about scConverter online.