Use this thread to discuss the entry Free downloadable QR matrix barcode at the InterNACHI Blog
I just do not know why QR code is so popular. As for the data density and ECL, other 2D barcode like DATA matrix and PDF417 is also good.
Thank you for your recommendation for this free QR Code barcode generator. But there is no tutorial like this free user guide for QR Code generation that I have ever googled.