QR Codes were developed by Denso Wave Inc. but they have chosen not to exercise the patent. That means you are free to use, generate, decode, print, display QR Codes without any licensing requirements.
This is good news.
The only limitation is that the name itself is a trademark and they require that you include this line of text in any document/webpage that uses the phrase ‘QR Code’
QR Code is registered trademark of DENSO WAVE INCORPORATED.
You can read more about the exact requirements here: