If you mainly work on a Linux PC and don’t have a smartphone handy to scan a possible QRCode, I have what you need.
It’s a small tool called QRscan and which allows the choice to use the webcam of your PC to scan a QRCode on paper for example. Qrscan is also able to export this image in a whole bunch of formats like .jpg, .png or even export it in ASCII format.
And if you don’t have a webcam or if you get the QR Code directly from a website, you can call qrscan with the path to the image of your choice like this:
./qrscan --qr test.png
In short, it helps out if you don’t have a smartphone at hand. QrScan is also available on Windows and macOS, but I couldn’t get it to work on macOS.
Thanks to Baptiste for sharing.