Very very nice, but better (for me) if . . . Rated 3 out of 5 stars
After looking at it (real quick), first, very nice idea!! Works very effortlessly. Biggy for me is to be able to save the image for printing in my use case. I did run into a problem with the QRCODE for a paragraph not being readable by my Mbarcode app. But making the selection smaller fixed it. I imagine this was a screen resolution problem that my phone was not able to see the smaller squares of the higher resolution qrcode that was generated. Some way of generating the code in a standard minimum block size might help immediately for this type of situation.
I do have a couple of suggestions for added capabilities.
!.) Provide a method for copying the QRCODE image to the clipboard, or display in a separate page, or??
2.) Provide a mechanism to supply my own QRCODE generator as an option. I looked in the code, and see that this wouldn't be too big a problem to do, but you have the links hardcoded in for each of the existing options. There are a number of possible optional parameters available for making QRCodes that might be nice to add at some point as well.