QR codes are 2D barcodes that have had a mixed success with usability, from nearly ignored (see the Tumblr mocking this), to partially successful (Path add friend UI), to invisibly useful (Snapchat add friend UI). See also examples of profile pictures with indieweb QR codes like and http://research.swtch.com/qr/show/a32975b9627fa8bc
Opaqueness Encourages Domain Squatting
Since QR codes are opaque to the user in terms of what URL is being navigated to, there is more incentive for nefarious domain squatters to take over expired domains that QR codes point to, e.g.:
- 2015-06-19 Heinz QR porn code too saucy for ketchup customer
Heinz has apologised after a QR code on a bottle of tomato ketchup directed people to a pornography website […] the registration of the URL had lapsed because the related promotion had ended. The site is no longer live.
Graham Cluley, an online security expert, said: "QR codes can point to anywhere on the web. The problem is that humans don't have a clue where they're going to be taken because their brain can't read a QR code, like they can a regular URL.
"It seems [Heinz] failed to renew their registration of the domain name, so it slipped out of their hands and was snatched up by an opportunistic porn site.
Generating QR codes
In a post describing the usefulness of QR codes in certain circumstances, Jeremy Keith mentions the Google Chart API, an open API to create QR codes - along with the concern that it may be shut down at any time.
For self-hosting, the open source PHP library PHP QR Code can be used to generate QR codes locally. Sebastian Greger uses it to include QR codes of URLs in the print view of his content, in order to enable easy interaction for readers of the printed version (code snippet)