- https://hackaday.com/2011/08/11/how-to-put-your-logo-in-a-qr-code/
- https://hackaday.com/2013/09/28/making-qr-codes-in-google-docs/
- http://phpqrcode.sourceforge.net/
- http://zxing.appspot.com/generator
- https://www.qrstuff.com/
- http://qrcode.meetheed.com/
- https://www.qrcode-monkey.com/
- https://www.qrlicious.com/
- https://shop.spreadshirt.es/qrcode/