What data? The URL is encoded into the QR code.
Like a barcode, the numbers don't need storing externally. The bars *are* the numbers. The QR code image *is* the URL. When you scan the code, your phone decodes the image into the link and then takes you directly there, no third party needed.
What that service might have been doing is linking the QR code to their server, which then looked up your link and forwarded them to it (after collecting the visitor's statistics and cookies). The only real advantage that would provide is allowing you to update the target link after the fact.
Like a barcode, the numbers don't need storing externally. The bars *are* the numbers. The QR code image *is* the URL. When you scan the code, your phone decodes the image into the link and then takes you directly there, no third party needed.
What that service might have been doing is linking the QR code to their server, which then looked up your link and forwarded them to it (after collecting the visitor's statistics and cookies). The only real advantage that would provide is allowing you to update the target link after the fact.