I have done a lot on barcodes on my blog, and I am sure I have mentioned the URL shortener I made that is www.4.gg in the past.
It allows you to provide a URL and gives you a barcode for that in a variety of formats. Some time ago I changed from IEC16022 (DataMatrix) codes to IEC18004 (QR) codes simply because this is a tad like betamax vs VHS, and clearly QR codes have won. Shame, in my view, but they work. It's is even possible to script it to get codes for URLs from automated systems.
I was looking today at some of the stats on the site. It collects very few pieces of data - obviously it has a log of the mapping from an assigned code to a URL, it has to have that, and it records the date/time it was made, and the IP from which it was made and a hit count and latest time of use, and well, that is it.
It was never any attempt to collect data, personal or otherwise. I intended it to be useful, and well, we (A&A) use it for things like barcodes on invoices.
What makes it special is that the barcode is designed to fit the minimal QR code format, so is compact and/or easy to read. For example :-
I checked, and was amazed that there are literally millions of hits on these codes now. It has been working for like 9 years now. We actually have over a 1000 new codes created a day now, which shocked me! When I started some camera phones had QR or data matrix readers, and even the Nokia phone had a bug that did not like a "z" in the code. These days phones have QR code readers in the camera apps, and iPhones just "see" QR codes when taking a picture...
So then comes GDPR, and I am concerned - we collect IP address when codes created and hit counts. Importantly we could collect way more if we wanted to. Some may count as "personal data" though that is questionable. So do I have to worry.
Well, best plan is make this an official free service by A&A and include in GDPR privacy statements. Annoying we have to do this crap in many ways, but let's do the right thing shall we.
BTW, the most popular code is some site that is now a parked domain, over 500k hits and even one today, so someone has put that barcode somewhere massively popular and I know nothing about it. Amazing how a free service I have not even advertised has taken off.
What is especially amusing is Facebook hampering my freedom of speech talking about it!
First time I have ever been accused of spamming... What is amusing is that I could post that screen shot on Facebook and a QR code of my post and the various comments and replies in QR code with no problem. Shows how effective Facebooks policies are in practice. LOL.