From the update: "Why are QR Codes with capital letters smaller than QR codes with lower-case letters?" https://shkspr.mobi/blog/2025/02/why-are-qr-codes-with-capit... (https://news.ycombinator.com/item?id=43149077)

> (besides micro QR codes)

In case anyone else is interested: https://en.wikipedia.org/wiki/Rectangular_Micro_QR_Code

I saw similar engraved and then inked onto wooden boards at a restaurant, sadly, despite the error handling, 3 out of 4 I tried were not scannable, the 1 I did manage to scan to me to a reviews site for the restaurant (where a lot of reviews said they struggled to make the QR work - likely not the feedback the restaurant wanted)! I guess it kept me entertained whilst waiting for the bill.

> Note that a lovely reader informed me shortly after publication that indeed I can include my full domain name in a version 1 QR code by using all capital letters instead of lowercase. TIL that the "alphanumeric" character set for QR codes actually contains symbols for URLs like : and /.

This is a nice trick worth remembering. I have used it myself in the past. Handy not just for creating ultra small QR codes, but also for getting as much data as possible into the limits of the largest QR codes.

I hand drew this on a whiteboard. It was a lot more work than I anticipated.

http://lars.nocrew.org/tmp/qr.png

I've really enjoyed reading the Grid World piece linked at the bottom of the post: https://alex.miller.garden/grid-world/

I once sent a letter to a friend with a hand-written QR Code whose content was the typed letter.

It's cool for the receiver, but tedious for the sender (but it's a good way to help with difficult to read cursive).

If someone needs a gift idea:

I used something like this on a large sheet and cut it into pieces for a puzzle gift to a website where people left comments. Nowadays even easier to generate nice temporary websites for such things.

I remember retracing QR codes on graph paper to pass time in grade 12 physics, this was back in 2013/2014.

Ah, I did just that this weekend.

Well... it wasn't QR-code but rather artoolkit markers. Let's just say I'll keep on printing them for a bit.

thats fun I would definitely scan this rather than a generated one

One time I tried to understand the QR algorithm and I didn't understand it at all despite trying multiple times.

Maybe I can try again with the help of LLMs. Hmm not a bad idea