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Unfortunately it seems that every online explanation of QR codes always leaves out the Reed-Solomon error code calculation. The author here describes it as “long, tedious, and not very interesting”, but since everyone seems to think that, it is now very hard to find.

The feedback he receives is quite fun: https://www.nayuki.io/page/poor-feedback-from-readers

Plug: Now that you know how they work, you can use them in your SQL queries too https://github.com/Florents-Tselai/pgQR

Recent Veritasium video on the topic, "I used to hate QR codes. But they're actually genius":

* https://www.youtube.com/watch?v=w5ebcowAJD8

A good practice is to tag the title with the year of the article (in this case, 2018), when it is not from the current year.

This is pretty awesome. I would like to see the same thing for the decoder.

it's nice to have an explanation. for me, I just wanted to quickly make them. Googling led to ad covered sites and "register to use" site. Found a few on GitHub but they had other issues so threw together my own using a well designed library I'd used before. took about 15 minutes

https://greggman.github.io/qr-code/

might add more options but in truth I don't think most users need the options

This resource is awesome. I wanted to have the smallest readable QR code for my printables pages footer [1], and I discovered there that it's possible to encode URLs in "Alphanumeric mode", version 1, using only uppercase characters, e.g., HTTPS://FOO.CC/ABCDEFGHIJ, so I got a three letter domain name and built the simplest URL shortener hosted on a CF worker.

[1]: https://pdf.ahaprintables.com/pdf/preview/aha/zebra-puzzles-... (PDF)

Nice! Learning how QR codes work has been on my todo list for ages, this was a nice introduction.

I built an implementation in Rust a while back:

https://github.com/aabiji/qr