QR codes are one of those things I use almost daily - mostly for UPI payments - but I realized I had no idea what’s actually going on behind them.
Like… it just looks like a bunch of random squares, right?
So I went down a small rabbit hole trying to understand:
- how data is stored inside them
- why they still scan even when partially damaged
- and what those big squares in the corners actually do
What I found (in simple terms)
A QR code isn’t random at all.
It’s basically:
- encoded data (text / numbers / payment info)
- some smart error correction (so it still works if parts are missing)
- and fixed patterns that help scanners orient the code
That’s why you can scan a slightly broken QR code and it still works fine.
I tried making a video about it
I wanted to explain this visually, so I recorded a short video.
Fair warning - it’s my first time doing this kind of thing, so it’s a bit rough around the edges
But I tried to keep it simple and intuitive.
Would genuinely love feedback
- Was anything confusing?
- Did I oversimplify something important?
- What topic should I try next?
Side note
While trying to understand this, I came across a really well-written series by @maxart2501 on building a QR code generator.
It helped me connect a few dots around how QR data is actually structured and encoded.
If you're curious about going deeper into the implementation side, I’d definitely recommend checking it out:
https://dev.to/maxart2501/series/13444
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