A payment QR code is just twelve lines of text
If you have paid an invoice in Europe recently, you have probably pointed your banking app at a small square and watched it fill in the payee, the IBAN and the amount by itself. I run ibanchecker.cash and I spent the last few weeks on both sides of those squares: generating them and reading them back. The format turned out to be far simpler than most people expect, and a couple of its rules…
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