Guides for custom QR codes

Practical references for the decisions that do not fit inside a control: print reliability, QR capacity, custom styles, logos and privacy. Recommendations are explained, not presented as magic numbers.

Make a custom QR code that still scansYour QR code can look like part of your brand, not an afterthought. Start with its destination, choose a visual style, then test the finished file where people will actually scan it.
QR code error correction levels: L, M, Q and HWhat each level really restores, the capacity it costs, and the cases where H is the wrong answer.
How big should a QR code be?Two numbers decide it: how wide one module ends up, and how far away someone stands.
Static and dynamic QR codes, comparedOne encodes your destination, the other encodes someone else's short link. That difference decides everything else.
Can a QR code be hacked?The symbol cannot do anything. Everything dangerous about a QR code is what the text says and what your phone does next.
Printing QR codes: CMYK, contrast and paperA decoder sees greyscale. Most print failures are a colour decision, a registration problem or a missing quiet zone.
Why Wi-Fi QR codes fail to connectAlmost every failure is one of four things: escaping, an all-hex SSID, a hidden network flag, or a client that never supported the format.