QR code documentation
The reference we wanted to exist: what QR codes are, how the format actually works, what scans and what doesn't, and the exact numbers for printing them. 54 pages, no paywall, no email gate, and no reason to exaggerate — we have nothing to sell you.
Every page is also served as plain markdown at {path}.md for machines, and indexed in /llms.txt.
QR code basics
10What a QR code is, how it works, why you would use one — and the cases where you shouldn't.
QR code specification and internals
2The ISO/IEC 18004 machinery: versions, capacity, error correction, masks, encoding modes. Every number here is implemented and tested in our open-source core.
How to make, scan and use QR codes
4Task guides. Each one ends with a working generator, prefilled.
QR code design and customisation
2Colours, shapes, logos and frames — and the contrast and coverage limits past which a code stops scanning.
Printing QR codes
4Sizes, DPI, substrates, inks and durability. The cluster where a wrong answer costs a print run.
Scanning and device compatibility
1What scans what, from iPhone cameras to warehouse imagers.
QR code troubleshooting
8Something isn't scanning. Find the cause, in order of likelihood.
QR code security and privacy
4Quishing, malicious stickers, what a QR code can and cannot do to your phone, and what your generator can see.
QR code payments
7UPI, PIX, EPC/SEPA, EMVCo and crypto payment codes — field by field, from the actual specs.
QR codes for ecommerce and retail
2Packaging, labels, reviews, returns and loyalty — the offline-to-online loop.
QR codes for social media and marketing
1Creator, campaign and out-of-home use, and what scan rates to actually expect.
QR codes for developers and AI agents
6Generate QR codes from any language, decode them, verify them, and wire them into agents.
QR code reference tables
3Capacity, module counts, error-correction blocks and size-by-distance — generated from the spec, not copied from a blog.