QR code guides.
How the format actually works, and what to get right before you print a code at scale.
A QR code that works on your screen can still fail on paper. The gap between the two is not luck — it is a short list of physical constraints: how small a module a phone camera can resolve, how much contrast a scanner needs, how much of a code can be damaged before error correction gives up. None of it is difficult, but all of it is invisible until a print run fails.
These guides cover that ground once, properly. Each one makes concrete, testable claims — module sizes in millimetres, scanning distances, named failure modes — rather than the “make sure your QR code is high quality” advice that fills this topic. Read the one that matches your problem; they stand alone and none assumes you have read the others.
- Are QR Codes Safe? Risks and Real DefencesThe honest threat model. The code itself is inert ink; the risk lives entirely in where it sends you. What a quishing attack looks like in the wild, and the checks worth making before tapping through.
- QR Code Error Correction Levels ExplainedWhat the four correction levels actually buy, what each one costs in module density, and when raising the level is the right call — including why adding a logo means choosing the highest level rather than hoping.
- QR Code Size for Print: A Sizing GuideThe arithmetic that decides whether a printed code scans: module count multiplied by minimum module size, checked against how far away the reader stands. With the worked numbers for business cards, posters and packaging.
- What Is a QR Code? How the Format WorksThe foundation piece: how a grid of black and white squares encodes text, what the three large corner squares are actually for, and what happens in the second between pointing a camera at a code and a page opening.
- Why QR Codes Don't Scan, and How to Fix ItA diagnostic list ordered by how often each cause turns up in practice: low contrast, inverted colours, modules printed too small, a crowded quiet zone, glare off the material. Work down the list and a failing code usually confesses.
When the question is a choice between two named options — static or dynamic, PNG or SVG — it is answered in the comparisons instead, side by side. And everything the guides recommend is already the default in the generators: adjustable error correction, SVG export for print, and codes that never expire because nothing sits between the pattern and the payload.