QR code generator

How to use it

1. Paste the URL or text you want encoded.
2. Set the size and error-correction level, then download the PNG or SVG.
3. Print it large enough: as a rule, the code should be at least a tenth as wide as the distance it is scanned from.

The dynamic-QR business model, and the phishing problem it created

Most free generators produce a dynamic code: it encodes a short link on their domain, which redirects to yours. That buys editability and scan analytics. The code dies when the service folds or moves that feature behind a paywall — menus and estate agents' boards printed a few years ago are already dead this way — and every scan is logged by a third party holding the scanner’s IP and timestamp.

It also removes a defence. A phone shows the destination before opening it, so a person can read the domain — unless that domain belongs to a shortener, in which case the readable part conveys nothing. Quishing leans on exactly this: a sticker over the genuine code on a parking meter, or an image in an email carrying no link for a text filter to inspect.

Error correction, capacity and the quiet zone

The four levels come from ISO/IEC 18004: L recovers roughly 7% of a damaged code, M 15%, Q 25%, H 30%. That allows a logo in the centre — at H a badge covering a fifth of the area still reads. But correction data occupies the same grid as the content, so raising the level pushes the code to a larger version with finer modules, which need more print resolution.

Two things break more codes than anything else. The quiet zone — four modules of blank margin on every side — is part of the specification, not decorative padding, and cropping it flush against a coloured panel is the commonest reason a code that looked fine in a layout will not scan off the page. The other is polarity: decoders expect dark modules on light, and many cope with inversion but not dependably.

Questions