QR code generator
Create a QR code from a link, some text or Wi-Fi credentials and download it as PNG or SVG. Everything runs in your browser, no data is ever sent online.
What the error-correction level is for
A QR code can still be read even when partly damaged or covered, thanks to error correction. The higher it is (up to "Highest"), the more the code stays readable when scratched or with a logo in the middle, but it needs more modules and the pattern gets denser. For everyday use, Medium is the best trade-off.
PNG or SVG?
Download the PNG to use it right away on social media, documents or slides. Pick the SVG if you need to print it large (flyers, signs, stickers): it's a vector, so it stays sharp at any size. Always keep good contrast between color and background, otherwise some readers won't be able to scan it.
More text, more squares
A QR code has no fixed size: it grows with what it holds, and it grows in steps (the «versions», from 21x21 modules upwards). A short address fits in a sparse grid readable from a distance; the same address with thirty characters of tracking produces a dense grid that has to be framed close up.
The practical rule is to shorten the text before generating the code, not to enlarge the code afterwards. On a poster, the difference between a 25-character URL and a 120-character one is the difference between a code readable from the pavement and one readable at half a metre.
A higher correction level is not always better
Error correction lets the code be read even when it is damaged or partly covered: at the highest level up to 30% of the code can be recovered. That is what allows a logo in the middle without breaking anything.
But redundancy takes space and thickens the grid: raising the level for the same text produces a denser code, and therefore one that is harder to read from a distance. A high level makes sense on a sticker that will get dirty or a badly printed label, not on a screen.
Where the code is printed changes everything
The two measurements that decide whether a QR works are physical size and reading distance: the rule of thumb is that the side of the code must be at least one tenth of the distance it will be framed from. A sign read at two metres needs twenty centimetres.
You also need the white margin around it, at least four modules wide, and real contrast: a dark code on a light background. Inverted (light on dark) many phones will not read it, and printed over a photograph almost nobody will.
Nearby tools
To check that the code you made is readable there is Read a QR code. The two most requested cases already have their own pages: WiFi QR code and WhatsApp link.