QR code test
Find out what a code really contains, whether it depends on someone else’s server, and how it copes with a small print, a shaky hand and bad light.
What the test tells you
A QR code is text in a pattern. The first thing the test does is read that text and say what it is: a web link, a Wi-Fi network, a contact card, an event, a payment. For a web link it also checks the domain. If the link points at a redirect service rather than a real destination, the code is dynamic, and it will stop working the day that service stops forwarding it. That is the single most common reason a printed code dies.
The second thing it does is stress the image. It shrinks it to the size of a small print, blurs it, fades its contrast, and squashes it as if scanned from the side, then asks a real decoder to read each version. A code that fails the small-print test will fail on business cards. A code that fails the blur test will fail on a moving phone. The original design file scores higher than a photo of a print, which is as it should be: the print has already been through the real world.
If the code does not read at all
Nine things cause that, from no quiet zone to an oversized logo to inverted colours. The guide on codes that will not scan goes through them in the order to check. If the code reads but the page it points to is gone, see what to do when a code expired.
Questions
Is my image uploaded anywhere?
No. The decoder runs in your browser. The image never leaves your device, which also means you can test codes that contain private data such as Wi-Fi passwords.
Why does my code decode here but not on my phone?
A decoder working on a clean file is more forgiving than a camera in bad light. The five robustness tests simulate that gap. If the small-print or blur test fails, the code is the problem; if everything passes, check the destination link and the quiet zone around the print.
What does "dynamic code on a redirect service" mean?
The dots contain a short link on another company’s domain rather than your destination. Those codes work only while that company forwards the link, which usually means while a subscription is paid. Our guide on expired codes explains the options.
Can I test a code printed on paper?
Yes. Take a photo straight on in good light and upload it. Expect a lower robustness score than the original file: the photo already carries real-world blur and perspective.