Read a QR code

The case a phone cannot solve: the QR on the same screen

A QR code turns up in a chat, inside a PDF, in an email or on a page you are already looking at. A phone cannot point at itself, so people end up printing the code or borrowing a second phone. Here you just take a screenshot and paste it with Ctrl+V (⌘+V on a Mac): the code is read from the image in your clipboard. The same goes for a QR sitting inside a photo: you can drag the file in as it is.

What is really inside a QR code

It is not a mysterious picture: it is text. What changes is the shape whoever made it gave that text, and here it is recognised and shown piece by piece. A Wi-Fi network becomes name, password and security type, with the password copied in one tap: handy when you have to type it on a computer or a TV. A contact becomes name, phone and email. And then links, email addresses, phone numbers, ready-made text messages, places on the map.

Why the link is not opened for you

Because a QR code is, quite literally, a piece of paper: anyone can print one and stick it over the real one, on the parking meter, on the menu or on a bill. It is a common scam and the eye cannot catch it, because those little squares are unreadable to us. Here the link is shown in full, with the domain it leads to written separately, and opening it is your own, separate move. The same care goes to authenticator codes: if one turns up, you are told it is a secret key and must not be shared.

When a code cannot be read

It happens, and it is worth saying how things stand. The reader was put through 23 images deliberately mangled: rotated by 5, 15 and 45 degrees, blurred, covered in speckles, with no contrast, with the colours inverted, tiny, photographed at an angle with a shadow across them, sitting inside a screenshot, with no white border. It reads 22 out of 23. The one it misses is genuinely blurred, and no program reads that. If your code does not go through: crop the image around it, take the photo again closer and steadier, and leave some white around it.

Where the image ends up, and where the rest is

Nowhere: the photo is read inside the page, by your own browser, and no network request goes out. The camera, if you use it, asks the browser for permission and switches off when you press the button or leave the page: the video is neither recorded nor sent. If instead you need to create a QR code, those are already here: QR code generator for links and text, WiFi QR code to get guests onto your network, and Barcode generator for product codes.