What a QR code is

The square of black and white dots is a QR code, for “quick response”. It holds a short text, most often a link, that a phone's camera reads in an instant and opens: a website, a menu, a WhatsApp chat or a Wi-Fi network. A Japanese company invented it in 1994 to track car parts; it is everywhere now because every phone reads one without an app.

It is not the striped barcode on a product at the checkout, which is a product number read by a till scanner. This article is about the square one.

How it works

  • The three large squares in the corners show the camera where the code is and which way up, so it can be read at an angle or upside down.
  • The small dots between them are the content itself, written in dots. The longer the content, the more dots there are and the smaller they get.
  • The code carries a spare copy of its content, so it still scans when dirty or when a logo covers part of it. That is why your logo can sit in the middle without breaking it.

How to scan a QR code

  1. Open the phone's camera and point it at the code, without taking a picture.
  2. A link or a notice appears over the picture: tap it to open what the code holds.
  3. If nothing appears, some phones read codes from Google Lens or from a scan button in the quick settings.

When the code is a picture on your phone or in a message, no camera can scan it: open the QR code scanner and choose the picture. It reads it in your browser without uploading it, and shows what the code holds; if it is a link, you see it before you open it. That is also how you turn a QR code back into a link to copy.

How to create a QR code

  1. Open the QR code generator and choose what it opens: a link, WhatsApp, Wi-Fi or another kind.
  2. Type the content, or paste the link.
  3. If you like, change the colours and shapes and put your logo in the middle.
  4. Download it: PNG or SVG for screens and the web, PDF for print.

Every kind has a page that walks through it, such as link to QR code and image QR code.

Static or editable

A static code holds its content in its pattern: it never stops working and depends on no one, but changing the content means a new print. An editable code holds a short link, so you change what it opens after printing and see how often it was scanned. The difference in detail

Are QR codes safe?

The code itself is harmless: it is a link written in dots. The risk is the link it opens, as with any link you tap. Read the link the camera shows before opening it, and beware of a sticker pasted over a genuine code in a public place. On Kuody, a link that imitates a known name is held behind a warning page, and anyone can report a code.

Before you print one

Scan it with two different phones, and print it at a size that suits the distance it is scanned from: the size calculator gives the smallest width that scans. Keep it dark on a light background, with a clear margin around it. Downloading and printing