Scanning with a phone camera
Most smartphones scan QR codes directly in the camera app. iPhones have done this since iOS 11 in 2017, and most current Android phones do it in the camera app or through Google Lens. Pointing the camera at the code usually shows a banner or button with the decoded link.
Many other apps include their own scanner, such as messaging, banking and payment apps. These often only act on codes meant for that app, for example a payment request or a login code.
How a scanner decodes a code
A scanner first looks for the three finder patterns to locate the code, its orientation and its corners. It then corrects for angle and perspective, samples each module as dark or light, and reads the format information to learn the error correction level and mask. After removing the mask and correcting errors, it turns the data back into text, a link or another payload.
This is why good contrast, a clear quiet zone and modules large enough for the camera distance matter. Anything that hides the finder patterns or blurs the grid makes each of these steps harder.
Check the preview before opening
Most built-in scanners show the link or domain before opening it, and that preview is the best moment to check where a code leads. If the domain looks unfamiliar, misspelled or unrelated to the place the code is posted, it is safer not to open it. Some scanner apps open links automatically, which removes that chance to check.
- Read the domain, not only the first few characters
- Be cautious with shortened links from unknown sources
- Do not enter passwords or payment details on a page reached from an unexpected code