Static QR codes: what can change after printing?

The encoded content is fixed

A downloaded QR image contains a fixed payload. To change a phone number, Wi-Fi password or literal text, generate a new code. A URL code continues to contain the same address, although the owner of that website can change the page served at that address. A code for an unavailable page still encodes an unavailable address.

Match the payload to the task

URL QR encodes a web address. Wi-Fi QR uses a network configuration payload. Email and phone codes use their corresponding URI schemes, while vCard encodes contact fields. These payloads depend on the receiving scanner and application; scanning does not guarantee that every phone will perform the same action.

Reference: ZXing: commonly used QR payload formats

Download, inspect and test

Choose PNG for a raster image or SVG for a vector asset in a layout. Keep the supplied four-module light margin and strong contrast. Avoid stretching the QR or covering its modules with artwork. More content makes a denser code, so shorten unnecessary text and test at the final display or print size.

Reference: DENSO WAVE: QR area and quiet zone

Read unfamiliar codes before following them

QR Scanner from Image displays decoded content for review. Confirm the destination domain before visiting a link. Decoding a QR does not authenticate its creator or establish that the destination is safe.