QR Code

A QR Code (Quick Response Code) is a two-dimensional barcode. While a regular barcode holds a few digits in one line, a QR Code holds hundreds of characters in a square — almost always a web address.

Static and dynamic

• Static — the content is baked into the pattern itself. Once printed, it cannot change. If the link changes, the code dies.
• Dynamic — points to an intermediate redirector. You can change the destination after printing and, above all, measure how many people scanned it.

For printed material with a run size, dynamic almost always pays off: the cost of reprinting because a link changed is higher than the redirector's cost.

Error tolerance

A QR Code has built-in error correction: it stays readable with up to about 30% of the area damaged. That is why a logo can sit in the middle without breaking the code — as long as it does not cover the three large squares in the corners, which are the orientation markers.

WhatsApp's two QR Codes

Do not confuse the two:

1. Linking QR — the one that shows up when linking WhatsApp Web or a device. It is temporary, changes every few seconds, and should never be photographed or shared: whoever scans it connects to your account.
2. Contact QR — leads to a conversation with the number, and can come pre-loaded with a message. This is the one printed on storefronts, menus and packaging. You can generate one at ferramentas/qr-code-whatsapp.

⚠️ Security: scanning a QR Code from an unknown source — a sticker on a parking meter, a suspicious invoice, a street poster — is a common scam vector. The code hides the address, and you can only check it after the phone shows the link.