QR Code Generator

What a QR code actually encodes

A QR code is a two-dimensional barcode that stores data in a grid of black and white modules. A camera reads the pattern and decodes the bytes back into text. Most often that text is a URL, but it can just as easily be plain text, a Wi-Fi network configuration, contact details in vCard format, or a payment string. The code itself is just data; what the scanning app does with it depends on the content.

Generators are handy for linking a printed poster to a landing page, putting a menu behind a sticker on a table, sharing a Wi-Fi password without reading it aloud, or adding a scan-to-contact square to a business card.

Error correction and why size changes

QR codes have four error-correction levels, and this is the setting most people overlook. Level L recovers about 7 percent of lost data, M about 15 percent, Q about 25 percent, and H about 30 percent. Higher correction means the code still scans even if part of it is scratched, smudged, or covered by a logo, but it also packs in more modules, so the pattern gets denser for the same message.

Content: https://example.com/menu
Level L  -> smaller, denser-looking, fragile if damaged
Level H  -> larger grid, survives a logo in the center

Wi-Fi payload format:
WIFI:T:WPA;S:MyNetwork;P:mypassword;;

That Wi-Fi string is a real example: a phone that scans it offers to join the network directly, which is why the fields follow an exact format with the type, SSID, and password.

Questions worth knowing

Why does my code fail to scan? Usually contrast or size. Keep dark modules on a light background, not the reverse, and preserve the quiet zone, the empty margin around the code. Printing it too small or at low contrast is the most common cause of a code that will not read.

Can I put a logo in the middle? Yes, if you use a higher error-correction level like Q or H. The correction data lets the scanner reconstruct the modules the logo covers, as long as the logo stays modest in size.

Can I change where it points after printing? Not for a static code, because the destination is baked into the pattern. If you need to redirect later, encode a short link you control and change where that link forwards.