QR Code

Good to know

• Codes go from version 1 up to version 20, which is a little over 850 bytes at the lowest error correction level. Anything longer is refused rather than encoded: a symbol that overflows its version still looks like a working code and scans as nothing.
• More error correction means a bigger code, not a safer one for its size: the extra modules are the recovery data. Q is the usual choice for anything printed, where a smudge or a fold has to be survivable.
• The white margin around the code is part of it. Four modules of quiet zone is what the standard asks for, and a code cropped tight to its edge is one many scanners will not find at all.
• Text is encoded as UTF-8, which is what every scanner made this century assumes. Everything happens in your browser — nothing you type is sent to the server.