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A QR code is just a grid of dark and light squares, but plenty of small choices decide whether a scanner can read it: the error-correction level you pick, the contrast between the modules and their background, the quiet-zone margin around the edge, and the file format you export. These plain-English guides explain how each one works and how to keep a styled code scannable — the same rules the live scannability check on this site enforces.
Why won't my QR code scan?
The most common reasons a QR code fails to scan — low contrast, oversized logo, thin quiet zone, inverted colors, and density — and how to fix each.
QR error correction explained
What the L / M / Q / H error-correction levels mean, how Reed-Solomon recovery lets a damaged or logo-covered code still decode, and which level to choose.
Contrast for machine vision
Why a QR scanner needs luminance contrast, not just different hues — the ratio to target, why light-on-dark codes fail, and colors that still read.
SVG vs PNG QR codes
When to export a QR code as vector SVG versus raster PNG — print scaling, file size, transparency, and editing — with a clear recommendation for each use.