Why Does Every QR Code Look Different?
A QR code's pattern is a direct visual encoding of its underlying data, so different content genuinely produces a different-looking pattern, it's not decorative or randomized. Two codes with completely identical content, version, error correction level, and mask pattern will come out pixel-for-pixel identical, but change any of that and the pattern changes too.
Every dark and light module in a QR code's grid corresponds to a specific bit of encoded information, structural markers, or error correction data, arranged according to the QR specification. Nothing in the pattern is filler or stylistic, even though it looks visually random to the eye, it's a deterministic, exact representation of whatever text or link went in.
Two QR codes that link to the same domain but a different page path, say yoursite.com/menu versus yoursite.com/menu2, will look meaningfully different once you look closely, because the underlying bytes being encoded are different, even by one character, and that changes how the data gets packed, error-corrected, and masked across the whole grid, not just in one isolated corner. There's no way to predict from a glance how similar two pieces of content are just by eyeballing the resulting pattern.
If the input content, the QR version, which determines grid size, the error correction level, and the mask pattern are all exactly the same, the resulting code will be pixel-for-pixel identical no matter which generator produced it, since the generation process is a deterministic algorithm, not a creative one. Different generators can still produce visually different codes for identical content if they choose a different error correction level or mask pattern by default, which is a common source of confusion when people compare codes from different tools.
None of this affects custom styling options like dot shape, color, or a center logo, those are cosmetic changes layered visually onto the underlying data grid and don't alter what's encoded, provided the generator keeps error correction high enough to compensate for any visual overlay. The actual black-and-white data pattern underneath is what a scanner reads, styling sits on top of that, it doesn't replace it.
This is also why comparing two QR codes side by side to judge which one is "better" or "more secure" based on appearance alone doesn't work — a denser-looking pattern isn't inherently safer or more legitimate, it just reflects more encoded content or a higher error correction setting. The only reliable way to know what a code actually does is to decode it, either by scanning it yourself or checking the raw text through a QR reader that displays the decoded content before opening any link.