Blue QR Code
Yes, a QR code can be blue. Dot color and background color are both fully customizable to any hex value in QRSen's generator, not limited to a handful of presets — the real constraint isn't color choice, it's contrast.
QR scanners work by detecting the difference in light reflectance between dark modules and their background, not by detecting "black" specifically. That means any sufficiently dark, saturated color reads the same way plain black does, as long as it stays clearly distinct from whatever background color sits behind it. Color choice is genuinely open; the constraint that actually matters is the contrast between the two colors you pick.
In concrete terms: a dark, saturated blue like navy on a white or very light background scans just as reliably as plain black on white. A lighter or more muted, pastel blue against a similarly light background is the risky combination, because the luminance difference between the two colors — how much lighter or darker one looks than the other — gets too small for a scanner to reliably tell modules apart from background, especially under weak lighting or on a lower-quality camera.
A useful practical test before publishing or printing: convert the design to grayscale and check whether the blue still reads as clearly distinct from the background once color is stripped away. Most phone camera apps and basic photo editors offer a quick desaturate or grayscale preview, and if the dots and background still look clearly different in grayscale, the color combination is almost certainly safe in full color too.
Since QRSen supports full hex control over both dot and background color, along with a transparent background option, setting up a blue QR code and previewing it live before exporting is straightforward — there's no need to guess how a chosen shade will hold up once it's generated.
Blue specifically is a popular brand-matching choice because so many companies already use a blue-dominant palette, and a navy or royal blue QR code reads as clearly intentional next to a matching logo or letterhead rather than looking like an unstyled default. It also tends to photograph and print more predictably than some other hues, since darker blues hold their contrast reasonably well across the shift from a monitor's RGB display to a printer's CMYK ink, whereas some other colors (certain greens and oranges in particular) can shift more noticeably between screen and print.
If a brand's exact blue is a lighter or more pastel shade, the safer approach is usually to use that lighter blue for a supporting design element — a border, a background panel behind the whole code — while keeping the QR dots themselves in a darker, more saturated version of the same hue. That keeps the overall design on-brand while preserving the contrast the scanner actually depends on.