Barcode scanner

Reembun. (2026, July 31). Barcode scanner. https://reembun.com/barcode-scanner

Linear and 2D, and why they fail differently

Symbology	Holds	Typical use
EAN-13	13 digits	Retail products worldwide
EAN-8	8 digits	Small retail packaging
UPC-A	12 digits	Retail in the US and Canada
ISBN	13 digits, 978 or 979 prefix	Books
Code 128	Any ASCII, variable length	Shipping, logistics, internal labels
Code 39	Letters, digits, a few symbols	Industry, defence, older systems
ITF-14	14 digits	Cartons and outer packaging
GS1 DataBar	GTIN plus weight or expiry	Fresh food, coupons
Data Matrix	Any data, very small footprint	Component marking, pharmaceuticals
PDF417	Around 1,800 characters	Licences, boarding passes, ID

The practical split is not linear against 2D, it is whether the symbology carries error correction. Data Matrix, PDF417, Aztec and QR all do, and all survive real damage. EAN, UPC and Code 128 carry at most a single check digit, which detects an error without being able to repair one.

What the check digit actually proves

Every retail barcode ends with a digit calculated from the ones before it. Take the digits from the right, multiply alternately by three and one, add them up, and the check digit is whatever takes that total to the next multiple of ten.

That catches every single digit error, and most transpositions of adjacent digits. It catches nothing about whether the product exists, who made it, or whether the number was printed by someone entitled to use it.

So a valid check digit means the number was read correctly. It does not mean the number is real. This tool reports exactly that and no more, which is the difference between a scanner and a lookup service.

The country prefix, stated correctly

The first three digits of a GTIN identify the GS1 member organisation that allocated the company prefix. That is nearly always the country in which the brand owner registered with GS1.

It is not the country of manufacture. It is not the country of origin for customs purposes. It is not where the product was packed. A brand registered in Australia manufacturing in China ships an Australian prefix, and a Chinese manufacturer registered locally ships a Chinese one on a product sold under a European brand.

The frequently shared advice to avoid or prefer certain prefixes to buy from a particular country is therefore wrong at the root, and it has been wrong since GS1 said so publicly. The tool names the issuing organisation, and puts that qualification next to it every time.

Scanning a 1D code reliably

Linear codes are much fussier than QR codes about how you photograph them:

Get the whole width. A barcode with either end cropped is unreadable. There is no partial answer, because the quiet zones at each end are part of the symbol.

Hold it level. Rotation is handled, but a code photographed at a steep angle stretches the bar widths unevenly across the frame, and bar width is the entire encoding.

Watch for curve. A code wrapped around a bottle or a tin bends the bars, and past roughly 30 degrees of curvature there is no reading it flat on.

Fill the frame horizontally. Bars are thin, and each one needs at least two or three pixels. Distance kills a 1D code much faster than it kills a QR code.

Camera or photo

Both work identically. The camera scans continuously and stops on the first hit, and the image path reads a photo, a screenshot or a picture someone sent you. Everything is decoded in this tab, and nothing about the code, the photo or the camera stream is transmitted.