Reading linear and two-dimensional codes
EAN-13 and EAN-8 carry the GTIN of a retail product. UPC-A and UPC-E are the North American variants. Code 128 handles variable data and is standard on shipping labels, Code 39 lives in industry, ITF-14 marks cartons. The decoder detects each of them without you selecting a mode first.
Data Matrix, Aztec, PDF417 and GS1 QR add a second layer: the result is not just a number but a structured GS1 message. Application identifiers such as (01) GTIN, (10) batch, (17) best-before and (21) serial are extracted and labelled. That is the difference between a store-bought scanner and a tool for goods-in.
Check digit, GTIN and origin
Every EAN/UPC ends in a check digit. We recompute it with the GS1 modulo-10 rule. If it does not match, the code was printed or generated incorrectly. On a valid code we also show the GS1 prefix country — 400–440 Germany, 300 France, 690–699 China, 000–019 USA. The prefix is a registration range, not proof of where a product was made.
Why your images never leave the device
The decoder is JavaScript running in your browser. Camera frames are drawn into a canvas and read there; uploaded images are read through FileReader. There is no upload endpoint for image data. That is an architectural decision, not a slogan: the application has no route that accepts image content.
To improve the tool we store anonymous counters only — detected format, payload category (Wi-Fi, product code and so on), interface language, and whether decoding succeeded. No decoded content, no filenames, no IP-based profiling. Scan history lives in your browser’s localStorage and is deleted with one click.
When a code will not scan
The usual suspects are low contrast, a code that is too small, or reflections on a laminated label. Steady the camera, zoom slightly, and make sure the quiet zone around the code is visible. For a photo, rotating it often helps the decoder find the alignment pattern.
For damaged codes, try a second angle. For product barcodes we validate the EAN-13 check digit and tell you immediately when the number cannot be genuine. Industrial Data Matrix payloads (VDA 4902, GS1) are also supported — and our label generator handles the printing side.
FAQ
Frequently asked questions
What is the difference between a barcode and a QR code?
A barcode usually stores one number in one line; a QR code stores data in two dimensions. The scanner reads both families and parses the payload accordingly.
Can I scan an EAN-13 with my phone?
Yes. Camera scans work best with strong contrast and enough distance. For screenshots the decoder upscales small codes so they remain readable.
Does the scanner find product names?
Deliberately not. There is no reliable free product database. We return the GTIN, the check-digit verdict and the GS1 prefix country — enough to research the item yourself.
Are VDA and Odette logistics codes supported?
The Data Matrix payloads are decoded. To create and print VDA 4902, KLT or MAT labels we link to our label generator.
Is the barcode scanner really free?
Yes, with no sign-up and no scan limit, including check-digit calculation and batch image processing.