Data Matrix reader: decode any code online

With your phone

Open this page in your phone’s browser, tap Camera, then Start camera. Your browser asks for permission first. Hold the phone so the code fills about half of the square guide; the reader stops as soon as it has a result. A scanner app that supports Data Matrix works too. Some built-in camera apps only look for QR codes.

With a barcode scanner

Use a 2D imaging scanner (often sold as a “2D imager” or “area imager”). Codes etched or dot-peened into metal (direct part marking) can need an industrial reader with its own lighting. For production lines, use a fixed 2D reader rather than a phone.

What the result means

Text

The data exactly as stored. Invisible characters are shown as small gray tags: GS is the group separator that splits GS1 fields, CR LF are line breaks, and spaces at the start or end are marked. Copy copies the real characters, not the tags.

Symbol size

Rows × columns of modules, such as 24 × 24 or 16 × 48. Square sizes run from 10 × 10 to 144 × 144; rectangles from 8 × 18 to 16 × 48. Longer rectangles marked DMRE (ISO/IEC 21471) are newer and not every scanner reads them.

Symbology identifier

A short code a scanner sends before the data. ]d1 is a plain Data Matrix (ECC 200), ]d2 is GS1 DataMatrix, ]d3 is AIM application data, and ]d4 to ]d6 are the same three with a character-set marker (ECI).

Character set

How bytes become letters. Plain ASCII needs nothing. Accented letters with no marker are read as ISO-8859-1, the Data Matrix default. An ECI marker such as ECI 26 (UTF-8) tells the scanner exactly which set to use.

Bytes as hex

Every byte in the code, in hexadecimal. Use it to check data exactly, for example to spot a stray space (20) or a GS separator (1D).

Error correction used

How much of the code’s built-in error correction the read needed. 0% means a clean read; a high number means damage, blur or glare. It is a rough guide from the decoder, not a print-quality grade (that needs an ISO/IEC 15415 verifier).

Reading GS1 DataMatrix

A GS1 DataMatrix starts with a special FNC1 character, so the scanner reports ]d2. The data is a chain of GS1 Application Identifiers (AIs): a number in brackets that says what follows, such as (01) for the product’s GTIN or (17) for the expiry date. The brackets are printed under the code for people; they are not in the code itself. A field whose length varies, such as a batch number, ends with a separator that scanners send as the GS character, shown here as GS.

The sample code on this page holds this data, as a scanner sends it:

01095060001343521728123110ABC123GS21SN000417

The reader splits it into fields like this:

For each field the reader shows its name, the value, a readable date or measure, and whether the check digit is correct. It checks the syntax of every field against the GS1 Barcode Syntax Dictionary. It can’t tell you whether a GTIN is registered or who owns it. Learn what the GS1 fields mean, or make your own with the GS1 DataMatrix generator.

If a code shows GS1-looking text with the brackets inside it, such as “(01)0950…”, it was made as a plain Data Matrix. GS1 scanners will not split it into fields. The reader warns you and offers to make a real GS1 DataMatrix with the same data.

Private by design

Many online readers upload your image to a server. This one doesn’t. The decoder is zxing-wasm, a WebAssembly build of the open-source ZXing-C++ library, and it is served from this site. Your browser opens the image, the decoder reads it on your device, and the result stays on the page. Camera video is decoded frame by frame in the same way and is never recorded or sent. After the decoder has loaded once (about 1 MB), reading works without a connection.

We count only anonymous events, such as “a code was read from an upload”, never the decoded data or the image. See the privacy policy.

Tips if a code won’t read

• Get closer. Crop the photo or zoom in so the code fills a good part of the picture. Each small square needs a few pixels.
• Keep it sharp. Hold still, let the camera focus, and avoid motion blur. A screenshot of a PDF works better than a photo of a screen.
• Light it evenly. Avoid glare on glossy labels and shadows across the code. On metal, tilt the part slightly to lose reflections.
• Keep the blank border. The quiet zone (the empty margin around the code) must be in the picture and clear of text or edges.
• Check the options. Light-on-dark codes and rotated images are on by default. Turn on “Also read other codes” if it may be a QR code.
• Etched or dot-peened parts (direct part marking) can be beyond a phone camera. An industrial 2D reader with the right lighting reads them.

Still stuck? Fix a Data Matrix that won’t scan. If you made the code yourself, create a Data Matrix code again at a larger size with at least a 2-module blank border.