GS1 Barcode & Digital Link Decoder

Input. An image or a PDF page with a barcode, or text in one of three forms: the human-readable form (01)09506000134352(10)ABC123(17)261231, a raw element string where variable-length elements are separated by the group separator (shown as GS, <GS> or {GS}), or a Digital Link web address. For images the tool tries QR codes with a light-weight reader first and uses the zxing-cpp engine (served from this site as WebAssembly) for DataMatrix, GS1-128, Code 128 and DataBar. The symbology identifier the scanner reports (for example ]d2 for GS1 DataMatrix, ]C1 for GS1-128, ]Q3 for GS1 QR code) is shown.

What is explained. Each element gets its AI, its meaning (GTIN, SSCC, batch or lot, expiry, best-before, serial number, count, net weight with the decimal position, GLN, price, country code, internal information and many more), its value in a readable form (dates as 2026-12-31, measures with the decimal point placed), and notes. The table covers a fixed list of Application Identifiers from the GS1 General Specifications; an identifier that is not in the list is reported as unknown instead of being guessed.

Checks. Check digits (modulo 10) are verified for GTIN-8/12/13/14, SSCC, GLN, GSIN, GSRN, ITIP and the key part of GDTI, GCN and GRAI; fixed lengths and numeric fields are verified; dates must be real (day 00 means the last day of the month); the order of key qualifiers in a Digital Link (for a GTIN: consumer product variant, batch, serial) is compared with the standard. A GS1 Digital Link written in the uncompressed form (release 1.7.0, ratified August 2026) is parsed; compressed Digital Link URIs are recognised and not decoded.

Why the separator matters. In an element string, variable-length elements must be followed by the group separator unless they are last. If a scanner removed the separators, the first variable element swallows everything after it. The decoder warns when it sees this pattern.

Images (PNG, JPEG, WebP up to 30 MB) and PDF (up to 50 MB, first 40 pages) containing QR, DataMatrix, Code 128 / GS1-128 or DataBar barcodes; pasted element strings, bracketed HRI text and uncompressed GS1 Digital Link addresses. Not decoded: compressed Digital Link URIs, EAN/UPC retail codes without AIs (they carry only a GTIN) and barcodes damaged beyond what the reader engine can read.

1. Drop a picture or PDF of the label, or paste the text from a scanner or the Digital Link address.
2. Read the table: each Application Identifier, its meaning, the value in readable form and any problem.
3. Copy a single value, or the whole code in the bracketed form.
4. If a barcode is not found, try a sharper or larger picture, or paste the scanner's text.

• Checking what batch and expiry a pharmaceutical or food label carries
• Verifying the GTIN check digit of a product code
• Understanding the contents of a logistics label (SSCC, GTIN, quantity)
• Testing that a printer or software writes a correct GS1 DataMatrix or Digital Link
• Learning what each Application Identifier on a barcode means

The Application Identifier table is a fixed list taken from the GS1 General Specifications; an identifier added in a newer release is shown as unknown. Not every barcode variant, printing defect or scanner configuration is supported, and the reader engine can miss a code or read a damaged one wrongly, so a code that does not decode is not necessarily invalid.

A correct check digit shows that the number is internally consistent, not that a product or code is genuine, registered or safe. Date century handling is simplified (years are read as 2000-2099). The tool does not look anything up online.