Barcode & product-data guides

A GTIN is the GS1 Global Trade Item Number that sits above UPC, EAN and the 14-digit case code as one shared product identifier.

A practical guide to checking that a UPC, EAN, or GTIN is well formed before you trust it.

UPC is not an alternative to GTIN. A UPC-A barcode carries a 12-digit GTIN-12, so UPC is one member of the wider GTIN family.

An EAN-13 barcode is a 13-digit GTIN-13 built from a GS1 prefix, a company prefix, an item reference and a check digit.

GTIN-14 identifies a packaging level such as a case or carton by adding an indicator digit in front of the base product GTIN.

Compute the modulo-10 check digit for any UPC-A or EAN-13 with a pen, paper, and one small rule.

The seven reasons a UPC or EAN check digit fails validation, and how to fix each one.

How UPC-E compresses a 12-digit UPC-A into 8 digits, and why they share a check digit.

A developer-focused walkthrough of how a barcode API turns a scanned GTIN into structured product data inside your application.

A fair, category-by-category look at barcode and UPC database APIs so you can pick the right one for your use case.

A practical blueprint for wiring a camera scanner to a product-data API so users can scan an item and see what it is.

A field-by-field explanation of what you get back from a product-data barcode API and how to handle uneven results.

Learn how to read the barcode on a sneaker box and look it up on barcodes.gg to confirm which shoe you are actually holding.

Understand how Nike box barcodes and style numbers relate, and how to look up a Nike barcode on barcodes.gg to confirm the exact model and colorway.

An honest look at what a barcode lookup can and cannot tell you about sneaker authenticity, and how to use it as one signal among several.

Understand the difference between looking up a product by SKU or style number versus by barcode, and when each one is the right move for sourcing.