What is a Barcode?

A Barcode (often referred to as a UPC, EAN, or GTIN) is a standardized, machine-readable string of numbers represented visually by parallel black bars.

Unlike internal SKUs, barcodes are globally unique and regulated by official standardization bodies (such as GS1). The exact same barcode numbers identify a specific manufacturer product worldwide across Amazon, Walmart, Target, and independent Shopify stores.

Barcode Formats

  1. GTIN-12 (UPC-A): 12-digit format primarily used in North America.
  2. GTIN-13 (EAN-13): 13-digit format used globally outside North America.
  3. GTIN-14 (ITF-14): 14-digit format used for shipping cartons and wholesale master cases.
  4. ISBN: International Standard Book Number used exclusively for books.

Why Are Barcodes Important in Ecommerce?

  • Marketplace Requirements: Platforms like Amazon, Google Shopping, eBay, and Meta require valid GTIN barcodes to list products.
  • Automated Warehouse Scanning: Handheld laser scanners read barcodes instantly during picking and packing.
  • Counterfeit Prevention: Verified GTIN registration proves product authenticity.

Common Confusion

Developer Takeaway

GTIN Validation Rule: When accepting barcode inputs in forms or API endpoints, enforce strict length checks (12, 13, or 14 digits) and validate the final check digit using the GS1 Modulo-10 checksum algorithm to catch typo errors.