GS1 standards go far beyond simple barcodes. Global Location Numbers (GLNs), GS1 Digital Links, and Application Identifier 21 (serial numbers) form the backbone of modern supply chain traceability. Validating these identifiers correctly is essential for regulatory compliance, trading partner requirements, and QR-code-based product authentication. This guide breaks down each GS1 identifier type, explains its structure, and shows you how to validate them using our free tool.
Free GS1 Validation Tool
Validate GLNs, serial numbers (AI 21), and GS1 Digital Links. Generate Digital Link URIs from your GTIN data.
Validate GS1 Data - FreeUnderstanding GLN (Global Location Number)
A GLN (Global Location Number) is a 13-digit GS1 identifier that uniquely identifies a physical location, legal entity, or function within an organization. Think of it as a GTIN, but for places instead of products.
GLN Structure (13 digits)
GLNs are used for:
- Warehouse identification in logistics and shipping documents
- Trading partner identification in EDI (Electronic Data Interchange) messages
- Hospital and healthcare facility identification for medical device traceability
- Store and distribution center mapping for supply chain visibility
GS1 Digital Link Explained
GS1 Digital Link is a standard that encodes GS1 identifiers into a web URL. Instead of a barcode that only scanners can read, a GS1 Digital Link creates a URL that any smartphone can access. It connects physical products to their digital identity.
GS1 Digital Link Anatomy
https://example.com/01/09521234543213/21/ABC12345
GS1 Digital Links are increasingly used in QR codes on product packaging. When a consumer scans the QR code, they are directed to a web page with product information, authenticity verification, warranty registration, and more. Our validation tool can verify that your Digital Link URI is correctly structured according to GS1 specifications.
Serial Numbers (AI 21) Explained
Application Identifier 21 (AI 21) is the GS1 standard for encoding serial numbers. When combined with a GTIN, a serial number creates a unique identity for an individual product unit, not just a product type. This enables:
- Item-level traceability: Track individual units through the supply chain
- Product authentication: Verify that a specific unit is genuine, not just the product type
- Recall management: Identify exactly which units are affected in a recall
- Regulatory compliance: Required for pharmaceuticals (DSCSA) and medical devices (UDI)
AI 21 Format Rules
Serial numbers can be up to 20 characters long and may contain alphanumeric characters. They must be unique within the scope of their associated GTIN. Our validator checks both format compliance and character validity.
Why GS1 Validation Matters
Incorrect GS1 identifiers cause real business problems:
- Supply chain disruptions: Invalid GLNs break EDI messages and shipping documents
- QR code failures: Malformed Digital Links result in broken QR codes that show errors when scanned
- Regulatory non-compliance: Invalid serial numbers fail regulatory audits in pharma and healthcare
- Trading partner rejections: Partners using GS1-compliant systems will reject invalid identifiers
How to Use the GS1 Validation Tool
Our free tool supports three types of validation:
GLN Validation
Enter a 13-digit GLN to verify its check digit and structural validity.
Serial Number (AI 21) Validation
Enter a serial number to check format compliance, length, and character validity.
GS1 Digital Link Generation
Enter a GTIN and optional serial number to generate a properly formatted GS1 Digital Link URI.
For GTIN-level validation, use our dedicated GTIN Validator. To learn more about GS1 compliance in general, read our GS1 Compliance Guide.
Frequently Asked Questions
What is the difference between a GTIN and a GLN?
A GTIN identifies a product. A GLN identifies a location or entity. Both are 13-digit GS1 identifiers with a Mod-10 check digit, but they serve different purposes. GTINs go on product barcodes; GLNs go in business documents and supply chain systems.
Do I need GS1 Digital Links for my products?
If you use QR codes on product packaging, GS1 Digital Links are strongly recommended. They ensure your QR codes follow the global standard, making them compatible with retail scanners and consumer apps worldwide. GS1 has announced that 2D barcodes (including QR codes with Digital Links) will be accepted at point-of-sale globally by 2027.
Is the GS1 validation tool free?
Yes. Validate GLNs, serial numbers, and generate GS1 Digital Links at no cost, with no sign-up required.
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