GS1 Digital Link and JSON-LD: The Technical Standards Behind EU DPP

The EU Digital Product Passport is not a PDF file. It is not a QR code pointing to a marketing landing page. It is a machine-readable, standards-based, interoperable data payload that must be accessible to consumers, customs authorities, recyclers, market surveillance bodies, and AI agents — all through a single identifier on a single data carrier.

Two technical standards form the backbone of this architecture: GS1 Digital Link for the identifier and routing layer, and JSON-LD for the data payload and semantic interoperability. Understanding how these standards work together is essential for any technical team building DPP infrastructure.

This article provides a technical deep-dive into both standards, the CEN/CLC JTC 24 standards under development, and the implementation requirements for textile brands.

GS1 Digital Link: The Universal Product Identifier

GS1 Digital Link (formally defined in GS1 General Specifications v23, 2024) solves a fundamental problem: how does a single barcode or RFID tag serve retail point-of-sale, consumer engagement, regulatory verification, and recycling sortation — all simultaneously?

The answer is a structured HTTP URI that encodes GS1 Application Identifiers (AIs) into web-resolvable path segments. Here is the standard structure:

https://id.brand.com/01/09506000134352/21/SERIAL-2026-K78/10/BATCH-Q2-YARN27

Breaking this down:

Why This Matters for DPP

The traditional approach — printing a GTIN barcode for retail scanning plus a separate QR code for consumer engagement plus a separate web URL for regulators — creates three different identifiers for the same product. This fragmentation breaks traceability, complicates authentication, and violates the ESPR principle of a “single source of truth.”

GS1 Digital Link replaces all three with one URI that adapts to the scanning context:

[QR Scanner / Smartphone Camera / NFC Reader / RFID Portal]
                       │
                       ▼
 [Resolver at https://id.brand.com/01/GTIN/21/SERIAL]
                       │
         ┌─────────────┼─────────────┬──────────────────┐
         ▼             ▼             ▼                  ▼
  Accept: text/html  Accept:        GS1 Source: POS  X-Auth-Key:
  → Consumer web     application/   → Inventory       regulator
    portal with       ld+json →      system            → Full audit
    product story     DPP data       (retailer)         trail
                      payload

[!IMPORTANT]

Browser Accept header negotiation is not optional. Your resolver must inspect the HTTP Accept header and respond with text/html for browsers (consumers), application/ld+json for machines (regulators, recyclers, AI agents), and application/json as a fallback. The ESPR compliance verification robots will request application/ld+json and expect a valid JSON-LD document within 200 milliseconds. A 302 redirect to a consumer marketing page when JSON-LD is requested is a compliance failure.

The ISO/IEC 18975:2024 Standard

GS1 Digital Link is now codified as ISO/IEC 18975:2024, “Automatic identification and data capture techniques — GS1 Digital Link.” This ISO ratification gives the standard legal standing within the EU regulatory framework and ensures that the specification is maintained through an open, consensus-based process rather than a single commercial entity.

JSON-LD: Structuring the DPP Data Payload

JSON-LD (JavaScript Object Notation for Linked Data, W3C Recommendation, 2020) is the data serialization format selected by the European Commission for DPP data exchange. Unlike plain JSON, JSON-LD adds semantic context — each field is explicitly linked to a globally defined meaning — enabling true interoperability between systems that may have been developed independently.

The Anatomy of a JSON-LD DPP Payload

{
  "@context": [
    "https://schema.org",
    "https://gs1.org/voc/",
    "https://dpptex.com/contexts/dpp-textile-v1.jsonld"
  ],
  "@type": "Product",
  "@id": "https://id.brand.com/01/09506000134352/21/SERIAL-2026-K78",
  "gtin14": "09506000134352",
  "serialNumber": "SERIAL-2026-K78",
  "batchNumber": "BATCH-Q2-YARN27",
  "name": "Circular Wool Blend Overshirt",
  "description": "70% recycled wool, 30% TENCEL Lyocell",
  "manufacturer": {
    "@type": "Organization",
    "name": "Nordic Circular Textiles AB",
    "location": {
      "@type": "Place",
      "address": {
        "@type": "PostalAddress",
        "addressCountry": "SE"
      }
    }
  },
  "countryOfOrigin": {
    "@type": "Country",
    "name": "Portugal"
  },
  "material": {
    "@type": "Product",
    "materialComposition": [
      {
        "@type": "TextileMaterial",
        "name": "Recycled Wool",
        "percentageComposition": 70,
        "recycledContent": 100,
        "certification": "GRS-2025-TE-004782"
      },
      {
        "@type": "TextileMaterial",
        "name": "TENCEL Lyocell",
        "percentageComposition": 30,
        "certification": "Lenzing-2025-LY-1273"
      }
    ]
  },
  "sustainability": {
    "@type": "SustainabilityRating",
    "carbonFootprint": {
      "@type": "QuantitativeValue",
      "value": 8.4,
      "unitCode": "KGM",
      "unitText": "kg CO2e per kg product"
    },
    "waterFootprint": {
      "@type": "QuantitativeValue",
      "value": 2850,
      "unitCode": "LTR",
      "unitText": "litres per kg product"
    },
    "durabilityWashIndex": 78,
    "recyclabilityScore": 92
  },
  "hasGS1DigitalLink": "https://id.brand.com/01/09506000134352/21/SERIAL-2026-K78",
  "productionDate": "2026-03-15",
  "discontinuedDate": null
}

Key JSON-LD Properties and Their DPP Relevance

Why JSON-LD and Not Plain JSON or XML?

The European Commission evaluated three data serialization formats during the 2024-2025 technical committee process:

The critical advantage of JSON-LD is that a single document can be simultaneously:

• Human-readable (viewed as formatted JSON in any browser)
• Machine-readable (semantic context allows AI agents to understand the meaning of each field)
• Web-resolvable (every field can link to a definitional URI)
• Search engine indexable (Google, Bing, and other search engines natively parse JSON-LD embedded in product pages via Schema.org markup)

CEN/CLC JTC 24: The 8 Standards in Development

The EU has mandated CEN and CENELEC (the European Committee for Standardization and the European Committee for Electrotechnical Standardization) to develop the full suite of technical standards for DPP through Joint Technical Committee 24 (JTC 24). Eight standards are currently in development:

[!TIP]

The March 2026 target is a working assumption, not a hard legal deadline. CEN/CLC JTC 24 standards are published as “European Norm” documents and must be transposed into national standards by all EU/EEA member states. Brands should aim for compliance with the final drafts by Q2 2026, but formal certification will be assessed against the published EN versions. Follow the CEN/CLC JTC 24 work programme on the CEN website for real-time publication updates.

The hasGS1DigitalLink Property and Schema.org Integration

A significant development for the DPP ecosystem is the proposed integration of the hasGS1DigitalLink property into the Schema.org vocabulary. GS1 and Schema.org have been collaborating through a dedicated working group to add this property to the Schema.org Product type.

When adopted, this will enable:

1. Search engine DPP discovery: Google, Bing, and other search engines will automatically discover and index DPP data embedded in product pages via Schema.org markup.
2. Automatic AI agent resolution: AI assistants (GPT, Claude, Gemini) parsing a product page will identify the hasGS1DigitalLink property and resolve it to fetch the full DPP data payload — enabling automated sustainability product comparisons.
3. Unified data ecosystem: Brands that already publish Schema.org product markup will extend (not replace) their existing implementation to include the DPP identifier.

What DPP Is NOT: Common Misconceptions

[!IMPORTANT]

DPP data is NOT a PDF document. The ESPR technical annex explicitly requires machine-readable data. A PDF that describes a product’s carbon footprint, chemical composition, and recyclability is useful for human auditors but invisible to AI agents, customs verification bots, and automated recycling sortation systems. The DPP must return structured JSON-LD — and the EU Market Surveillance Regulation gives automated verification systems the authority to reject PDF-based passport “data” as non-compliant.

Additional misconceptions:

• DPP data is NOT hosted on a government server. The EU registry stores only identifiers, linkages, and verification keys. Actual product data is hosted by the manufacturer or a DPP service provider.
• DPP data is NOT static. Passport data must be updatable throughout the product lifecycle. A material batch change, a product recall, or a revised carbon footprint calculation must update the passport record.
• DPP is NOT just for new products. By 2029, second-hand and vintage products resold within the EU may require retrospective DPP attachment under the proposed Waste Framework Directive amendments.

Actionable Takeaways

1. Register your resolver domain now. Every GS1 Digital Link requires a DNS-controlled, SSL-terminated domain (e.g., id.yourbrand.com). Secure this domain in Q2 2026 to ensure it is in place before resolver deployment begins in Q3.

2. Assign GTINs to every product SKU. If you are not already a GS1 member, join your national GS1 Member Organisation and allocate GTIN-14 identifiers for all products. Serialization infrastructure (unit-level uniqueness) should be in place by Q4 2026.

3. Build your JSON-LD DPP template now. Do not wait for the CEN/CLC JTC 24 standards to be finalized. The core data fields (GTIN, serial number, material composition, carbon footprint, manufacturer, country of origin) are stable. Build the template with these fields and extend as additional standards are published.

4. Implement content negotiation on your resolver. Your GS1 Digital Link resolver must respond to three Accept header types: text/html (browser), application/ld+json (machine), application/json (fallback). Test with curl -H "Accept: application/ld+json" to verify.

5. Deploy a CDN with sub-100ms response time. The ESPR verification robots expect DPP resolver responses within 200ms. A global CDN (Cloudflare, Fastly, Akamai) in front of your resolver is a practical necessity, not a luxury.

6. Do NOT embed PDFs. If your current “DPP” implementation consists of a QR code that downloads a PDF, you are not compliant. Migrate to a JSON-LD payload now. The compliance window is closing.

Sources: GS1 General Specifications v23 (2024); GS1 Digital Link Standard v1.4; ISO/IEC 18975:2024; W3C JSON-LD 1.1 Recommendation (2020); Schema.org Product Type Documentation; CEN/CLC JTC 24 Work Programme (2025-2026); EU ESPR Regulation (EU) 2024/1781, Article 31 and Annex III; GS1-Schema.org Collaboration Working Group on hasGS1DigitalLink Property (2025-2026); European Commission JRC Technical Report on DPP Data Architecture (February 2026).

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📚 Regulatory & Academic Bibliography

• European Commission - ESPR Guidelines: Official EUR-Lex circular economy directives and delegated acts.
• GS1 Global Standards Registry: Technical specifications for GTIN-14 and resolver architectures.
• W3C Verifiable Credentials Core 2.0: Cryptographic verification protocols and JSON-LD syntax rules.
• ISO Quality Management Systems Catalog: Forensic laboratory and testing competence requirements (ISO 17025).