> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://tieback.io/docs/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://tieback.io/docs/_mcp/server. # Resolver > A service that answers a request for an identifier-bearing address and returns the linked resource appropriate to the requester. ## Definition In the product identity context used across tieback Knowledge, a resolver is a service that receives a request for a web address containing a product identifier and returns, or redirects to, the linked resource appropriate to that request. The term is also used for unrelated services in networking and software; this entry does not describe those. ## Expanded Explanation The pattern is a short chain. An identifier is expressed inside a URI, typically under [GS1 Digital Link](/docs/knowledge-base/glossary/gs1-digital-link) and carried by a [data carrier](/docs/knowledge-base/glossary/data-carrier). Scanning the carrier produces a resolution request. The resolver looks up the identifier, decides which destination applies, and returns one or more linked resources or services. Resolution is not the same as redirection, although it usually ends in one. A redirect is a single fixed hop. Resolution is a lookup against a set of entries held for that identifier, each described by a link type such as product information, instructions, safety data, certification or a passport endpoint. Because the entries are data rather than print, destinations can be added, changed or retired without altering anything already applied to a product. The same identifier can therefore have several legitimate destinations at once. A consumer, a repairer, a recycler and an authority may be routed to different resources from one scan, and a machine client can request the list of available links rather than a rendered page, which is what makes the mechanism usable by software as well as by people. Two operational properties matter more than the technology. Persistence: identifiers printed on products outlive websites, content restructures and system migrations, so the resolution address needs to be treated as long-lived infrastructure. Availability: if the resolving domain or service is unreachable, every carrier pointing at it fails at once, which is why the choice of who operates resolution (the brand owner, a service provider, or an industry body) is a governance decision rather than a purely technical one. ## Why It Matters Resolution is the layer that decouples what is printed on a product from where the information lives. Implementations that skip it and encode a destination URL directly are committing to that URL for the life of the product, and the cost of being wrong is reprinting or relabelling rather than editing a record. ## Relationship to Digital Product Passports Where a passport must be reachable from the product, something has to turn a scan into the correct passport view for the party doing the scanning, and to keep doing so as content, systems and access rules change. That is the job a resolver performs. The requirement is that the passport be accessible through the carrier and identifier; the resolver is a well-established means of meeting it, not a legally named component. ## Common Misconceptions #### The resolver is the passport, or the product database A resolver holds links, not content. The passport and the underlying product records are separate systems that resolution points at. #### The resolver is the identifier or the carrier The identifier is the key, the carrier delivers it, and the resolver answers requests for it. Conflating the three is the most common source of confusion in this area. #### There is one central resolver everyone must use Resolution is distributed. Organisations can operate their own resolution service, use a provider or use one offered by an industry body, and standards conformance does not depend on choosing any particular operator. ## Related Terms * [GS1 Digital Link](/docs/knowledge-base/glossary/gs1-digital-link) * [Data Carrier](/docs/knowledge-base/glossary/data-carrier) * [Product Identifier](/docs/knowledge-base/glossary/product-identifier) * [QR Code](/docs/knowledge-base/glossary/qr-code) * [GTIN](/docs/knowledge-base/glossary/gtin) * [Digital Product Passport](/docs/knowledge-base/glossary/digital-product-passport) ## Related Knowledge Base Articles * [What is GS1 Digital Link?](/docs/knowledge-base/standards-and-technology/what-is-gs1-digital-link) * [QR Codes vs GS1 Digital Link: What's the Difference?](/docs/knowledge-base/standards-and-technology/qr-codes-vs-gs1-digital-link) * [How Does a Digital Product Passport Work?](/docs/knowledge-base/digital-product-passports/how-does-a-digital-product-passport-work) ## Related Articles * [GS1 Digital Link](/docs/knowledge-base/glossary/gs1-digital-link) * [GS1](/docs/knowledge-base/glossary/gs1) * [GTIN](/docs/knowledge-base/glossary/gtin) * [Data Carrier](/docs/knowledge-base/glossary/data-carrier) * [EPCIS](/docs/knowledge-base/glossary/epcis) * [Harmonised Technical Specification](/docs/knowledge-base/glossary/harmonised-technical-specification) * [Product Identifier](/docs/knowledge-base/glossary/product-identifier) * [QR Code](/docs/knowledge-base/glossary/qr-code) ## See Also * [Standards & Technology](/docs/knowledge-base/standards-and-technology/overview) * [Digital Product Passports](/docs/knowledge-base/digital-product-passports/overview) ## References * GS1 Digital Link standard: [https://www.gs1.org/standards/gs1-digital-link](https://www.gs1.org/standards/gs1-digital-link) * GS1, identification keys: [https://www.gs1.org/standards/id-keys](https://www.gs1.org/standards/id-keys) * GS1 web vocabulary: [https://www.gs1.org/voc/](https://www.gs1.org/voc/) * Regulation (EU) 2024/1781 establishing a framework for ecodesign requirements: [https://eur-lex.europa.eu/eli/reg/2024/1781/oj](https://eur-lex.europa.eu/eli/reg/2024/1781/oj) ## About This Article About This Article
Last Reviewed
2026-08-09
Next Scheduled Review
2027-08-09
Article Version
1.0
tieback Knowledge is a continuously maintained reference library covering Digital Product Passports, product traceability, product compliance and related regulations. Articles are reviewed regularly as legislation, standards and implementation guidance evolve. ## Related Docs * [Standards & Technology](/docs/knowledge-base/standards-and-technology/overview) * [Digital Product Passports](/docs/knowledge-base/digital-product-passports/overview) * [Glossary](/docs/knowledge-base/glossary/overview)