How do QR codes and GS1 Digital Link connect a product to its passport?
What a GS1 Digital Link is, how a scan finds the right passport, and how batches and serial numbers change the answer.
DPP Shield editorial team · Updated:
A GS1 Digital Link is a web address that encodes a product's GS1 identifiers - its GTIN, and optionally a batch or serial number - in a standard path such as /01/{GTIN}/10/{batch}/21/{serial}. Printed as a QR code, it opens like any link on a phone, while a resolver uses the identifiers in the path to return the passport for that exact product, batch or item.
What is a GS1 Digital Link?
GS1 identifiers such as the Global Trade Item Number (GTIN) have been printed in barcodes for decades. The GS1 Digital Link standard expresses the same identifiers as a URL, so one code can serve both a checkout scanner and a smartphone camera.
Each identifier has an application identifier: 01 for the GTIN, 10 for the batch or lot, 21 for the serial number. The standard fixes their order in the path, which is why the same item always produces the same address.
How does a scan find the right passport?
The code points at a resolver: a service that reads the identifiers in the path and answers with the right destination. For a GTIN alone it returns the product-level passport; with a batch it narrows to that batch; with a serial number it returns the record for that single item.
A resolver can also answer with a linkset: a machine-readable list of everything it holds for the identifier, such as the passport, sustainability information, traceability data or a recall notice. Tools request it with the header Accept: application/linkset+json or the parameter linkType=linkset.
Why does GTIN ownership matter?
A GTIN is only meaningful because its company prefix was licensed by GS1 to one company. If a resolver accepted any organization's claim to any GTIN, another party could publish a passport for someone else's product and receive its scans.
This platform lets only one organization hold a GTIN, and in production requires the GTIN to fall under a GS1 company prefix the organization has verified. When two claims cannot be decided, resolution is withheld rather than guessed.
Should you encode batches and serial numbers?
It depends on what the product rules require and what differs between units. A batch-level link lets you publish production-specific data and recall one batch without affecting others. A serial-level link supports item-level records, such as a battery's state of health or its repair history.
The finer the identifier, the more records you maintain. Start with the level the applicable rules require, and make sure the label printing process encodes exactly the batch and serial that the passport records.
What should the QR code itself look like?
Encode the Digital Link URL, not an internal page address, so the code keeps working if the platform or its URLs change. Leave a quiet zone around the symbol, print it at a size that scans on a phone at arm's length, and test the printed label - not only the file - before production.