Why the IIIF Change Discovery API
The International Image Interoperability Framework (IIIF) is a set of open standards for delivering high-quality, attributed digital objects online, designed with cultural institutions in mind. The Europeana Initiative has worked on adopting and promoting IIIF for several years. One of the most recent additions to the IIIF set of standards is the IIIF Change Discovery API, which allows providers to describe changes to IIIF content resources and the location of those resources. This supports the collaborative development of global or thematic search engines and portal applications, like the Europeana.eu website, which ultimately allow users to easily find and engage with IIIF content.
IIIF Change Discovery provides similar functionality to the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH), but it is focused on IIIF content resources and is based on linked data and W3C standards such as JSON-LD and Activity Streams. For cultural institutions that provide metadata to the data space for cultural heritage, the implementation of IIIF Change Discovery provides an alternative to implementing OAI-PMH.
Aggregation pilot with a sports heritage dataset from the Czech Olympic Committee
In 2025, the Europeana Foundation and the Czech Olympic Committee collaborated on an aggregation pilot that tested the implementation of metadata exchange using IIIF Change Discovery.
In recent years, the Czech Olympic Committee has begun making its collections of sports heritage materials available via IIIF. To further increase their visibility and accessibility, it decided to share these collections through the data space as well. IIIF Change Discovery offered a standardised way to do so.
Since the release of IIIF Change Discovery, Europeana has been exploring its potential as one of the supported technical solutions for receiving metadata from partners. The Czech Olympic Committee’s work with IIIF provided the first opportunity to apply this approach in practice.
Pilot outcomes
The pilot demonstrated that the IIIF Change Discovery API could be successfully deployed.
The Czech Olympic Committee made its IIIF Change Discovery endpoint publicly available. A client may access the dataset using its IIIF Change Discovery entry point. Meanwhile, the Europeana Foundation developed a IIIF Change Discovery client and integrated it into Metis, its data ingestion system.
The pilot focused on a collection of photographs from the Czech Olympic Committee collections. Those were harvested via IIIF Change Discovery, processed in Metis, and are now accessible through Europeana.eu.
How is IIIF Change Discovery used for aggregation of EDM metadata
Going into more detail about the aggregation process, the IIIF Change Discovery mechanism enables an aggregator to identify all IIIF Manifests, which represent the objects within a dataset, as well as to detect when manifests are added, updated, or deleted.This uses a representation of lists of activities such as the one below:
{ "type": "Create",
"object": { "id": "https://example.org/library/iiif/book1/manifest",
"type": "Manifest"
},
"endTime": "2025-09-20T00:00:00Z" }
A key requirement for successful aggregation is the availability of metadata describing the IIIF resources in the Europeana Data Model (EDM). Data providers should make their EDM metadata accessible through the IIIF Manifest, using one of the linking properties defined by IIIF: the seeAlso property.
Each IIIF Manifest must include a seeAlso reference pointing to the corresponding EDM metadata record. This reference should explicitly indicate that the record conforms to EDM and should have the type Dataset. In IIIF, any seeAlso resource intended for machine processing, including single files, must be tagged as a Dataset.
An example is provided below:
{ …
"id": "https://example.org/library/iiif/book1/manifest" “type” : “Manifest” ,
“seeAlso” : [ {
"id": "https://example.org/library/catalog/book1.rdf",
"type": "Dataset",
"label": {
"en": \[ "Bibliographic description of a book in EDM"\]
},
"format": "application/rdf+xml",
"profile": "http://www.europeana.eu/schemas/edm/"
}
] …
}
IIIF Change Discovery endpoints can contain other resources besides IIIF Manifests (for example, IIIF Collections), these additional resources will not affect the aggregation process, as they are ignored by the aggregator.
Looking to the future
This pilot confirmed that IIIF Change Discovery is a viable method for providing datasets to the data space. The API is now supported by Metis, so any data partner can use this approach to deliver collections.
Next, Europeana Foundation will integrate its IIIF Change Discovery client into the Metis Sandbox, enabling partners to test their own implementations of IIIF Change Discovery, verify the results and proceed with their submission for publication into the Europeana website.
If you have collections published using IIIF and would like to experiment with IIIF Change Discovery to have them harvested into Europeana, please contact us!