Research doesn’t stand alone and relationships show the connections between research outputs, people, and organizations. We deliver these connections via a relationships API endpoint, which makes the Research Nexus visible.

Relationships show how items are related to each other. A published research article may be supported by data, software, and peer reviews; previous versions might be available as a preprint and there could be online commentary and annotations. Research is reused and cited in other research works, as well as being mentioned in online venues such as blog posts and news articles. The relationships endpoint makes all of these connections available in a single place.

We collect relationships from a number of sources:

  • Metadata deposited by our members
  • Links we discover between existing metadata records, for example, through reference matching.
  • Event Data agents
  • Trusted community partners, such as DataCite and Retaction Watch.

The relationships endpoint is the successor to the Event Data API, which focused on sources external to Crossref. Incorporating events into the new endpoint puts them alongside other relationship types, so users have a more comprehensive view from a single location.

How does the relationships endpoint work?

We collect metadata from our members, Event Data, and selected other sources. When we find a connection between two items (a research output, organization, or person), we represent it as a relationship with the following information:

  • Subject (source of the relationship)
  • Object (target of the relationship)
  • Relationship type

We also provide metadata about when the relationship was last updated and which organizations deposited metadata about the relationship.

You can access the results in JSON format from our REST API.

Query filters are available to look for specific items, types of items, types or relationships, time ranges, and source organizations. For a full range of queries see the Swagger documentation.

Who are relationships for?

There are a range of applications for relationships, and probably plenty that we haven’t thought of! The API is open for anyone to access. Those who currently use the Event Data API should switch to the relationships endpoint. Here are a few examples:

Relationships are provided via a freely available public API. This makes it suitable for post-processing and creating downstream tools such as search interfaces or dashboards. We do not curate the metadata we receive or provide plugins and data analytics.

Note that counts of references are based on our member metadata and differ from other services; see this Community Forum post for further background.

Page owner: Martyn Rittman   |   Last updated 2023-October-10