Examples
Worked examples
- Is an instance
A tweet linking to a journal article's DOI was captured as an event with the tweet as the source, the article's DOI as the subject, and a timestamp -- this record was retrievable via the Event Data API and was one of the inputs altmetrics aggregators such as Altmetric or PlumX Metrics could draw on to help calculate an attention score for that article.
- Is an instance
A Wikipedia article citing a paper by its DOI in its references list generated a Wikipedia-source event, distinct from a news article or blog post referencing the same DOI -- Event Data classified events by source type so downstream tools could weight or filter by where the mention occurred.
Counter-examples
Looks similar, but isn't
- Not an instance
A citation from one peer-reviewed journal article to another, captured in Crossref's standard reference-linking metadata, was not an Event Data record -- formal scholarly citations are tracked through Crossref's citation/reference deposit and matching infrastructure, not through Event Data, which was scoped specifically to non-traditional, web-based mentions outside the formal citation graph.
- Not an instance
A dataset citation captured through Crossref members' own deposited metadata relationships (references between an article and a dataset) is now surfaced through Crossref's dedicated data-citation API endpoint introduced as part of the Event Data sunset -- this is a narrower, metadata-deposit-based mechanism, not a revival of Event Data's broader web-crawling/mention-tracking model.
Editorial commentary
Crossref Event Data was a free Crossref service, launched in 2016, that captured “events” — structured records of online activity referencing a piece of scholarly content by its DOI. An event could be a tweet linking to an article, a Wikipedia page citing a paper in its references, a newspaper article mentioning a DOI, a blog post, or an annotation on a preprint. Each record linked a source, a subject DOI, and a timestamp, and the aggregated data was made available through a public API that third-party altmetrics tools and dashboards could query and build on.
Status: discontinued. Crossref sunset Event Data on 23 April 2026 — the public API and supporting infrastructure are no longer available. Crossref’s own announcement cited relatively low usage of the service relative to the cost of maintaining it, and framed the decision as part of a broader shift in priority toward transparency, research-integrity signals, and completeness of Crossref’s core metadata rather than toward standalone mention-tracking. Historical Event Data collected before the sunset remains accessible on request, and Crossref has said a full data repository of everything Event Data collected can be requested from its support team, but no new events have been (or will be) captured since the sunset date. Content discussing Event Data as a live, queryable service is now describing a discontinued product; current material should reflect past-tense operation.
What Event Data actually tracked
Event Data classified mentions by source type so downstream consumers could filter or weight them differently — social media (originally Twitter/X, among others), Wikipedia, mainstream and trade news outlets, blogs (via services like WordPress.com and Disqus integrations), and post-publication annotation/commenting platforms such as Hypothesis. This is the same conceptual territory covered by the broader altmetrics field: rather than counting formal scholarly citations, it counted evidence that a research output was being discussed, shared, or referenced outside the peer-reviewed literature. Event Data itself did not calculate an attention score or ranking — it supplied the raw, DOI-linked event records; scoring and weighting were left to the tools that consumed the feed, such as Altmetric Explorer and PlumX Metrics.
Why it was discontinued
Crossref’s public explanation for the sunset centered on usage: the service saw comparatively low direct use for the ongoing engineering and infrastructure cost of running it, and Crossref chose to redirect that investment toward strengthening data-citation support within its core metadata deposit and retrieval systems instead of maintaining Event Data as a separate, standalone product. This is consistent with a pattern of periodic service consolidation at Crossref as it has prioritized core registration-agency functions (DOI registration, metadata deposit, citation linking) over adjacent value-added services with narrower adoption.
What replaced it
Crossref did not replace Event Data’s broad web-mention-tracking model with an equivalent successor. Instead, it introduced a narrower, dedicated API endpoint focused specifically on data citations — surfacing the citation relationships between articles and datasets that Crossref members already deposit as structured reference metadata, rather than crawling the open web for DOI mentions. This means organizations that relied on Event Data purely for formal data-citation discovery have a more targeted (if narrower-scope) Crossref-native alternative; organizations that relied on it for broader altmetrics signal (social media, news, Wikipedia mentions) need to look to commercial or third-party altmetrics providers that maintain their own independent mention-tracking infrastructure, since that functionality no longer has a Crossref-operated source feed.
Practical implications for research administrators
Anyone maintaining documentation, data-management-plan templates, or research-metrics workflows that cite Event Data as a live data source should update those references: any pipeline, dashboard, or grant report that pointed at the Event Data API directly is now broken and needs to be repointed at a still-supported altmetrics provider or at Crossref’s data-citation endpoint, depending on which functionality was actually being used. Historical event records remain available on request rather than through the live API, which matters for anyone needing pre-2026 mention data for a retrospective analysis rather than an ongoing feed.
References
- Crossref, “Strengthening support for data citations and saying goodbye to Event Data,” crossref.org/blog.
- Crossref, “This tool is no longer available,” crossref.org/deprecated/.
- Crossref, Event Data User Guide, eventdata.crossref.org/guide.
Machine-readable encodings
Use in your systems
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