Crossref holds metadata for approximately 150 million scholarly artifacts. These range from peer reviewed journal articles through to scholarly books through to scientific blog posts. In fact, amid such heterogeneity, the only singular factor that unites such items is that they have been assigned a document object identifier (DOI); a unique identification string that can be used to resolve to a resource pertaining to said metadata (often, but not always, a copy of the work identified by the metadata).
We’re equally sad and proud to report that Rachael Lammey is moving on in her career to the very lucky team at 67Bricks. Her last day at Crossref is today, Friday 16th February. Which is too soon for us, but very exciting for her!
It’s hard to overstate Rachael’s impact on Crossref’s growth and success in her 12 years here. She started as a Product Manager where she developed that role into a broad and central function, and soon moved into the newly-formed community team as International Outreach Manager where she grew important programs such as Sponsors, Ambassadors, a series of ‘LIVE’ events around the world, and she went on to manage her own team and establish some of the most important strategic relationships that Crossref now feels fortunate to have.
Great news to share: our Executive Director, Ed Pentz, has been selected as the 2024 recipient of the Miles Conrad Award from the USA’s National Information Standards Organization (NISO). The award is testament to an individual’s lifetime contribution to the information community, and we couldn’t be more delighted that Ed was voted to be this year’s well-deserved recipient.
During the NISO Plus conference this week in Baltimore, USA, Ed accepted his award and delivered the 2024 Miles Conrad lecture, reflecting on how far open scholarly infrastructure has come, and the part he has played in this at Crossref and through numerous other collaborative initiatives.
Metadata about research objects and the relationships between them form the basis of the scholarly record: rich metadata has the potential to provide a richer context for scholarly output, and in particular, can provide trust signals to indicate integrity. Information on who authored a research work, who funded it, which other research works it cites, and whether it was updated, can act as signals of trustworthiness. Crossref provides foundational infrastructure to connect and preserve these records, but the creation of these records is an ongoing and complex community effort.
People using Crossref metadata need it for all sorts of reasons including metaresearch (researchers studying research itself such as through bibliometric analyses), publishing trends (such as finding works from an individual author or reviewer), or incorporation into specific databases (such as for discovery and search or in subject-specific repositories), and many more detailed use cases.
All Crossref metadata is open and available for reuse without restriction. Our
156073294 records include information about research objects like articles, grants and awards, preprints, conference papers, book chapters, datasets, and more. The information covers elements like titles, contributors, descriptions, dates, references, connecting identifiers such as Crossref DOIs, ROR IDs and ORCID iDs, together with all sorts of metadata that helps to determine provenance, trust, and reusability—such as funding, clinical trial, and license information.
If you’d like to share a case study for how you use Crossref metadata, and be featured on our blog, please contact us.
Using content negotiation
The APIs listed here provide metadata in a variety of representations (also known as output formats). If you want to access our metadata in a particular representation (for example, RDF, BibTex, XML, CSL), you can use content negotiation to retrieve the metadata for a DOI in the representation you want. Content negotiation is supported by a number of DOI registration agencies including Crossref, DataCite, and mEDRA.
Obligations and fees for metadata retrieval
It is important that members understand that metadata is used by other software and services in the Crossref community. We encourage members to submit as much metadata as possible so that our APIs can include and deliver rich contextual information about their content.
If you’re using the public REST API, it is optional but encouraged to include your email address in header requests as this puts your query into the “polite” pool which has priority processing. Learn more about our REST API etiquette.
Simple Text Query is a tool designed to allow anyone to look up DOIs for multiple references. As such it’s particularly useful for members who want to link their references. Members can even use this tool to add linked references to their metadata.
How to participate - APIs for machines
We have a number of APIs for accessing metadata. There is one general-purpose API and several specialized ones. The specialized APIs are designed for our members so that they can manage their metadata or they are APIs based on standards that are popular in the community.
This API outputs in XML and uses a standard popular in the library community to harvest metadata. The OAI-PMH API is optimized to return a list of results matching the query parameters (such as publication year). The OAI-PMH API is included in the Metadata Plus service.
While the public data files are not an API, they are freely available bulk downloads of the full Crossref metadata corpus, published annually. It can be downloaded via Academic Torrents, or directly from AWS for a small fee.
We support a range of tools and APIs to help you get metadata (and identifiers) out of our system. Some query interfaces will return only one match, and only if fairly strict requirements are met. These interfaces may be used to populate citations with persistent identifiers. Other interfaces will return a range of results and may be used to retrieve a variety of metadata records or match metadata when metadata, DOIs, or other identifiers (such as ORCID iD, ISSN, ISBN, funder identifier) are provided.
Metadata Search - any results containing the entered search terms will be returned. Search by full citation, title (or fragments of a title), authors, ISSN, ORCID, DOI (to retrieve metadata) and more.
Simple Text Query - cut-and-paste your reference list into the form and retrieve exact DOI matches.
REST API - a RESTful API that supports a wide range of facets and filters. By default, results are returned in JSON, and returning results in XML is an option. This API is currently publicly available (no account or token required), but there is a paid Metadata Plus service available on a token for those who require guaranteed service levels
XML API - the XML API will return a DOI that best fits the metadata supplied in the query. This API is suitable for automated population of citations with DOIs as the results are accurate and do not need evaluation. This API is available to members, or by supplying an email address.
OpenURL - used mostly by libraries but also available to members, or by providing an email address. Learn more about OpenURL access.
OAI-PMH - as well as a free public list option, we provide a subscription-only OAI-PMH interface that may be used to retrieve sets of metadata records (subscribers only)
GetResolvedRefs - retrieve DOIs matched with deposited references (members only)