To date, we have collected around 740 million events from 12 different source since we launched our Event Data service service in 2017. Each event is an online mention of the research associated with a DOI, either via the DOI directly or using the associated URL. However, we know that there is much more out there. Because of this, we would like to explore where we could expand.
We invite proposals to conduct a gap analysis for Event Data sources, looking at what we currently collect and seeing what more could be added.
We are delighted to announce the formation of a new Advisory Group to support us in improving preprint metadata. Preprints have grown in popularity over the last few years, with increasing focus brought by the need to rapidly disseminate knowledge in the midst of a global pandemic. We have supported metadata deposits for preprints under the content type ‘posted content’ since 2016, and members currently register a total of around 17,000 new preprints metadata records each month.
It is time to put the ‘R’ back into R&D.
The Crossref R&D team was originally created to focus on the kinds of research projects that have allowed Crossref to make transformational technology changes, launch innovative new services, and engage with entirely new constituencies. Some Illustrious projects that had their origins in the R&D group include:
DOI Content Negotiation Similarity Check (originally CrossCheck) ORCID (originally Author DOIs) Crossmark The Open Funder Registry The Crossref REST API Linked Clinical Trials Event Data Grant registration ROR And for each project that has graduated, there have been several that have not.
This announcement has been in the works for some time, but everything seems to take longer when there is a pandemic going on, including finding time and headspace to plan out our strategy for the next few years.
Over the last year or so we have had our heads down addressing how to scale our 20-yr-old system and operation – and adapting to new ways of working. But we’ve also spent time talking to people, forging alliances, looking ahead, and making plans.
The collective power of our members’ metadata is available to use through a variety of tools and APIs—allowing anyone to search and reuse the metadata in sophisticated ways.
Members register content with us to let the world know it exists. They send us information called metadata which we collect and store in a standard way. The metadata includes a Digital Object Identifier (DOI) in each record, which links to the content even if it moves to a new website. We make this metadata openly available via our APIs, which means people and machines can incorporate it in their research tools and services. Metadata does not include the full-text of the content itself. While we collect and distribute metadata, we do not change members' metadata. Learn more about the metadata each member is depositing with us using our Participation Reports.
Manuscript tracking services, search services, bibliographic management software, library systems, author profiling tools, specialist subject databases, scholarly sharing networks - all of these (and more) incorporate scholarly metadata into their software and services. They use our free APIs to help them get the most complete, up-to-date set of metadata from all of our publisher members. And of course, members themselves are able to use our free APIs too.
Watch the introductory animation in your language:
To retrieve metadata from Crossref, you do not need to be a member. We have various options for retrieving metadata - some are more suitable for human use, and some for machine use.
Here is a comparison of the metadata retrieval options. Please note that all interfaces include Crossref test prefixes: 10.13003, 10.13039, 10.18810, 10.32013, 10.50505, 10.5555, 10.88888.
Feature / option
Metadata Search
Simple Text Query
REST API
XML API
OAI-PMH
OpenURL
Metadata Plus (OAI-PMH + REST API)
Interface for people or machines?
People
People
People (low volume and occasional use) and machines
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.
Crossref generally provides metadata without restriction; however, some abstracts contained in the metadata may be subject to copyright by publishers or authors.
How to participate - interfaces for people
Crossref provides a number of user interfaces to access Crossref metadata. Some are general-purpose, and others are more specialized.
Metadata Search is our primary user interface for searching and filtering of our metadata. It can be used to look up the DOI for a reference or a partial reference or a set of references, to look up metadata for a content item, submit a query on an author’s name, or find retractions registered with us. It can also be used to search and filter a number of elements, including funding data, ISSN, ORCID iDs, and more.
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 lets you look up a Crossref DOI for a reference, using a standard that is popular in the library community, and particularly with link resolver services.
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.
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.
User interfaces
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.
APIs
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)
Deposit harvester - retrieve DOIs and metadata for a given member (members only).
