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. We make this metadata openly available via our APIs, which means people and machines can incorporate it in their research tools and services. Learn more about the metadata each member is depositing with us using our Participation Reports (beta).
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.
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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.
There are interfaces for people (to look up small numbers of DOIs): Metadata Search, and Simple Text Query.
There are APIs for machines (to look up metadata records or DOIs in volume), including: REST API, XML API, OAI-PMH, and OpenURL; and our paid Metadata Plus service.
Take a look at a list of some of the organizations who rely on our REST API.
Here is a comparison of the metadata retrieval options:
| 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 | Machines | Machines | Machines | Machines |
| Output format | Text, JSON | Text | JSON | XML | XML | XML | JSON, XML |
| Suitable for citation matching? | Yes (low volume) | Yes | Yes | Yes | No | No | Yes |
| Supports volume downloads? | No | No | Yes | No | Yes | No | Yes |
| Suitable for usage type | Frequent and occasional | Frequent and occasional | Frequent and occasional | Frequent | Frequent | Frequent | Frequent and occasional |
| Free or cost? | Free | Free | Free and cost options | Free and cost options | Cost for full service, more options available | Free but requires an account | Cost |
| Includes all available metadata? | In JSON only | DOIs only | Yes | Yes | Yes | Bibliographic only | Yes |
| Documentation | Metadata Search | Simple Text Query | REST API | XML API | OAI-PMH | OpenURL | Metadata Plus (OAI-PMH + REST API) |
If you’d like to share a case study for how you use Crossref metadata, and be featured on our blog, please contact us.
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.
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].
All of our metadata is freely available, but there is a fee for our premium Metadata Plus service.
Crossref provides a number of user interfaces to access Crossref metadata. Some are general-purpose, and others are more specialized.
| Service name | Description |
|---|---|
| Metadata Search | 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 | 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. |
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.
| API name | Description |
|---|---|
| REST API | The REST API outputs in JSON and enables sophisticated, flexible machine and programmatic access to search and filter our metadata. It can be used, for example, to look up the metadata for a content item or submit a query on an author’s name or find retractions registered with us. It also allows users to search and filter on a number of elements, including a funder, or all content items with ORCID iDs. The REST API is open to all and it is included in the Metadata Plus service. |
| OpenURL | 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. |
| OAI-PMH | 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. |
| XML API | The XML API supports XML-formatted querying. The XML API is optimized to return the best fit DOI based on the metadata supplied in the query. |
Download the metadata retrieval factsheet, and explore factsheets for other Crossref services and in different languages.
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.
Learn more about metadata retrieval in our Education documentation.
