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EnglishWhat Is Crossref and What Does It Do?
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Crossref is an open infrastructure organization that links research outputs by registering persistent identifiers and openly sharing the associated metadata. It is best understood as the connective layer behind scholarly publishing: publishers register content and metadata with Crossref, and that metadata is then distributed through free APIs so that tools, services, and researchers can find, link, and assess scholarly work. The site describes Crossref as linking the world's research, with more than 26,000 members across 167 countries and roughly 2.1 billion monthly API queries.
The Core Mechanism: Registration Plus Open Metadata
Crossref's model rests on two connected activities.
Content registration. Members register records for their publications. According to Crossref's blog, members register around 37,000 records daily. Registration is what creates the persistent links and identifiers that let one work reliably point to another.
Metadata retrieval and sharing. All of that registered metadata is openly shared with the global scholarly community through Crossref's free APIs. This is the part most people encounter indirectly: reference linking, citation matching, and discovery tools all draw on this shared metadata pool.
The scale figures matter because they explain why Crossref is useful. A linking system only works if enough publishers participate, and a metadata service is only valuable if it covers a large share of the literature. Crossref's member count and query volume indicate both conditions are broadly met.
What Services Does Crossref Provide?
The site organizes its offerings under a "Find a service" menu. The main services include:
| Service | What it does |
|---|---|
| Content Registration | Members register their records with Crossref |
| Metadata Retrieval | Access registered metadata, including through APIs |
| Metadata Plus | A service tier for metadata access |
| Grant Linking System (GLS) | Linking infrastructure for grants |
| Research Organization Registry (ROR) | Registry of research organizations |
| Open Funder Registry (OFR) | Registry of funders |
| Support for Reference Linking | Infrastructure for linking citations |
| Similarity Check | Similarity screening service |
| Cited-by | Linking and display of citation relationships |
| Crossmark | A record-update indicator for published content |
These services share a common purpose: making scholarly objects identifiable, linkable, and checkable. For example, a publisher wanting its references to resolve reliably would use reference linking; a tool builder wanting to enrich bibliographic data from PDFs would draw on the metadata APIs.
Who Uses Crossref, and How?
Crossref's users fall into a few practical groups.
Publishers and members register content and maintain their records. Membership is the route to registration, and the site provides documentation on setting up as a member and on metadata principles and practices.
Tool builders and developers consume the APIs. Crossref's blog highlights this ecosystem directly: in a post about Grobid, a tool for extracting bibliographic information from scholarly PDFs, the developer explains how Grobid uses Crossref metadata to improve extraction and enrichment. The post notes that Crossref's metadata supports hundreds of tools and services worldwide. This is a concrete example of the infrastructure role: Crossref does not build every discovery tool, but it supplies the shared metadata those tools depend on.
Researchers and readers benefit indirectly, through reference links, citation displays, and record-status indicators such as Crossmark.
Documentation and Getting Started
Crossref maintains a documentation section covering setting up as a member, metadata principles and practices, registering and maintaining records, a schema library, and reports. There are also dedicated documentation areas for Crossmark, Cited-by, Similarity Check, and Metadata Retrieval.
If you are evaluating Crossref for a specific task, the practical path is to identify which service matches your need, then read that service's documentation. A publisher registering DOIs and metadata starts with membership setup and content registration; a developer building a tool starts with the metadata retrieval APIs and schema library.
What Crossref Is Not
Two boundaries are worth stating plainly. First, Crossref is an infrastructure and metadata organization, not a publisher or a database of full texts; its role is registration, linking, and metadata sharing. Second, the site does not present public pricing for membership or services in the material available here. Fee information exists under a "Fees" menu item, but no amounts are stated in the source, so cost should be confirmed directly rather than assumed to be free or fixed.
For a quick orientation: Crossref is the registry and linking backbone for scholarly metadata, sustained by member participation and distributed through open APIs. Whether it fits your task depends on whether you need to register content, retrieve metadata, or build on shared scholarly identifiers.