Crossref
by Crossref · Service · also known as CrossRef, Crossref REST API
Membership organization that registers DOIs for scholarly content and exposes the metadata through a free public REST API, content negotiation and the paid Metadata Plus service
Overview
Crossref is the scholarly DOI registration agency: publishers, societies, universities and funders join as members and register persistent identifiers and metadata for journal articles, books, preprints, datasets, grants and other content, paying tiered annual membership fees and one-time per-record registration fees. The resulting metadata corpus, which the organization states is almost entirely free of copyright restrictions apart from some abstracts, is available to anyone without signup through the REST API at api.crossref.org: /works, /journals, /members, /prefixes, /funders, /types and /licenses endpoints support filtering, faceting, sampling and querying, and content negotiation returns a single record in BibTeX, RIS, CSL JSON and other formats.
API usage is tiered by politeness: adding a mailto parameter places requests in the "polite" pool with better service, back-off is expected on 429 responses, and the paid Metadata Plus subscription provides dedicated capacity and monthly snapshots for heavy users. Reference managers (Zotero, JabRef), OpenAlex and most discovery tools rely on Crossref for DOI lookup and citation metadata. Limits are that coverage depends on what members deposit (reference lists and abstracts are incomplete), non-DOI content is absent, and bulk crawling without Plus is slow.
Capabilities
- DOI registration for members across content types
- Free public REST API over works, journals, members, funders and more
- Filtering, faceting, sampling and polite pool via mailto
- Content negotiation for BibTeX, RIS and CSL JSON
- Metadata Plus with dedicated servers and monthly snapshots
- Similarity Check and other member services
- Open Funder Registry
Typical workflows
- Resolving DOIs to citation metadata in a reference manager
- Harvesting all works of a journal for a bibliometric study
- Registering DOIs for a university working-paper series
Strengths
- Free API without authentication
- Metadata largely free of copyright restrictions
- Authoritative source for DOI metadata
Limitations
- Coverage limited to member-deposited metadata
- Abstracts and references incomplete
- Heavy use requires Metadata Plus or careful rate handling
Prerequisites
- None for the API; membership to register DOIs
Who it is for
- Publishers and institutional repositories
- Developers of citation and discovery tools
- Scientometricians
Alternatives & comparison
OpenAlex ingests Crossref and adds authors, institutions and topics under CC0; Semantic Scholar adds AI-derived fields under its own licences; ORCID identifies people rather than works; Zenodo registers DOIs through DataCite, the other major agency. Crossref is the canonical source for publisher DOI metadata.
- OpenAlex
Open catalog of the global research system: works, authors, sources, institutions and topics under CC0, served by a REST API, web app and S3 snapshot
Open sourceFree - ORCID
Non-profit registry of persistent researcher identifiers (ORCID iDs) with user-controlled records, Public and Member APIs, OAuth sign-in and an annual CC0 public data file
Open sourceFree - Semantic Scholar
Free AI-assisted literature search from Ai2 with an Academic Graph API, recommendations and downloadable datasets of papers, authors and citations
ProprietaryFree - Zenodo
Free general-purpose research repository operated by CERN that assigns DOIs to datasets, software, papers and other outputs, with a REST API, OAI-PMH, GitHub release archiving and CC0 metadata
Open sourceFree
Sources & verification
Primary sources consulted for this record. Claims are tied to the fields each source supports; the automated link checker re-verifies every URL on a schedule.
- Official documentationREST API - Crossrefchecked Nov 1, 2026
https://www.crossref.org/documentation/retrieve-metadata/rest-api
Supports: capabilities, description, data_formats
Endpoints, mailto polite pool, metadata reuse statement
- Official documentationTips for using the Crossref REST APIchecked Nov 1, 2026
https://www.crossref.org/documentation/retrieve-metadata/rest-api/tips-for-using-the-crossref-rest-api
Supports: limitations
- Official sitechecked Nov 1, 2026
- Pricing pagechecked Nov 1, 2026
- Repositorychecked Nov 1, 2026
- Confidence
- High
- Reviewed
- Nov 1, 2026
- Links
- Verified · Nov 2, 2026
Spotted an error?
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