Crossref REST API
Provides structured bibliographic metadata and citation relationship data for 150M+ scholarly works registered with a DOI, including journal articles, books, conference papers, and datasets.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
No authentication means no token management risk. All data is public bibliographic metadata. The polite pool email is sent in plain text in the User-Agent header — minor PII consideration.
⚡ Reliability
Best When
An agent needs broad multi-discipline scholarly metadata with reliable DOI resolution and citation linkage across all academic fields.
Avoid When
You need biomedical-specific MeSH indexing, full-text content, or sub-day freshness for citation counts.
Use Cases
- • Resolve a DOI to full citation metadata (title, authors, journal, publication date, abstract) for reference formatting
- • Retrieve forward and backward citation counts for a paper to assess its impact and place it in a research lineage
- • Search the Crossref corpus by keyword, author, or journal to discover relevant literature across all academic disciplines
- • Bulk-download metadata for all publications from a specific funder or institution using filter parameters
- • Validate and enrich a list of raw citation strings by matching them against Crossref's DOI registry
Not For
- • Full-text article retrieval — Crossref only holds metadata and DOI records, not article content
- • Preprints without DOIs — arXiv and bioRxiv content is partially indexed but coverage is incomplete
- • Real-time citation counts — data lags publisher deposit schedules, often by days to weeks
Interface
Authentication
No authentication required. Crossref strongly encourages the 'polite pool' — include a mailto: email address in the User-Agent header or as a query parameter to get better rate limits and priority routing. Registered users get access to the 'plus' service with higher rate limits.
Pricing
Crossref is a non-profit membership organization. The API is free as a public good. Members (publishers) pay to deposit DOIs; end-users pay nothing.
Agent Metadata
Known Gotchas
- ⚠ Cursor-based pagination requires storing the next-cursor token between pages — agents that use offset pagination will get duplicate or missing records
- ⚠ The 'works' endpoint returns up to 1000 results per page; agents must check 'total-results' and paginate even when result count looks small
- ⚠ Without a mailto User-Agent, agents are silently placed in a slower anonymous pool with no warning in the response
- ⚠ Author name disambiguation is not provided — the same person may appear under multiple name variants with no canonical ID
- ⚠ Abstract text is only present when the publisher has explicitly deposited it; many records return no abstract field at all
Alternatives
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Scores are editorial opinions as of 2026-03-06.