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crossref-api

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Resolve DOIs and retrieve publication metadata from CrossRef registry

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Source SKILL.md: https://github.com/brycewang-stanford/Auto-Empirical-Research-Skills/blob/HEAD/skills/43-wentorai-research-plugins/skills/literature/metadata/crossref-api/SKILL.md

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CrossRef API Guide

Overview

CrossRef is the official DOI registration agency for scholarly publishing, maintaining metadata for over 150 million content items including journal articles, books, conference proceedings, preprints, and datasets. The CrossRef REST API provides free, open access to this metadata, making it the authoritative source for resolving Digital Object Identifiers (DOIs) and retrieving standardized publication records.

Publishers deposit metadata with CrossRef when they register DOIs for their content. This makes the CrossRef API a reliable source for bibliographic information, citation counts, licensing data, funder acknowledgments, and links to full-text resources. The API is used extensively in reference management, citation analysis, and research information systems.

The API is free and requires no authentication. Users who include a mailto parameter in their requests are placed in the "polite pool" which provides faster and more reliable service.

Authentication

No authentication required. For best performance, include your email to access the polite pool:

https://api.crossref.org/works?mailto=your@email.com

Users in the polite pool receive prioritized responses and are not subject to the same rate limiting as anonymous users. CrossRef Plus subscribers get additional benefits including guaranteed uptime and higher throughput.

Core Endpoints

Works: Query Publication Metadata

  • URL: GET https://api.crossref.org/works
  • Parameters:
    ParamTypeRequiredDescription
    querystringNoFree-text query across all metadata fields
    query.titlestringNoSearch specifically in titles
    query.authorstringNoSearch specifically by author name
    filterstringNoStructured filters (e.g., from-pub-date:2024, type:journal-article)
    sortstringNoSort field: relevance, published, is-referenced-by-count
    orderstringNoasc or desc
    rowsintegerNoResults per page (default: 20, max: 1000)
    offsetintegerNoPagination offset
    mailtostringNoEmail for polite pool
  • Example: 
    curl "https://api.crossref.org/works?query.title=attention+is+all+you+need&rows=5&mailto=user@example.com"
  • Response: JSON with message.items array containing DOI, title, author, published, is-referenced-by-count, reference, license, and link fields.

Works by DOI: Direct DOI Resolution

  • URL: GET https://api.crossref.org/works/{doi}
  • Parameters:
    ParamTypeRequiredDescription
    doistringYesThe DOI to resolve (URL path parameter)
    mailtostringNoEmail for polite pool
  • Example: 
    curl "https://api.crossref.org/works/10.1038/s41586-021-03819-2?mailto=user@example.com"
  • Response: JSON with complete metadata record for the DOI, including all registered bibliographic information.

Members: Publisher Information

  • URL: GET https://api.crossref.org/members
  • Parameters:
    ParamTypeRequiredDescription
    querystringNoPublisher name search
    rowsintegerNoResults per page
  • Example: 
    curl "https://api.crossref.org/members?query=springer&rows=5&mailto=user@example.com"
  • Response: JSON with publisher metadata including member ID, name, prefix list, and coverage statistics.

Journals: Journal Metadata

  • URL: GET https://api.crossref.org/journals
  • Parameters:
    ParamTypeRequiredDescription
    querystringNoJournal title search
    rowsintegerNoResults per page
  • Example: 
    curl "https://api.crossref.org/journals?query=nature+machine+intelligence&rows=5&mailto=user@example.com"
  • Response: JSON with journal information including ISSN, title, publisher, subject, and coverage counts.

Rate Limits

Anonymous users: no hard limit but throttled under load. Polite pool users (with mailto): prioritized access with no published rate cap. CrossRef Plus subscribers: guaranteed uptime with SLA. The API returns HTTP 429 when overloaded. Use exponential backoff and always include mailto for production applications. For bulk metadata retrieval, CrossRef provides database snapshots and the Public Data File.

Common Patterns

Validate and Enrich a Reference List

Resolve a list of DOIs to get standardized metadata:

# Single DOI resolution with full metadata
curl "https://api.crossref.org/works/10.1145/3292500.3330672?mailto=user@example.com"

Find Recent Highly-Cited Papers in a Field

Filter by publication date and sort by citation count:

curl "https://api.crossref.org/works?filter=from-pub-date:2023,type:journal-article&query=machine+learning&sort=is-referenced-by-count&order=desc&rows=20&mailto=user@example.com"

Track Citation Growth

Monitor citation counts for a specific DOI over time:

curl "https://api.crossref.org/works/10.1038/s41586-021-03819-2?mailto=user@example.com" | jq '.message["is-referenced-by-count"]'

References