--- name: crossref-api-90ee7be8c98c description: "Resolve DOIs and retrieve publication metadata from CrossRef registry" metadata: openclaw: emoji: "🔍" category: "literature" subcategory: "metadata" keywords: ["DOI resolution", "digital object identifier", "CrossRef", "citation statistics", "citation tracking"] source: "https://api.crossref.org" --- # 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**: | Param | Type | Required | Description | |-------|------|----------|-------------| | query | string | No | Free-text query across all metadata fields | | query.title | string | No | Search specifically in titles | | query.author | string | No | Search specifically by author name | | filter | string | No | Structured filters (e.g., from-pub-date:2024, type:journal-article) | | sort | string | No | Sort field: relevance, published, is-referenced-by-count | | order | string | No | asc or desc | | rows | integer | No | Results per page (default: 20, max: 1000) | | offset | integer | No | Pagination offset | | mailto | string | No | Email for polite pool | - **Example**: ```bash 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**: | Param | Type | Required | Description | |-------|------|----------|-------------| | doi | string | Yes | The DOI to resolve (URL path parameter) | | mailto | string | No | Email for polite pool | - **Example**: ```bash 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**: | Param | Type | Required | Description | |-------|------|----------|-------------| | query | string | No | Publisher name search | | rows | integer | No | Results per page | - **Example**: ```bash 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**: | Param | Type | Required | Description | |-------|------|----------|-------------| | query | string | No | Journal title search | | rows | integer | No | Results per page | - **Example**: ```bash 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: ```bash # 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: ```bash 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: ```bash curl "https://api.crossref.org/works/10.1038/s41586-021-03819-2?mailto=user@example.com" | jq '.message["is-referenced-by-count"]' ``` ## References - Official documentation: https://api.crossref.org - API documentation: https://api.crossref.org/swagger-ui/index.html - CrossRef metadata best practices: https://www.crossref.org/documentation/ --- Source attribution: wentorai Original project: https://github.com/wentorai/research-plugins/blob/bf44b3cd617fa94c8a1b254c5d1987142ca3d631/skills/literature/metadata/crossref-api/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice MIT License Copyright (c) 2026 Wentor AI Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Mega AI Hub resource metadata Creator / publisher: wentorai Original project: https://github.com/wentorai/research-plugins/blob/bf44b3cd617fa94c8a1b254c5d1987142ca3d631/skills/literature/metadata/crossref-api/SKILL.md Attribution basis: Source repository record Fields of work: Data & Analytics, Education & Research, Marketing Roles: Data Analyst, Marketing Analyst, Researcher Specialties: API Tools: Crossref Api Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 253f21ecc5aca2ea1bd3589ade7a587b123ba762e7af2f1178ccc7e90289a9a3