OpenCitations

OpenCitations is an open science research infrastructure providing free access to scholarly bibliographic and citation data. It offers REST APIs for querying citation networks, DOI-based citation lookups, reference data, and bibliographic metadata from millions of research articles. All data is published under CC0 Public Domain Waiver for unrestricted reuse.

3 APIs 0 Features

CitationsScholarlyResearchOpen ScienceBibliometricsDOIAcademic

APIs

OpenCitations Index API

REST API for accessing citation entities in the OpenCitations dataset. Provides citation counts, incoming/outgoing reference lookups, and citation metadata by DOI, PMID, or OMID...

OpenCitations Meta API

REST API for retrieving bibliographic metadata associated with documents involved in citations. Supports lookup by DOI, ISSN, ISBN, OMID, OpenAlex ID, PMID, and PMCID. Also prov...

OpenCitations SPARQL Endpoint

SPARQL endpoints for structured queries against the OpenCitations Meta and Index datasets. Provides access to the full Linked Open Data graph for both bibliographic metadata and...

Semantic Vocabularies

Opencitations Context

24 classes · 13 properties

JSON-LD

Sources

name: OpenCitations
description: OpenCitations is an open science research infrastructure providing free
  access to scholarly bibliographic and citation data. It offers REST APIs for querying
  citation networks, DOI-based citation lookups, reference data, and bibliographic
  metadata from millions of research articles. All data is published under CC0 Public
  Domain Waiver for unrestricted reuse.
image: https://opencitations.net/static/favicon.ico
url: https://opencitations.net
created: '2024-01-01'
modified: '2026-06-13'
specificationVersion: '0.19'
tags:
  - Citations
  - Scholarly
  - Research
  - Open Science
  - Bibliometrics
  - DOI
  - Academic
apis:
  - name: OpenCitations Index API
    description: REST API for accessing citation entities in the OpenCitations dataset.
      Provides citation counts, incoming/outgoing reference lookups, and citation
      metadata by DOI, PMID, or OMID. Aggregates data across all OpenCitations indexes
      including COCI (Crossref open DOI-to-DOI citations).
    image: https://opencitations.net/static/favicon.ico
    humanURL: https://api.opencitations.net/index/v2
    baseURL: https://api.opencitations.net/index/v2
    tags:
      - Citations
      - References
      - DOI
      - Scholarly
    properties:
      - type: Documentation
        url: https://api.opencitations.net/index/v2
      - type: OpenAPI
        url: https://kinlane.github.io/all/opencitations/openapi/index-api.yml
      - type: RateLimits
        url: https://kinlane.github.io/all/opencitations/rate-limits/index-api.html
    contact:
      - FN: OpenCitations
        email: [email protected]
        X-website: https://opencitations.net
    version: 2.2.0
  - name: OpenCitations Meta API
    description: REST API for retrieving bibliographic metadata associated with documents
      involved in citations. Supports lookup by DOI, ISSN, ISBN, OMID, OpenAlex ID,
      PMID, and PMCID. Also provides author and editor-based queries using ORCID or
      OMID identifiers.
    image: https://opencitations.net/static/favicon.ico
    humanURL: https://api.opencitations.net/meta/v1
    baseURL: https://api.opencitations.net/meta/v1
    tags:
      - Bibliographic Metadata
      - DOI
      - ORCID
      - Scholarly
    properties:
      - type: Documentation
        url: https://api.opencitations.net/meta/v1
      - type: OpenAPI
        url: https://kinlane.github.io/all/opencitations/openapi/meta-api.yml
      - type: RateLimits
        url: https://kinlane.github.io/all/opencitations/rate-limits/meta-api.html
    contact:
      - FN: OpenCitations
        email: [email protected]
        X-website: https://opencitations.net
    version: 1.1.1
  - name: OpenCitations SPARQL Endpoint
    description: SPARQL endpoints for structured queries against the OpenCitations
      Meta and Index datasets. Provides access to the full Linked Open Data graph
      for both bibliographic metadata and citation entity data using the SPARQL query
      language.
    image: https://opencitations.net/static/favicon.ico
    humanURL: https://sparql.opencitations.net
    baseURL: https://sparql.opencitations.net
    tags:
      - SPARQL
      - Linked Open Data
      - RDF
      - Scholarly
    properties:
      - type: Documentation
        url: https://sparql.opencitations.net
    contact:
      - FN: OpenCitations
        email: [email protected]
        X-website: https://opencitations.net
maintainers:
  - FN: OpenCitations
    email: [email protected]
    X-website: https://opencitations.net