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

Example Payloads

Author Works

4 fields

EXAMPLE

Citation By Oci

4 fields

EXAMPLE

Citation Count

4 fields

EXAMPLE

Incoming Citations

5 fields

EXAMPLE

Metadata Lookup

4 fields

EXAMPLE

Resources

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: contact@opencitations.net
    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: contact@opencitations.net
    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: contact@opencitations.net
    X-website: https://opencitations.net
maintainers:
- FN: OpenCitations
  email: contact@opencitations.net
  X-website: https://opencitations.net
common:
- type: DomainSecurity
  url: security/opencitations-domain-security.yml
- type: Authentication
  url: authentication/opencitations-authentication.yml