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.

OpenCitations publishes 5 APIs on the APIs.io network, including Authors API, Citations API, Editors API, and 2 more. Tagged areas include Citations, Scholarly, Research, Open Science, and Bibliometrics.

The OpenCitations catalog on APIs.io includes 1 JSON-LD context.

OpenCitations’ developer surface includes authentication and 2 more developer resources.

🌐 Visit website 📡 Source on GitHub

28.4/100 thin ▬ flat Agent 31/100 agent aware Full breakdown ↓
scored 2026-08-05 · rubric v0.9.1

AccessSelf serve

6 APIs

CitationsScholarlyResearchOpen ScienceBibliometricsDOIAcademic

Kin Score

Kin Score How this is scored →
scored 2026-08-05 · rubric v0.9.1

Composite quality — 28.4/100 · thin

Contract Quality 18.1 / 25

Developer Ergonomics 2.2 / 20

Commercial Clarity 0.0 / 20

Operational Transparency 0.0 / 13

Governance 0.0 / 12

Discoverability 8.2 / 10

Agent readiness — 31/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/opencitations: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 6

Individual APIs this provider publishes, each with its own machine-readable definition.

Examples 5

Example request and response payloads for these APIs.

AGENTIC

Resources

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Source (apis.yml)

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.
accessModel:
  pricing: unknown
  onboarding: self-serve
  trial: false
  try_now: false
  public: false
  label: Self-serve signup
  confidence: medium
  source:
  - authentication
  generated: '2026-07-22'
  method: derived
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 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
- aid: opencitations:opencitations-authors-api
  name: OpenCitations Authors API
  description: Operations for retrieving works by author
  humanURL: https://api.opencitations.net/index/v2
  baseURL: https://api.opencitations.net/index/v2
  tags:
  - Authors
  properties:
  - type: OpenAPI
    url: openapi/opencitations-authors-api-openapi.yml
  - type: Documentation
    url: https://api.opencitations.net/index/v2
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/index-api.html
  - type: Documentation
    url: https://api.opencitations.net/meta/v1
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/meta-api.html
- aid: opencitations:opencitations-citations-api
  name: OpenCitations Citations API
  description: Operations for retrieving citation metadata and counts
  humanURL: https://api.opencitations.net/index/v2
  baseURL: https://api.opencitations.net/index/v2
  tags:
  - Citations
  properties:
  - type: OpenAPI
    url: openapi/opencitations-citations-api-openapi.yml
  - type: Documentation
    url: https://api.opencitations.net/index/v2
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/index-api.html
  - type: Documentation
    url: https://api.opencitations.net/meta/v1
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/meta-api.html
- aid: opencitations:opencitations-editors-api
  name: OpenCitations Editors API
  description: Operations for retrieving works by editor
  humanURL: https://api.opencitations.net/index/v2
  baseURL: https://api.opencitations.net/index/v2
  tags:
  - Editors
  properties:
  - type: OpenAPI
    url: openapi/opencitations-editors-api-openapi.yml
  - type: Documentation
    url: https://api.opencitations.net/index/v2
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/index-api.html
  - type: Documentation
    url: https://api.opencitations.net/meta/v1
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/meta-api.html
- aid: opencitations:opencitations-metadata-api
  name: OpenCitations Metadata API
  description: Operations for retrieving bibliographic metadata
  humanURL: https://api.opencitations.net/index/v2
  baseURL: https://api.opencitations.net/index/v2
  tags:
  - Metadata
  properties:
  - type: OpenAPI
    url: openapi/opencitations-metadata-api-openapi.yml
  - type: Documentation
    url: https://api.opencitations.net/index/v2
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/index-api.html
  - type: Documentation
    url: https://api.opencitations.net/meta/v1
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/meta-api.html
- aid: opencitations:opencitations-references-api
  name: OpenCitations References API
  description: Operations for retrieving outgoing reference data
  humanURL: https://api.opencitations.net/index/v2
  baseURL: https://api.opencitations.net/index/v2
  tags:
  - References
  properties:
  - type: OpenAPI
    url: openapi/opencitations-references-api-openapi.yml
  - type: Documentation
    url: https://api.opencitations.net/index/v2
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/index-api.html
  - type: Documentation
    url: https://api.opencitations.net/meta/v1
  - type: RateLimits
    url: https://kinlane.github.io/all/opencitations/rate-limits/meta-api.html
maintainers:
- FN: OpenCitations
  email: contact@opencitations.net
  X-website: https://opencitations.net
common:
- type: AgenticAccess
  url: agentic-access/opencitations-agentic-access.yml
- type: DomainSecurity
  url: security/opencitations-domain-security.yml
- type: Authentication
  url: authentication/opencitations-authentication.yml

OpenCitations

Kin Score

APIs 6

OpenCitations SPARQL Endpoint

OpenCitations Authors API

OpenCitations Citations API

OpenCitations Editors API

OpenCitations Metadata API

OpenCitations References API

Semantic Vocabularies 1

Opencitations Context

Examples 5

Author Works

Citation By Oci

Citation Count

Incoming Citations

Metadata Lookup

Security Posture 2

Opencitations Authentication

Opencitations Domain Security

Agentic Access 1

Opencitations Agentic Access

Resources

Agent Surfaces 1

Access & Security 2

Source (apis.yml)