OpenCitations Metadata API
Operations for retrieving bibliographic metadata
OpenAPI Specification
openapi: 3.0.3
info:
title: OpenCitations Index REST Authors Metadata API
description: 'REST API for accessing the data stored in the OpenCitations Index. Provides operations to retrieve citation data for references to other works appearing in a particular bibliographic entity, or citation data for references in other works to a particular bibliographic entity, given the identifier of a bibliographic entity, or to retrieve citation data about a particular citation identified by means of its Open Citation Identifier (OCI).
All operations return either a JSON document (default) or a CSV document according to the mimetype specified in the Accept header of the request.
API calls are rate-limited to 180 requests/minute per IP address. For large-scale retrieval use the database dumps at download.opencitations.net.
'
version: 2.2.0
contact:
name: OpenCitations
email: contact@opencitations.net
url: https://opencitations.net
license:
name: Creative Commons Attribution 4.0 International
url: https://creativecommons.org/licenses/by/4.0/legalcode
x-api-created: '2025-04-15'
servers:
- url: https://api.opencitations.net/index/v2
description: OpenCitations Index API v2
security:
- accessToken: []
- {}
tags:
- name: Metadata
description: Operations for retrieving bibliographic metadata
paths:
/metadata/{ids}:
get:
summary: Get bibliographic metadata by ID
operationId: getMetadataByIds
description: 'Retrieves the bibliographic metadata for each of the bibliographic entities identified by one or more input IDs.
Each ID is built as follows: ID abbreviation + ":" + ID value. For example, "doi:10.3233/ds-170012" indicates a DOI identifier with value "10.3233/ds-170012".
Supported ID abbreviations: doi, issn, isbn, omid, openalex, pmid, pmcid.
Multiple IDs can be specified separated with double underscore "__". Example: doi:10.1108/jd-12-2013-0166__doi:10.1016/j.websem.2012.08.001
Fields returned: - id: the IDs of the bibliographic entity (space-separated) - title: the title of the bibliographic entity - author: semicolon-separated list of authors - pub_date: date of publication - venue: title of the venue with identifiers - volume: volume number - issue: issue number - page: starting and ending pages - type: type of bibliographic entity - publisher: publisher with identifiers - editor: semicolon-separated list of editors
'
tags:
- Metadata
parameters:
- name: ids
in: path
required: true
description: 'One or more bibliographic entity IDs separated by "__". Supported prefixes: doi, issn, isbn, omid, openalex, pmid, pmcid.
'
schema:
type: string
example: doi:10.1007/978-1-4020-9632-7
- $ref: '#/components/parameters/require'
- $ref: '#/components/parameters/filter'
- $ref: '#/components/parameters/sort'
- $ref: '#/components/parameters/format'
- $ref: '#/components/parameters/json'
responses:
'200':
description: Bibliographic metadata records
content:
application/json:
schema:
type: array
items:
$ref: '#/components/schemas/BibliographicMetadata'
example:
- id: doi:10.1007/978-1-4020-9632-7 isbn:9781402096327 isbn:9789048127108 openalex:W4249829199 omid:br/0612058700
title: Adaptive Environmental Management
author: ''
pub_date: '2009'
page: ''
issue: ''
volume: ''
venue: ''
type: book
publisher: Springer Science And Business Media Llc [crossref:297 omid:ra/0610116006]
editor: Allan, Catherine [orcid:0000-0003-2098-4759 omid:ra/069012996]; Stankey, George H. [omid:ra/061808486861]
text/csv:
schema:
type: string
'404':
description: No metadata found for the given IDs
components:
schemas:
BibliographicMetadata:
type: object
description: Bibliographic metadata for a scholarly work
properties:
id:
type: string
description: 'Space-separated list of identifiers for the bibliographic entity. May include doi, isbn, issn, openalex, omid, pmid, pmcid values.
'
example: doi:10.1007/978-1-4020-9632-7 isbn:9781402096327 omid:br/0612058700
title:
type: string
description: Title of the bibliographic entity
example: Adaptive Environmental Management
author:
type: string
description: 'Semicolon-separated list of authors with their identifiers in brackets. Format: FamilyName, GivenName [orcid:... omid:ra/...]
'
example: Peroni, Silvio [orcid:0000-0003-0530-4305 omid:ra/0610122312]
pub_date:
type: string
description: Publication date (ISO 8601 or partial date)
example: '2009'
issue:
type: string
description: Issue number of the publication
example: '1'
volume:
type: string
description: Volume number of the publication
example: '42'
venue:
type: string
description: Title of the publication venue with identifiers in brackets
example: Scientometrics [issn:0138-9130 omid:br/0612058701]
page:
type: string
description: Starting and ending page numbers
example: 1-25
type:
type: string
description: Type of the bibliographic entity
enum:
- book
- book chapter
- book part
- book section
- book series
- book set
- book track
- component
- dataset
- dissertation
- edited book
- journal
- journal article
- journal issue
- journal volume
- monograph
- other
- peer review
- posted content
- proceedings
- proceedings article
- proceedings series
- reference book
- reference entry
- report
- report series
- standard
- standard series
example: book
publisher:
type: string
description: Publisher name with identifiers in brackets
example: Springer Science And Business Media Llc [crossref:297 omid:ra/0610116006]
editor:
type: string
description: 'Semicolon-separated list of editors with their identifiers in brackets. Format: FamilyName, GivenName [orcid:... omid:ra/...]
'
example: Allan, Catherine [orcid:0000-0003-2098-4759 omid:ra/069012996]
parameters:
filter:
name: filter
in: query
required: false
description: 'Applies conditional filtering. Supports regex or operators (=, <, >). Format: field:operator:value. Example: date:>2015
'
schema:
type: string
example: date:>2015
format:
name: format
in: query
required: false
description: Output format. Accepts "csv" or "json" (default).
schema:
type: string
enum:
- json
- csv
default: json
sort:
name: sort
in: query
required: false
description: 'Orders results by field in ascending or descending order. Format: asc(field) or desc(field).
'
schema:
type: string
example: desc(pub_date)
json:
name: json
in: query
required: false
description: 'Transforms JSON data structure. Supports array splitting or dict conversion.
'
schema:
type: string
require:
name: require
in: query
required: false
description: Removes rows with empty values in the specified field
schema:
type: string
example: doi
securitySchemes:
accessToken:
type: apiKey
in: header
name: authorization
description: 'OpenCitations Access Token obtained from https://opencitations.net/accesstoken. Recommended for application/code usage to ensure stable access.
'
externalDocs:
description: OpenCitations Index API Documentation
url: https://api.opencitations.net/index/v2