OpenCitations Meta

The OpenCitations Meta database stores and delivers bibliographic metadata for all publications involved in the OpenCitations Index.

For each publication, the metadata exposed by OpenCitations Meta includes the publication's title, type, venue (e.g. journal name), volume number, issue number, page numbers, publication date, and identifiers such as Digital Object Identifiers (DOIs) and PubMed Identifiers (PMIDs). In addition, OpenCitations Meta includes details of the main actors involved in the publication of the document, i.e., the names of the authors, editors, and publishers, each with its own additional metadata and identifier (e.g. ORCID).

Currently, OpenCitations Meta contains:

OpenCitations Meta was first released on 20 December 2022.

Entity URLs

Each entity is identified by a URI structured as follows:[[OMID]]

The OpenCitations Meta Identifier

Every entity in OpenCitations Meta is assigned persistent internal identifier called OpenCitations Meta Identifier (OMID). The OMID has structure [[entity_type_abbreviation]]/[[supplier_prefix]][[sequential_number]]. For example, the first journal article ever processed has OMID br/0601 (the full URI is, where br is the abbreviation of bibliographic resource, and 060 corresponds to the supplier prefix, helpful in recognising at a glance the index it belongs to (i.e., OpenCitations Meta). Finally, 1 indicates that this is the index's first bibliographic resource ever minted.

The entities subject to deduplication and associated with an OMID are identifiers (abbr. id), agent roles (i.e., authors, editors, publishers, abbr. ar), responsible agents (i.e., people and organisations, abbr. ra), resource embodiments (i.e., pages, abbr. re), venues, volumes, and issues (which are all bibliographic resources, abbr. br).

On the contrary, titles, types, and dates are treated as literal values, not entities.

Access to OpenCitations Meta data

All the data in OpenCitations Meta: