OpenCitations

by

The open infrastructure for citation data.

At a Glance

PublisherOpenCitations (a nonprofit scholarly-infrastructure organization)
Coverageopen citation data — the OpenCitations Index (including the former COCI) holds hundreds of millions of DOI-to-DOI citations, released under CC0
Accessfree; open API and data dumps
Regionalglobal.

Our Take

OpenCitations is the open answer to a quietly important problem — citation data has historically been locked inside paywalled indexes. By publishing hundreds of millions of citations as open CC0 data, it underpins independent bibliometrics and feeds tools like OpenAlex and Dimensions. It’s infrastructure, not a search interface, so it’s for builders and analysts more than casual searchers. Use it as a free, reusable citation-data source for bibliometric work and to support open metrics; pair with OpenAlex for the surrounding metadata.

Power Tips

  • Pull OpenCitations’ CC0 citation data via API or dump to run citation analyses without a paywalled index (the open-tools-at-scale principle, Issue 1)
  • combine it with OpenAlex metadata to build a full, open citation-network analysis (Issue 2).

Alternatives & Complements

OpenAlex · Dimensions · Web of Science · Scite.