OpenCitations
OpenCitations is an open scholarly citation website and research infrastructure for bibliographic metadata, citation indexes, linked open data, downloads, and APIs.
What OpenCitations is
OpenCitations is a website at opencitations.net and an open research infrastructure for scholarly bibliographic and citation data. It provides human-readable pages, dataset descriptions, downloadable data, and APIs for people who need citation links and metadata without relying only on proprietary citation indexes.
Why citations are data
A citation is more than a line in a reference list. It connects one scholarly work to another, creating a network that can be used for discovery, credit, research evaluation, literature mapping, and history of science. OpenCitations treats those links as reusable data that can be queried, downloaded, and combined with other open scholarly metadata.
COCI and other indexes
One of OpenCitations' best-known resources is COCI, the OpenCitations Index of Crossref open DOI-to-DOI citations. OpenCitations has also developed other indexes and datasets around open citation and bibliographic metadata. Each dataset has its own source coverage, identifiers, update cycle, and limits, so users should check the documentation rather than assuming complete coverage of all scholarship.
Open licenses and reuse
OpenCitations emphasizes reuse. Its data is published under a CC0 public domain dedication, while its website text and software use their own stated licenses. That distinction matters: data, text, and code may have different permissions even when they belong to the same project.
Linked open data
OpenCitations uses Semantic Web and linked-data approaches so citations and bibliographic entities can be represented in machine-readable ways. This helps software connect works, citations, identifiers, publishers, venues, and sources across systems. The tradeoff is that users need to understand identifiers, provenance, and data formats to avoid overreading a graph as a complete map.
APIs and downloads
The OpenCitations API and download services let developers query citation entities, bibliographic metadata, and dataset slices for research tools, library systems, dashboards, and reproducible analyses. APIs are convenient for targeted lookup, while bulk downloads are better for large-scale processing where rate limits, versioning, and reproducibility matter.
Strengths and limits
OpenCitations is strongest when a project needs open citation metadata that can be inspected, reused, and combined with other open datasets. Its limits are the limits of available open sources, identifier quality, dataset scope, and update pipelines. It is an important open infrastructure, not a complete record of every citation ever made.
Why it matters
OpenCitations matters because citation data shapes how research is found, counted, connected, and evaluated. Making that data open supports reproducible bibliometrics, transparent discovery tools, independent research assessment, and alternatives to closed citation databases. It also makes the remaining gaps easier to see.
WHOIS domain data
Data pulled: June 1, 2026View current WHOIS record
- Domain
- opencitations.net
- IP address
- 137.204.119.90
- Registrar
- Gandi SAS
- WHOIS server
- whois.gandi.net
- Referral URL
- http://www.gandi.net
- Created
- March 17, 2010
- Updated
- January 30, 2026
- Expires
- March 17, 2028
- Nameservers
- ns-200-b.gandi.net (213.167.230.201); ns-39-a.gandi.net (173.246.100.40); ns-69-c.gandi.net (217.70.187.70)
- Domain status
- clientTransferProhibited
- DNSSEC
- unsigned