Every claim, verified.

citation.is is an open registry of verified scientific claims. Each claim is extracted from peer-reviewed literature, assigned a structured verdict — Supported, Refuted, Inconclusive, or Needs Context — and cross-referenced against authoritative databases including UniProt, PubChem, NCBI Taxonomy, and PubMed.

The registry currently contains over 3,900 verified claims across domains including structural biology, salmon aquaculture, and biotech. All data is published under CC BY 4.0 and is freely accessible via REST API, MCP (Model Context Protocol), OAI-PMH, and bulk download.

Research Verticals

Domain-specific claim verification engines cover structural biology, salmon aquaculture biotech, and more. Each vertical maps claims to entities in the knowledge graph and cross-references them against the relevant authoritative databases.

Open API and Agent Access

All claims are accessible via a public REST API at /api/external/public/claims. An MCP (Model Context Protocol) server is available at /mcp for direct agent integration. Full API documentation is available at /developers. The OpenAPI specification is at /openapi.json.

Open Data

All data is published under the Creative Commons CC BY 4.0 license. Bulk download is available at /api/public/claims.json. OAI-PMH harvesting is available at /oai in both Dublin Core and DataCite 4.x formats, making the registry eligible for indexing by BASE, OpenAIRE, and Semantic Scholar.

How Claim Verification Works

Each claim in the registry passes through a multi-stage verification pipeline. First, the claim is extracted from the source document and normalised into a structured assertion with a subject, predicate, and object. The subject and object are then resolved against knowledge graph entities — proteins are matched to UniProt accessions, chemical compounds to PubChem CIDs, organisms to NCBI Taxonomy IDs, and publications to PubMed PMIDs.

The resolved claim is then evaluated against the evidence in the source document and any corroborating or contradicting literature. The final verdict is one of four values: Supported (the evidence directly confirms the claim), Refuted (the evidence contradicts it), Inconclusive (the evidence is mixed or insufficient), or Needs Context (the claim is conditionally true and requires additional framing to be interpreted correctly).

All verified claims are assigned a persistent identifier and are immediately available via the public API, the MCP server, and the OAI-PMH endpoint. The knowledge graph is updated continuously as new documents are processed.

Use Cases

citation.is is designed for researchers who need to verify claims in scientific literature, AI systems that require grounded, citable facts, and publishers who want to add structured verification metadata to their content. The registry is also used by fact-checking tools, systematic review pipelines, and knowledge graph construction workflows.

Agents and LLMs can query the registry directly via the MCP server at /mcp, which exposes two tools: search_claims (full-text search with filters) and verify_claim (submit a claim text and receive a structured verdict with supporting evidence). No authentication is required. All endpoints are rate-limit free for reasonable use.