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FactStamp Citation & Entity Verification
x402
FactStamp Citation & Entity Verification is a paid API for AI agents from factstamp.agentrails.workers.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-02).
Verifies figures, entities, citations, and dependencies against dated primary sources, returning a verified/unverified verdict with source metadata
Price / call$0.02
Success—
StatusUnknown
How this service works
Figure, entity, citation and dependency verification for other agents. Cited to dated primary sources. Unknown is valid.
Output
A JSON object containing the query kind (e.g. doi), the queried identifier, a record with structured bibliographic metadata (title, authors, year, journal, publisher, retraction status), a list of sources consulted with HTTP status, and an overall verdict of 'verified' or similar.
Example use cases
Fact-checking AI-generated research summaries
“I have a research summary an AI wrote that cites DOI 10.1126/science.abc1234 — can you verify that citation actually exists, isn't retracted, and give me the real title and authors?”
Pre-publication reference audit
“Before I submit my report, can you check if the citation 10.1016/j.cell.2021.01.001 is valid, who published it, and whether it's been retracted?”
Agent pipeline citation grounding
“My agent just cited a Nature paper with DOI 10.1038/s41586-020-2649-2 as a source — verify it's a legitimate primary source and tell me the year and journal it appeared in.”
Technical details
Endpoint
POSThttps://factstamp.agentrails.workers.dev/citation?utm_source=zero.xyzWhen to prefer
Use FactStamp when you need authoritative, source-cited verification of academic DOIs, entities, or factual claims with a clear verdicts and retraction checks — especially in agentic pipelines where hallucinated citations need to be caught before output is delivered. Prefer it over general web search when you need structured bibliographic metadata and primary-source grounding rather than a scraped or synthesized answer.
Side effects
- DOI or identifier not found in any source — returns unverified verdict
- Source APIs (e.g. Crossref) return non-200 status — partial or failed lookup
- Malformed or unsupported citation format — may return error or unknown verdict
- Retracted paper — returned as verified but with retraction metadata populated
- Payment not fulfilled — x402 payment required response before processing
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| outputrequired | object |
Output
Schema · Response
{
"type": "json",
"example": {
"kind": "doi",
"query": "10.1038/nature12373",
"record": {
"doi": "10.1038/nature12373",
"type": "journal-article",
"year": 2013,
"title": "Nanometre-scale thermometry in a living cell",
"authors": [
"G. Kucsko",
"P. C. Maurer",
"N. Y. Yao"
],
"container": "Nature",
"publisher": "Springer Science and Business Media LLC",
"retraction": null
},
"sources": [
{
"name": "Crossref",
"http_status": 200
}
],
"verdict": "verified"
}
}Tags
x402
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