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Citation Claim Verifier
x402
Citation Claim Verifier is a paid API for AI agents from red-breeze-8b8c.keenanbooker83.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).
Verifies whether a cited source URL actually supports a specific factual claim
Price / call$0.01
Success—
StatusUnknown
How this service works
Verify whether a cited source supports an exact factual claim
Output
A structured assessment indicating whether the provided source URL supports the stated factual claim, including the degree of support (e.g. confirmed, partially supported, not supported, contradicted), relevant excerpts or reasoning from the source, and any caveats or scope mismatches between the claim and what the source actually states.
Example use cases
Academic paper citation audit
“I'm about to submit my research paper and I need to verify this citation: I claimed that 'remote work increases productivity by 13%' and I cited https://nbloom.people.stanford.edu/sites/g/files/sbiybj4746/f/wfh.pdf — can you check if that source actually backs up that exact claim?”
Journalism fact-check before publication
“Before I publish this article, can you verify whether this source actually supports my claim? I wrote that 'over 50% of Americans now live paycheck to paycheck' and linked to https://www.bankrate.com/banking/savings/financial-security-march-2023/ — does that URL actually say that?”
Debate argument source validation
“I'm preparing a debate and I want to make sure this source is solid — my claim is 'electric vehicles produce fewer lifetime emissions than gas cars even accounting for battery manufacturing' and I'm citing https://theicct.org/publication/a-global-comparison-of-the-life-cycle-greenhouse-gas-emissions-of-combustion-engine-and-electric-passenger-cars/. Does that source genuinely support what I'm claiming?”
Technical details
Endpoint
POSThttps://red-breeze-8b8c.keenanbooker83.workers.dev/verify-citationWhen to prefer
Use this endpoint when you need to verify that a specific citation actually supports a precise factual claim — ideal for pre-publication fact-checking, academic citation audits, or validating arguments before use. Prefer this over a general fact-checker when you already have both the claim and the source URL, and need a binary or graded judgment about whether the source justifies the claim. Choose this over the statistical-claim evaluator when the claim is a general fact rather than a statistical assertion.
Side effects
- Source URL is paywalled or access-restricted — cannot retrieve content to verify
- URL returns 404 or is otherwise unavailable
- Claim text is too vague or ambiguous to test against a source
- Source is a non-text format (e.g. video, audio) that cannot be parsed
- Rate limiting or network errors prevent source retrieval
- Claim exceeds 4000 character limit
- Source URL exceeds 2048 character limit
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| claim | string | The exact factual claim to test against the cited source. |
| sourceUrl | string | Public URL of the source that allegedly supports the claim. |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"result": {
"agent": {
"id": "citation-verification",
"version": "2.0.0"
},
"claim": "The United States declared war on Japan on December 8, 1941.",
"verification": {
"verdict": "supported",
"confidence": 0.98
}
}
}
}Tags
x402
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