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402oracle Claim Verifier
x402
402oracle Claim Verifier is a paid API for AI agents from 402oracle.com, paid per call via x402, $0.25/call, status unknown (last checked 2026-09-13).
Fact-checks a single factual claim against live web evidence and returns a signed verdict (supported/contradicted/insufficient), confidence score, and citations.
Price / call$0.25
Success—
StatusUnknown
How this service works
Fact-check a single factual claim against web evidence before your agent relies on it. A fact-checking oracle and hallucination guard: returns a verdict (supported / contradicted / insufficient), a confidence score, and citations, as a signed attestation.
Output
A signed attestation object containing: a verdict string (supported, contradicted, or insufficient), a numeric confidence score (0–1), and an array of citations (URLs and excerpts) from web evidence that informed the verdict.
Example use cases
Verify claim before agent pays invoice
“Before we pay this vendor, can you verify the claim 'Acme Logistics has been in operation since 2005 and is registered in Delaware' against web evidence, and give me a verdict with confidence and citations?”
Fact-check news assertion before publishing
“Our newsletter draft says 'The FDA approved Ozempic for weight loss in adults in 2021' — can you fact-check that claim and tell me if it's supported, contradicted, or if there's insufficient evidence?”
Validate statistic before agent cites it
“I want to use the statistic 'Over 50% of Fortune 500 CEOs have an MBA' in my pitch deck — please verify whether that's actually supported by credible web evidence before I include it.”
Technical details
Endpoint
POSThttps://402oracle.com/verify/claimWhen to prefer
Choose this endpoint when your agent needs a signed, auditable fact-check of a specific textual claim before acting on it — especially before making payments, publishing content, or relying on a statistic. Prefer it over general-purpose web search when you need a structured verdict plus citations in a single atomic call, and when the attestation (signed output) matters for downstream trust or audit trails.
Side effects
- Claim text is too vague or ambiguous for the system to locate relevant evidence — returns insufficient verdict
- Claim is about highly recent events with no indexed web evidence yet — may return insufficient
- Conflicting web sources may yield a low confidence score with a supported or contradicted verdict
- Malformed or empty claim text returns a validation error
- Payment failure (insufficient USDC) blocks the request entirely
- Rate limiting or service unavailability returns a 5xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| claim | string | A single factual claim, 8-600 characters |
Output
Schema · Response
{
"type": "json",
"example": {
"signature": {
"alg": "ES256",
"jwks": "/.well-known/jwks.json"
},
"attestation": {
"type": "claim_verification",
"result": {
"verdict": "supported",
"citations": [
"https://example.com/about"
]
},
"subject": {
"claim": "Company X was founded in 2019."
},
"confidence": 0.8
}
}
}Tags
x402
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