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Claim Evaluator
x402
Claim Evaluator is a paid API for AI agents from claim-evaluator.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).
Scores the likelihood (0–100) that a factual claim is true, returning reasoning and cited web sources
Price / call$0.05
Success—
StatusUnknown
How this service works
Evaluate the likelihood of an LLM statement being true — with sources. Score 0–100, reasoning, and cited web sources. Pay per call via MPP.
Output
A JSON object containing: a `likelihood` score (0–100 integer, where 0 = definitely false and 100 = definitely true), a `reasoning` string (2–3 sentence assessment of the evidence), and a `sources` array of 3–5 web sources each with a name, URL, stance (confirm/deny/unclear), and a brief summary of what that source says about the claim.
Example use cases
Fact-checking AI-generated content
“I just got this answer from an AI: 'Aspirin was first synthesized in 1897 by Felix Hoffmann at Bayer.' Can you verify that claim, give it a likelihood score, and show me the sources that back it up or contradict it?”
Verifying a news article statistic
“Someone shared an article claiming 'Global electric vehicle sales surpassed 10 million units in 2022.' Can you fact-check that and tell me how likely it is to be true, with sources?”
Checking a debated historical claim
“My friend insists that 'Napoleon Bonaparte was unusually short for his time.' Can you score how likely that's actually true and pull some cited sources for me?”
Technical details
Endpoint
POSThttps://claim-evaluator.com/v1/evaluateWhen to prefer
Choose this endpoint when you need a structured, sourced truth score for a specific factual claim — especially to validate LLM-generated statements, fact-check user assertions, or add citation-backed credibility scoring to a pipeline. It is purpose-built for single-claim evaluation with a numerical score and cited stances, making it ideal over general web search when you need structured verification output rather than raw search results.
Side effects
- Claim is too vague or opinion-based — endpoint performs best on concrete, checkable statements
- No reliable sources found for very obscure or niche claims — may return sources with 'unclear' stance
- LLM hallucination in reasoning if claim touches highly specialized domains
- Rate limiting or payment failure if USDC balance is insufficient for the $0.05 per-call fee
- Empty or malformed `claim` field returns a validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| claimrequired | string | Single factual claim to score. Prefer concrete, checkable statements over opinions or forecasts. |
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| sourcesrequired | array | |
| reasoningrequired | string | 2–3 sentence assessment |
| likelihoodrequired | number | 0 = definitely false, 100 = definitely true |
Tags
x402
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