# aiworker Claim Checker

> aiworker Claim Checker is a paid API for AI agents from aiworker.duckdns.org, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Extracts factual claims from text or a URL and verdicts each one as supported, contradicted, unsupported, or unverifiable, with quoted evidence from Wikipedia and supplied sources.

## Facts

- Endpoint: POST https://aiworker.duckdns.org/v1/check/claims
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/aiworker-claim-checker-cbedde4f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_A8r1hH-o4u8ZJkCYCoCVM

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability aiworker-claim-checker-cbedde4f -d '<json body>'
```

Example prompt: Can you fact-check this paragraph for me: 'The Eiffel Tower is 330 meters tall and was built in 1889 for the World's Fair' — extract up to 3 claims and verdict each one against Wikipedia, with quoted evidence?

## When to prefer this

Choose this endpoint when you need structured, evidence-backed verdicts on specific factual claims with verbatim quotes from Wikipedia or supplied sources. It is ideal for fact-checking user-submitted text, validating article content, or auditing documents for false or unsupported assertions. Prefer it over generic LLM fact-checking because it provides citable, verbatim evidence and explicit verdict categories rather than prose opinion.

## Known failure modes

- If neither 'text' nor 'url' is provided, or both are provided simultaneously, the request is rejected
- If the URL is not publicly accessible or returns a non-200 status, fetching fails
- If text exceeds 8000 characters, the request is rejected
- If max_claims exceeds 8 or is less than 1, validation error is returned
- Wikipedia or supplied source URLs may be temporarily unreachable, resulting in unverifiable verdicts
- Some claims may be too vague or subjective to verdict, returning 'unverifiable'
- Payment of $0.05 USDC via x402 protocol is required; missing or invalid payment results in 402 response

## How this service works

Deterministic-first data for agents, paid per call in USDC over x402 v2: DeFi yields, Base token and wallet cards, Polymarket odds and backtests, news, fact checks, cited briefs. 20 routes, $0.005-$1

## Output

A JSON object containing the list of extracted factual claims, each with a unique ID, the claim statement, a verdict label (supported/contradicted/unsupported/unverifiable), a confidence score, a rationale, and verbatim evidence quotes with source URLs. Also includes metadata about which sources were consulted (Wikipedia and any supplied URLs), the model used, and input summary.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "a public https url whose page is fetched and checked instead of text"
  },
  "text": {
   "type": "string",
   "maxLength": 8000,
   "description": "buyer text to check, at most 8 000 characters; exactly one of text or url is required"
  },
  "sources": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 5,
   "description": "up to 5 https urls the model may cite as evidence, in addition to Wikipedia"
  },
  "max_claims": {
   "type": "integer",
   "maximum": 8,
   "minimum": 1,
   "description": "maximum claims to extract and verdict; default 5"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "input": {
   "kind": "text",
   "chars": 62
  },
  "model": "mimo-v2.5",
  "route": "POST /v1/check/claims",
  "claims": [
   {
    "id": "c1",
    "verdict": "supported",
    "evidence": [
     {
      "url": "https://en.wikipedia.org/wiki/Eiffel_Tower",
      "quote": "…330 m (1,083 ft) tall…"
     }
    ],
    "rationale": "Wikipedia's summary states the same height.",
    "statement": "The Eiffel Tower is 330 meters tall.",
    "confidence": 0.8
   }
  ],
  "version": 1,
  "sources_consulted": [
   {
    "url": "https://en.wikipedia.org/wiki/Eiffel_Tower",
    "kind": "wikipedia",
    "title": "Eiffel Tower",
    "fetched": true
   }
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aiworker-claim-checker-cbedde4f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from aiworker.duckdns.org](https://www.zero.xyz/host/aiworker.duckdns.org/llms.txt)