# Fact-Checker API (klymax402)

> Fact-Checker API (klymax402) is a paid API for AI agents from fact-checker.api.klymax402.com, paid per call via x402, $0.012/call, status unknown (last checked 2026-09-13).

Verifies a factual claim by searching for evidence online and returning sourced results

## Facts

- Endpoint: GET https://fact-checker.api.klymax402.com/api/check
- Price: $0.012/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fact-checker-api-klymax402-a34c4452
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_O8BrEZfVcY-t1knCvdSeY

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 fact-checker-api-klymax402-a34c4452
```

Example prompt: Can you fact-check this claim for me: 'The Eiffel Tower is 330 meters tall' — and pull up to 8 sources so I can see the evidence?

## When to prefer this

Use this endpoint when you need to verify a specific factual claim against real online evidence and want sourced results. Prefer this over general web search when you want a structured fact-check response rather than raw search results, and when the query is a concrete verifiable assertion rather than an open-ended question.

## Known failure modes

- Claim string is empty or missing — likely returns 400 or validation error
- max_sources exceeds 10 — may be capped or return an error
- Claim is too ambiguous or unverifiable — may return low-confidence or no sources
- Network/search backend unavailable — may return 500 or timeout
- Claim is in a language other than English — may produce incomplete results

## How this service works

Fact-check a claim by searching for evidence online

## Output

Returns a verification assessment of the submitted claim along with up to the requested number of online sources that provide evidence either supporting or contradicting the claim.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "claim": {
   "type": "string",
   "description": "The factual claim to verify (e.g., 'The Eiffel Tower is 330 meters tall')"
  },
  "max_sources": {
   "type": "number",
   "description": "Maximum number of sources to return (default: 5, max: 10)"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fact-checker-api-klymax402-a34c4452/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fact-checker.api.klymax402.com](https://www.zero.xyz/host/fact-checker.api.klymax402.com/llms.txt)