# TruthPal Claim Verification

> TruthPal Claim Verification is a paid API for AI agents from api.thetruthpal.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-10).

Evaluates a factual claim against a provided source URL and returns a structured verdict with confidence score, reasoning, and supporting/contradicting evidence

## Facts

- Endpoint: POST https://api.thetruthpal.com/v1/verify?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/truthpal-claim-verification-200269ae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Y8FWntG0UZySo0O0F90Su

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 truthpal-claim-verification-200269ae -d '<json body>'
```

Example prompt: Can you fact-check this claim — 'The Moon is approximately 4.5 billion years old' — against this NASA article: https://moon.nasa.gov/moon-in-motion/overview/ and tell me if the source actually supports it?

## When to prefer this

Choose TruthPal when you need a structured, evidence-backed verdict on a specific factual claim tied to a particular source URL — especially when validating AI-generated content, citations, or news claims. Prefer this over generic search or web-scraping when you need not just a yes/no but also a confidence score, extracted supporting quotes, and explicit reasoning. Best when both a claim and a verifiable public source are already known.

## Known failure modes

- Source URL is inaccessible, behind a paywall, or returns a non-200 response — verdict cannot be generated
- Claim is too vague or ambiguous for the system to evaluate against the source
- Source content is not in a machine-readable format (e.g. PDF, behind JavaScript rendering)
- Claim is entirely outside the scope of the source content, resulting in an 'uncertain' verdict with low confidence
- Malformed input — missing claim or source_url fields returns a validation error

## How this service works

TruthPal: source-grounded claim verification for AI agents. Supported, contradicted or uncertain verdicts with exact source evidence. $0.02 USDC per request via x402 on Base.

## Output

A JSON object containing: a verdict string (e.g. 'true', 'false', 'uncertain'), a natural-language reasoning explanation, a confidence score between 0 and 1, a source_freshness indicator, an array of supporting_evidence quotes from the source, and an array of contradicting_evidence quotes from the source

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "claim": {
   "type": "string",
   "maxLength": 2000,
   "minLength": 5,
   "description": "The factual claim to evaluate. Leading and trailing whitespace is trimmed before validation."
  },
  "source_url": {
   "type": "string",
   "format": "uri",
   "pattern": "^[Hh][Tt][Tt][Pp][Ss]?://",
   "maxLength": 2048,
   "description": "The credential-free public HTTP or HTTPS source containing the evidence to evaluate."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "verdict": "supported",
  "evidence": [
   "The source states that the Moon formed about 4.5 billion years ago."
  ],
  "reasoning": "The source directly supports the claim that the Moon formed several billion years ago.",
  "confidence": 0.94,
  "source_freshness": "current",
  "supporting_evidence": [
   "The source states that the Moon formed about 4.5 billion years ago."
  ],
  "contradicting_evidence": []
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/truthpal-claim-verification-200269ae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.thetruthpal.com](https://www.zero.xyz/host/api.thetruthpal.com/llms.txt)