# Citation Claim Verifier

> Citation Claim Verifier is a paid API for AI agents from red-breeze-8b8c.keenanbooker83.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Verifies whether a cited source URL actually supports a specific factual claim

## Facts

- Endpoint: POST https://red-breeze-8b8c.keenanbooker83.workers.dev/verify-citation
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/citation-claim-verifier-0dcd0a54
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__AXfngcsIs_oyF6l8Tz83

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 citation-claim-verifier-0dcd0a54 -d '<json body>'
```

Example prompt: Can you check whether this source actually backs up my claim? The claim is: 'Global average temperatures have risen by 1.1°C since pre-industrial times' and the source URL is https://www.ipcc.ch/report/ar6/wg1/. I need to know if the source genuinely supports that exact statement.

## When to prefer this

Use this endpoint when you need to verify that a specific citation actually supports a precise factual claim — ideal for pre-publication fact-checking, academic citation audits, or validating arguments before use. Prefer this over a general fact-checker when you already have both the claim and the source URL, and need a binary or graded judgment about whether the source justifies the claim. Choose this over the statistical-claim evaluator when the claim is a general fact rather than a statistical assertion.

## Known failure modes

- Source URL is paywalled or access-restricted — cannot retrieve content to verify
- URL returns 404 or is otherwise unavailable
- Claim text is too vague or ambiguous to test against a source
- Source is a non-text format (e.g. video, audio) that cannot be parsed
- Rate limiting or network errors prevent source retrieval
- Claim exceeds 4000 character limit
- Source URL exceeds 2048 character limit

## How this service works

Verify whether a cited source supports an exact factual claim

## Output

A structured assessment indicating whether the provided source URL supports the stated factual claim, including the degree of support (e.g. confirmed, partially supported, not supported, contradicted), relevant excerpts or reasoning from the source, and any caveats or scope mismatches between the claim and what the source actually states.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "claim": {
   "type": "string",
   "maxLength": 4000,
   "minLength": 1,
   "description": "The exact factual claim to test against the cited source."
  },
  "sourceUrl": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 1,
   "description": "Public URL of the source that allegedly supports the claim."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "result": {
   "agent": {
    "id": "citation-verification",
    "version": "2.0.0"
   },
   "claim": "The United States declared war on Japan on December 8, 1941.",
   "verification": {
    "verdict": "supported",
    "confidence": 0.98
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/citation-claim-verifier-0dcd0a54/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from red-breeze-8b8c.keenanbooker83.workers.dev](https://www.zero.xyz/host/red-breeze-8b8c.keenanbooker83.workers.dev/llms.txt)