# Evidence Fingerprint & Claim Verification

> Evidence Fingerprint & Claim Verification is a paid API for AI agents from x402-gateway-production-1f21.up.railway.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-22).

Fetches a webpage and deterministically verifies whether specified claims are supported by the page content, returning a fingerprint for evidentiary use.

## Facts

- Endpoint: POST https://x402-gateway-production-1f21.up.railway.app/commerce/evidence-fingerprint?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/evidence-fingerprint-claim-verification-ab16fa74
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_s2J3hI6PBg1-Wv5Xs-1lP

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 evidence-fingerprint-claim-verification-ab16fa74 -d '<json body>'
```

Example prompt: Check whether the Wikipedia page at https://en.wikipedia.org/wiki/Bitcoin actually supports these two claims: 'Bitcoin was created in 2009' and 'Satoshi Nakamoto is the pseudonymous creator' — and give me a fingerprint I can use as evidence.

## When to prefer this

Choose this endpoint when you need machine-verifiable, deterministic proof that a specific URL supports a stated claim — especially for compliance auditing, fact-checking pipelines, legal evidence gathering, or RAG ingestion workflows where source attribution must be verifiable. Prefer it over generic scraping endpoints when the output must serve as structured evidence rather than raw content.

## Known failure modes

- Source URL is unreachable or returns non-200 status — claim verification fails with connectivity error
- URL points to a paywalled or bot-blocked page — content cannot be extracted
- Claims array is empty or exceeds 20 items — schema validation error
- Claim text exceeds 600 characters per item — rejected by input schema
- Page content is dynamic/JS-rendered and differs from raw HTTP response — claims may not match
- Malformed URI in source_url field — immediate validation rejection

## How this service works

Machine-payable x402 utilities for hashing, Base64, UUID generation, unit and timezone conversion, realtime crypto market data, webpage/document extraction, URL-to-Markdown, metadata, RAG ingestion and deterministic website change detection.

## Output

Returns a JSON object with status 'ready' and evidence fingerprint data indicating which claims were found supported in the fetched page content, usable as tamper-evident proof of webpage state at call time.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "source_url",
      "claims"
     ],
     "properties": {
      "claims": {
       "type": "array",
       "items": {
        "type": "string",
        "maxLength": 600
       },
       "maxItems": 20,
       "minItems": 1
      },
      "source_url": {
       "type": "string",
       "format": "uri"
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "status": "ready"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/evidence-fingerprint-claim-verification-ab16fa74/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-gateway-production-1f21.up.railway.app](https://www.zero.xyz/host/x402-gateway-production-1f21.up.railway.app/llms.txt)