Monitoring · x402 · active demand

Source-bounded fact-check

Source-bounded fact-check. Verify a claim against provided source text. Returns verdict: supported, contradicted, or unverifiable. Does NOT search the web.

by x402.asterpay.io · discovered, not yet claimed by its owner · updated 2026-10-13

30d calls31

30d payers14

MethodPOST

Outputjson

Mirrored from Coinbase's public x402 Bazaar. The description is the provider's own text and has not been reviewed here; the payment requirements are copied as published.

What it does

Source-bounded fact-check. Verify a claim against provided source text. Returns verdict: supported, contradicted, or unverifiable. Does NOT search the web.

Tags: bazaar · payment-identifier

Call contract

Method: POST
Input: json
Output: json
Last paid call: 2026-10-13

Input example from Bazaar metadata

{
  "claim": "Apple reported revenue of $94.9 billion in Q1 2024",
  "source": "Apple Inc. reported fiscal first-quarter revenue of $119.6 billion, a new record."
}

Output example

{
  "claims_checked": 1,
  "confidence": 0.98,
  "evidence": "Source states $119.6B, not $94.9B as claimed.",
  "latency_ms": 820,
  "model": "llama-3.3-70b-versatile",
  "summary": "Revenue figure directly contradicted by source.",
  "verdict": "contradicted"
}

Use with an agent

Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
Inspect. Fetch /resources/28956.json for the price and payment options.
Pay. Call GET https://x402.asterpay.io/v2/x402/ai/fact-check. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
Execute. The provider returns 200 with the data. Agent Bazaar is not in the request path and never sees your payment.

For humans

You don't need an account or an API key; you need a wallet holding a small amount of USDC on Base, Polygon, Arbitrum One, Optimism, Ethereum, eip155:1187947933, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price: $0.015 / request
Protocol: x402 v2
Auth: No account or API key. Pay per request.
Networks: Base, Polygon, Arbitrum One, Optimism, Ethereum, eip155:1187947933
Demand: 31 calls · 14 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

Scheme	Network	Asset	Amount	Pay to	Timeout
exact	Base eip155:8453	USDC	$0.015	0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E	300s
exact	Polygon eip155:137	USDC	$0.015	0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E	300s
exact	Arbitrum One eip155:42161	USDC	$0.015	0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E	300s
exact	Optimism eip155:10	0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85	15000	0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E	300s
exact	Ethereum eip155:1	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	15000	0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E	300s
exact	eip155:1187947933 eip155:1187947933	0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20	15000	0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E	300s

accepts[] (raw JSON)

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "15000",
    "amountUsd": 0.015,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:137",
    "payTo": "0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E",
    "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "amount": "15000",
    "amountUsd": 0.015,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42161",
    "payTo": "0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E",
    "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "amount": "15000",
    "amountUsd": 0.015,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:10",
    "payTo": "0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E",
    "asset": "0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85",
    "amount": "15000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:1",
    "payTo": "0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E",
    "asset": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    "amount": "15000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:1187947933",
    "payTo": "0xd5f8481D8F25d3966d2010DBf9B47fFbdf745A9E",
    "asset": "0x85889c8c714505E0c94b30fcfcF64fE3Ac8FCb20",
    "amount": "15000",
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)

{
  "properties": {
    "example": {
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}

Example shape — generated from the schema, not a captured live response

{
  "example": {},
  "type": "string"
}

Examples

curl

curl "https://x402.asterpay.io/v2/x402/ai/fact-check"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

JavaScript

const res = await fetch("https://x402.asterpay.io/v2/x402/ai/fact-check");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

Python

import httpx
res = httpx.get("https://x402.asterpay.io/v2/x402/ai/fact-check")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header

Details

Provider: x402.asterpay.io
Endpoint: https://x402.asterpay.io/v2/x402/ai/fact-check
Machine-readable: /resources/28956.json