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Security · x402 · early usage

Fact check claims against sources: up to 10 claims checked against up to 4 source URLs…

Fact check claims against sources: up to 10 claims checked against up to 4 source URLs you name; each comes back SUPPORTED, CONTRADICTED or UNSUPPORTED with the exact quote the verdict rests on. Use it to verify AI output, citations or statements before publi…

by hubvibe-io.com · discovered, not yet claimed by its owner · updated 2026-10-01

30d calls3
30d payers1
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

Fact check claims against sources: up to 10 claims checked against up to 4 source URLs you name; each comes back SUPPORTED, CONTRADICTED or UNSUPPORTED with the exact quote the verdict rests on. Use it to verify AI output, citations or statements before publishing. Input: claims[], sources[]. A question but no sources yet: research.web.

Tags: fact-check · verification · claims · citations · hallucination-check · bazaar

Call contract

Method
POST
Input
json
Output
json
Last paid call
2026-10-01
Input example from Bazaar metadata
{
  "claims": [
    "HubVibe sells machine-payable site audits."
  ],
  "sources": [
    "https://example.com"
  ]
}
Output example
{
  "attribution": [
    {
      "text": "Translated by Google",
      "url": "https://translate.google.com"
    }
  ],
  "price_usd": 5,
  "provenance": {
    "attempts": 1,
    "elapsed_ms": 340,
    "providers_used": [
      "coinbase-advanced-trade-public"
    ],
    "steps": [
      {
        "ms": 312,
        "ok": true,
        "provider": "coinbase-advanced-trade-public",
        "reason": "provider_timeout",
        "step": "quote"
      }
    ]
  },
  "receipt_id": "rcpt_9f1c2b3a4d5e6f70",
  "receipt_url": "/work/receipts/rcpt_9f1c2b3a4d5e6f70",
  "result": {
    "claims": [
      "HubVibe sells machine-payable site audits."
    ],
    "model": "gemini-2.5-flash",
    "sources_read": [
      {
        "n": 1,
        "title": "About Example",
        "url": "https://example.com/about"
      }
    ],
    "sources_unread": [],
    "verdicts": [
      {
        "claim": "HubVibe sells machine-payable site audits.",
        "quote": "Every check is priced per call over HTTP 402.",
        "source_n": 1,
        "verdict": "SUPPORTED"
      }
    ]
  },
  "status": "ok",
  "worker": "verify.claims"
}

Use with an agent

  1. Discover. Agents find this listing with GET https://bazaar.saylorinnovations.com/discovery/search?query=…, the MCP tool search_resources, or /discovery/resources.
  2. Inspect. Fetch /resources/32921.json for the price and payment options.
  3. Pay. Call GET https://hubvibe-io.com/work/verify/claims. The provider answers 402 with its payment requirements. An x402 client signs one of the options below and retries with PAYMENT-SIGNATURE.
  4. 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, Solana, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price
$5 / request
Protocol
x402 v2
Auth
No account or API key. Pay per request.
Networks
Base, Solana
Demand
3 calls · 1 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

SchemeNetworkAssetAmountPay toTimeout
exactBase
eip155:8453		USDC$50x837C40E2B4e976f43Ffb4451eE281A00fA9477dd300s
exactSolana
solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp		USDC$5J1K4mdbvXEbJLRKpgxFcA7s66LWMCYHu71ye6Hz2icSh300s
accepts[] (raw JSON)
[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x837C40E2B4e976f43Ffb4451eE281A00fA9477dd",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "5000000",
    "amountUsd": 5,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "J1K4mdbvXEbJLRKpgxFcA7s66LWMCYHu71ye6Hz2icSh",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "5000000",
    "amountUsd": 5,
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)
{
  "properties": {
    "example": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "attribution": {
          "items": {
            "properties": {
              "text": {
                "type": "string"
              },
              "url": {
                "type": "string"
              }
            },
            "required": [
              "text",
              "url"
            ],
            "type": "object"
          },
          "type": "array"
        },
        "billing_warning": {
          "type": "string"
        },
        "price_usd": {
          "type": "number"
        },
        "provenance": {
          "properties": {
            "attempts": {
              "type": "integer"
            },
            "elapsed_ms": {
              "type": "integer"
            },
            "providers_used": {
              "items": {
                "type": "string"
              },
              "type": "array"
            },
            "steps": {
              "items": {
                "properties": {
                  "ms": {
                    "type": "integer"
                  },
                  "ok": {
                    "type": "boolean"
                  },
                  "provider": {
                    "type": "string"
                  },
                  "reason": {
                    "type": "string"
                  },
                  "step": {
                    "type": "string"
                  }
                },
                "required": [
                  "step",
                  "ok",
                  "ms"
                ],
                "type": "object"
              },
              "type": "array"
            }
          },
          "required": [
            "steps",
            "providers_used",
            "attempts",
            "elapsed_ms"
          ],
          "type": "object"
        },
        "receipt_id": {
          "type": "string"
        },
        "receipt_url": {
          "type": "string"
        },
        "result": {
          "properties": {
            "claims": {
              "items": {
                "type": "string"
              },
              "type": "array"
            },
            "model": {
              "type": "string"
            },
            "sources_read": {
              "items": {
                "properties": {
                  "n": {
                    "type": "integer"
                  },
                  "url": {
                    "type": "string"
                  }
                },
                "required": [
                  "n",
                  "url"
                ],
                "type": "object"
              },
              "type": "array"
            },
            "sources_unread": {
              "items": {
                "properties": {
                  "reason": {
                    "type": "string"
                  },
                  "url": {
                    "type": "string"
                  }
                },
                "required": [
                  "url",
                  "reason"
                ],
                "type": "object"
              },
              "type": "array"
            },
            "verdicts": {
              "items": {
                "properties": {
                  "claim": {
                    "type": "string"
                  },
                  "quote": {
                    "type": [
                      "string",
                      "null"
                    ]
                  },
                  "source_n": {
                    "type": [
                      "integer",
                      "null"
                    ]
                  },
                  "verdict": {
                    "enum": [
                      "SUPPORTED",
                      "CONTRADICTED",
                      "UNSUPPORTED"
                    ],
                    "type": "string"
                  }
                },
                "required": [
                  "claim",
                  "verdict"
                ],
                "type": "object"
              },
              "type": "array"
            }
          },
          "required": [
            "claims",
            "verdicts",
            "sources_read",
            "sources_unread",
            "model"
          ],
          "type": "object"
        },
        "status": {
          "const": "ok",
          "type": "string"
        },
        "worker": {
          "type": "string"
        }
      },
      "required": [
        "status",
        "worker",
        "price_usd",
        "result",
        "provenance",
        "receipt_id",
        "receipt_url"
      ],
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}
Example shape — generated from the schema, not a captured live response
{
  "example": {
    "attribution": [
      {
        "text": "string",
        "url": "string"
      }
    ],
    "billing_warning": "string",
    "price_usd": 0,
    "provenance": {
      "attempts": 0,
      "elapsed_ms": 0,
      "providers_used": [
        "string"
      ],
      "steps": [
        {
          "ms": 0,
          "ok": true,
          "provider": "string",
          "reason": "string",
          "step": "string"
        }
      ]
    },
    "receipt_id": "string",
    "receipt_url": "string",
    "result": {
      "claims": [
        "string"
      ],
      "model": "string",
      "sources_read": [
        {
          "n": 0,
          "url": "string"
        }
      ],
      "sources_unread": [
        {
          "reason": "string",
          "url": "string"
        }
      ],
      "verdicts": [
        {
          "claim": "string",
          "quote": "string",
          "source_n": 0,
          "verdict": "SUPPORTED"
        }
      ]
    },
    "status": "string",
    "worker": "string"
  },
  "type": "string"
}

Examples

curl
curl "https://hubvibe-io.com/work/verify/claims"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid
JavaScript
const res = await fetch("https://hubvibe-io.com/work/verify/claims");
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://hubvibe-io.com/work/verify/claims")
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
hubvibe-io.com
Endpoint
https://hubvibe-io.com/work/verify/claims
Machine-readable
/resources/32921.json