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Monitoring · x402 · early usage

x402 endpoint check: validate an x402 endpoint and audit its Bazaar listing before you…

x402 endpoint check: validate an x402 endpoint and audit its Bazaar listing before you pay for it or list it. One unpaid probe (never pays the target) grades the 402 challenge, schemas, examples, name, tags and latency, and adds Coinbase's validator verdict,…

by x402-seller-pmlm.onrender.com · discovered, not yet claimed by its owner · updated 2026-10-08

30d calls6
30d payers3
MethodGET
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

x402 endpoint check: validate an x402 endpoint and audit its Bazaar listing before you pay for it or list it. One unpaid probe (never pays the target) grades the 402 challenge, schemas, examples, name, tags and latency, and adds Coinbase's validator verdict, the live Bazaar listing (30-day calls, payers, stale metadata) and search rank for its own name and tags. Returns score, grade and prioritized fixes. 0.005 USDC/call; failed calls are free.

Tags: x402 endpoint check · validate x402 endpoint · x402 bazaar ranking · x402 listing audit · api testing · bazaar · builder-code · eip2612GasSponsoring · erc20ApprovalGasSponsoring

Call contract

Method
GET
Input
query parameters
Output
json
Last paid call
2026-10-08
Input example from Bazaar metadata
{
  "url": "https://x402-seller-pmlm.onrender.com/report"
}
Output example
{
  "bazaarListing": {
    "calls30d": 8,
    "indexedServiceName": "Research Brief with Citations",
    "indexedTags": [
      "research brief",
      "web research",
      "summarize a topic",
      "wikipedia summary",
      "answer with sources"
    ],
    "lastCalledAt": "2026-10-06T05:32:44.371Z",
    "lastUpdated": "2026-10-06T05:32:44.958Z",
    "listed": true,
    "metadataStale": [],
    "uniquePayers30d": 4
  },
  "cdpValidator": {
    "failedAdvisory": [],
    "failedRequired": [],
    "indexed": true,
    "lastCrawledAt": "2026-10-06T05:32:45.591Z",
    "simulation": "accepted",
    "valid": true
  },
  "checkedAt": "2026-10-06T07:03:04.512Z",
  "checks": [
    {
      "detail": "HTTP 402 (unpaid probe must return 402)",
      "id": "status_402",
      "pass": true,
      "severity": "required"
    },
    {
      "detail": "79 ms",
      "id": "latency_under_1500ms",
      "pass": true,
      "severity": "ranking"
    },
    {
      "detail": "Research Brief with Citations",
      "id": "service_name_set",
      "pass": true,
      "severity": "ranking"
    },
    {
      "detail": "5 tag(s): research brief, web research, summarize a topic, wikipedia summary, answer with sources",
      "id": "tags_set",
      "pass": true,
      "severity": "ranking"
    },
    {
      "detail": "extensions.bazaar present",
      "id": "bazaar_extension",
      "pass": true,
      "severity": "required"
    },
    {
      "detail": "17 top-level fields in the output example",
      "id": "output_example",
      "pass": true,
      "severity": "ranking"
    },
    {
      "detail": "required output fields present in example",
      "id": "example_matches_schema",
      "pass": true,
      "severity": "advisory"
    },
    {
      "detail": "Coinbase validator: valid=true, simulation=accepted",
      "id": "cdp_validator",
      "pass": true,
      "severity": "required"
    }
  ],
  "fixes": [],
  "grade": "A",
  "indexable": true,
  "latencyMs": 79,
  "method": "GET",
  "networks": [
    "eip155:8453",
    "eip155:137",
    "eip155:42161",
    "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "eip155:43114",
    "eip155:1329"
  ],
  "note": "One unpaid probe from this service plus Coinbase's own free validator probe; nothing is ever paid to the target. Bazaar rank = relevance (name, tags,…",
  "passed": 22,
  "priceUsdIfUsdc": 0.01,
  "score": 100,
  "searchRanks": [
    {
      "leader": {
        "calls30d": 8,
        "payers30d": 4,
        "resource": "https://x402-seller-pmlm.onrender.com/report"
      },
      "of": 9,
      "query": "Research Brief with Citations",
      "rank": 1
    },
    {
      "leader": {
        "calls30d": 8,
        "payers30d": 4,
        "resource": "https://x402-seller-pmlm.onrender.com/report"
      },
      "of": 9,
      "query": "research brief",
      "rank": 1
    },
    {
      "leader": {
        "calls30d": 2,
        "payers30d": 2,
        "resource": "https://market.datapackvibe.com/x402/demand-next-web-research-methods-researchers"
      },
      "of": 11,
      "query": "web research",
      "rank": null
    }
  ],
  "serviceName": "Research Brief with Citations",
  "target": "https://x402-seller-pmlm.onrender.com/report",
  "total": 22,
  "totalMs": 1423
}

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/28413.json for the price and payment options.
  3. Pay. Call GET https://x402-seller-pmlm.onrender.com/check. 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, Polygon, Arbitrum One, Solana, Avalanche, eip155:1329, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price
$0.005 / request
Protocol
x402 v2
Auth
No account or API key. Pay per request.
Networks
Base, Polygon, Arbitrum One, Solana, Avalanche, eip155:1329
Demand
6 calls · 3 unique payers in 30d (public x402 Bazaar data)

x402 payment requirements

SchemeNetworkAssetAmountPay toTimeout
exactBase
eip155:8453		USDC$0.0050x079471E6F43b6feeF80895E19cBFcBB496904852300s
exactPolygon
eip155:137		USDC$0.0050x079471E6F43b6feeF80895E19cBFcBB496904852300s
exactArbitrum One
eip155:42161		USDC$0.0050x079471E6F43b6feeF80895E19cBFcBB496904852300s
exactSolana
solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp		USDC$0.005787RZwDGpjmRsG5wgnyBeWQHBuARax8Qo6P7dmDuqKeW300s
exactAvalanche
eip155:43114		0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E50000x079471E6F43b6feeF80895E19cBFcBB496904852300s
exacteip155:1329
eip155:1329		0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf4239250000x079471E6F43b6feeF80895E19cBFcBB496904852300s
accepts[] (raw JSON)
[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x079471E6F43b6feeF80895E19cBFcBB496904852",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:137",
    "payTo": "0x079471E6F43b6feeF80895E19cBFcBB496904852",
    "asset": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:42161",
    "payTo": "0x079471E6F43b6feeF80895E19cBFcBB496904852",
    "asset": "0xaf88d065e77c8cC2239327C5EDb3A432268e5831",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
    "payTo": "787RZwDGpjmRsG5wgnyBeWQHBuARax8Qo6P7dmDuqKeW",
    "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
    "amount": "5000",
    "amountUsd": 0.005,
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:43114",
    "payTo": "0x079471E6F43b6feeF80895E19cBFcBB496904852",
    "asset": "0xB97EF9Ef8734C71904D8002F8b6Bc66Dd9c48a6E",
    "amount": "5000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:1329",
    "payTo": "0x079471E6F43b6feeF80895E19cBFcBB496904852",
    "asset": "0xe15fC38F6D8c56aF07bbCBe3BAf5708A2Bf42392",
    "amount": "5000",
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)
{
  "properties": {
    "example": {
      "properties": {
        "bazaarListing": {
          "description": "Live CDP Bazaar entry: listed, calls30d, uniquePayers30d, lastCalledAt, indexed name/tags, metadataStale",
          "type": "object"
        },
        "cdpValidator": {
          "description": "Coinbase /x402/validate verdict: valid, simulation, indexed, failed checks",
          "type": [
            "object",
            "null"
          ]
        },
        "checkedAt": {
          "type": "string"
        },
        "checks": {
          "items": {
            "properties": {
              "detail": {
                "type": "string"
              },
              "fix": {
                "type": "string"
              },
              "id": {
                "type": "string"
              },
              "pass": {
                "type": "boolean"
              },
              "severity": {
                "enum": [
                  "required",
                  "ranking",
                  "advisory"
                ],
                "type": "string"
              }
            },
            "type": "object"
          },
          "type": "array"
        },
        "fixes": {
          "description": "Failed checks, required first, each with a concrete fix",
          "items": {
            "type": "string"
          },
          "type": "array"
        },
        "grade": {
          "enum": [
            "A",
            "B",
            "C",
            "D",
            "F"
          ],
          "type": "string"
        },
        "indexable": {
          "type": "boolean"
        },
        "latencyMs": {
          "type": "integer"
        },
        "networks": {
          "items": {
            "type": "string"
          },
          "type": "array"
        },
        "passed": {
          "type": "integer"
        },
        "priceUsdIfUsdc": {
          "type": [
            "number",
            "null"
          ]
        },
        "score": {
          "maximum": 100,
          "minimum": 0,
          "type": "integer"
        },
        "searchRanks": {
          "description": "Bazaar search position for the endpoint's own serviceName and first tags",
          "items": {
            "properties": {
              "leader": {
                "type": [
                  "object",
                  "null"
                ]
              },
              "of": {
                "type": "integer"
              },
              "query": {
                "type": "string"
              },
              "rank": {
                "type": [
                  "integer",
                  "null"
                ]
              }
            },
            "type": "object"
          },
          "type": "array"
        },
        "serviceName": {
          "type": [
            "string",
            "null"
          ]
        },
        "target": {
          "type": "string"
        },
        "total": {
          "type": "integer"
        },
        "totalMs": {
          "type": "integer"
        }
      },
      "required": [
        "target",
        "score",
        "grade",
        "checks",
        "fixes"
      ],
      "type": "object"
    },
    "type": {
      "type": "string"
    }
  },
  "required": [
    "type"
  ],
  "type": "object"
}
Example shape — generated from the schema, not a captured live response
{
  "example": {
    "bazaarListing": {},
    "cdpValidator": {},
    "checkedAt": "string",
    "checks": [
      {
        "detail": "string",
        "fix": "string",
        "id": "string",
        "pass": true,
        "severity": "required"
      }
    ],
    "fixes": [
      "string"
    ],
    "grade": "A",
    "indexable": true,
    "latencyMs": 0,
    "networks": [
      "string"
    ],
    "passed": 0,
    "priceUsdIfUsdc": 0,
    "score": 0,
    "searchRanks": [
      {
        "leader": {},
        "of": 0,
        "query": "string",
        "rank": 0
      }
    ],
    "serviceName": "string",
    "target": "string",
    "total": 0,
    "totalMs": 0
  },
  "type": "string"
}

Examples

curl
curl "https://x402-seller-pmlm.onrender.com/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-seller-pmlm.onrender.com/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-seller-pmlm.onrender.com/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-seller-pmlm.onrender.com
Endpoint
https://x402-seller-pmlm.onrender.com/check
Machine-readable
/resources/28413.json