Pay-per-call: Multi-Chain Gas Tracker

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xf16F0882de08315B438E9f3a2Abfb2d2E5d94ECA",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "maxTimeoutSeconds": 120
  }
]

{
  "bazaar": {
    "info": {
      "input": {
        "body": {
          "id": 1,
          "jsonrpc": "2.0",
          "method": "tools/call",
          "params": {
            "arguments": {},
            "name": "<the seller's tool>"
          }
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "example": {
          "note": "The seller's own response, passed through unchanged. Settlement headers are added: X-FiatDock-Settlement (tx hashes), X-FiatDock-Fee-Bps, and X-FiatDock-Receipt (proof-of-purchase for a review)."
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "body": {
              "properties": {
                "jsonrpc": {
                  "description": "\"2.0\" — the body is forwarded VERBATIM to the seller's MCP endpoint, so send whatever that server expects",
                  "type": "string"
                },
                "method": {
                  "description": "e.g. tools/call",
                  "type": "string"
                },
                "params": {
                  "description": "the seller's own tool name + arguments",
                  "type": "object"
                }
              },
              "required": []
            },
            "bodyType": {
              "enum": [
                "json",
                "form-data",
                "text"
              ],
              "type": "string"
            },
            "method": {
              "enum": [
                "POST",
                "PUT",
                "PATCH"
              ],
              "type": "string"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method",
            "bodyType",
            "body"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "type": "object"
            },
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  }
}

curl "https://fiatdock.com/s/svc_c815b4e9-36bd-4cdc-8eee-1be968cde5c2"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://fiatdock.com/s/svc_c815b4e9-36bd-4cdc-8eee-1be968cde5c2");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://fiatdock.com/s/svc_c815b4e9-36bd-4cdc-8eee-1be968cde5c2")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header