Blockchain Data · x402

Receipt verification: read-only hash-chain verification of one existing Kairostamp rece…

Receipt verification: read-only hash-chain verification of one existing Kairostamp receipt id. Recomputes the canonical SHA-256 digest, compares it with the stored chain hash, checks linkage to the preceding entry and reports whether the entry is covered by a…

by kairostamp.com · discovered, not yet claimed by its owner · updated 2026-08-23

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

Tags: bazaar · builder-code · eip2612GasSponsoring · erc20ApprovalGasSponsoring

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/12354.json for the price and payment options.
Pay. Call GET https://kairostamp.com/api/v1/verify. 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, and an x402-capable client (see the examples below). Call the endpoint unpaid first to see exactly what it asks for.

Pricing & payment

Price: $0.001 / request
Protocol: x402 v2
Auth: No account or API key. Pay per request.
Networks: Base
Calls (30d): 1 · 1 unique payers (third-party data from the public x402 Bazaar)

x402 payment requirements

Scheme	Network	Asset	Amount	Pay to	Timeout
exact	Base eip155:8453	USDC	$0.001	0xdB6F694aE695C632C82677a50593B46137808453	300s

accepts[] (raw JSON)

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xdB6F694aE695C632C82677a50593B46137808453",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "amountUsd": 0.001,
    "maxTimeoutSeconds": 300
  }
]

Schemas

Output schema (JSON Schema)

{
  "bazaar": {
    "info": {
      "input": {
        "method": "GET",
        "queryParams": {
          "receipt_id": "85cd424c-b68b-440e-8f4f-e02147799f30"
        },
        "type": "http"
      },
      "output": {
        "example": {
          "anchor": {
            "chain_seq": 14,
            "covered": true,
            "network": "eip155:84532",
            "note": "Checkpoints record a chain hash only; anchoring is not a guarantee of availability, accuracy or legal effect.",
            "status": "confirmed"
          },
          "chain": {
            "chain_hash": "d084fff3e5d852089814f7d4d3ffe9d04d1a39ce9d2e0573a95f24cf78fb584d",
            "chain_seq": 12,
            "linked": true,
            "previous_chain_hash": "da27fe24efc04330962d1b95c7929a9de901ad0ea49a7997edf9f2731bf88def"
          },
          "codes": [],
          "exists": true,
          "method": "recomputed_digest",
          "receipt_id": "85cd424c-b68b-440e-8f4f-e02147799f30",
          "verdict": "valid"
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "method": {
              "enum": [
                "GET"
              ],
              "type": "string"
            },
            "queryParams": {
              "additionalProperties": false,
              "examples": [
                {
                  "receipt_id": "85cd424c-b68b-440e-8f4f-e02147799f30"
                }
              ],
              "properties": {
                "receipt_id": {
                  "description": "Identifier of a receipt previously returned by a Kairostamp paid endpoint. Sent as the `receipt_id` query parameter.",
                  "examples": [
                    "85cd424c-b68b-440e-8f4f-e02147799f30"
                  ],
                  "format": "uuid",
                  "type": "string"
                }
              },
              "required": [
                "receipt_id"
              ],
              "type": "object"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "properties": {
                "anchor": {
                  "properties": {
                    "chain_seq": {
                      "type": [
                        "integer",
                        "null"
                      ]
                    },
                    "covered": {
                      "description": "True when a checkpoint covers this entry.",
                      "type": "boolean"
                    },
                    "network": {
                      "type": [
                        "string",
                        "null"
                      ]
                    },
                    "note": {
                      "type": "string"
                    },
                    "status": {
                      "type": [
                        "string",
                        "null"
                      ]
                    }
                  },
                  "required": [
                    "covered"
                  ],
                  "type": "object"
                },
                "chain": {
                  "properties": {
                    "chain_hash": {
                      "type": [
                        "string",
                        "null"
                      ]
                    },
                    "chain_seq": {
                      "type": "integer"
                    },
                    "linked": {
                      "description": "True when the stored previous hash matches the preceding entry.",
                      "type": [
                        "boolean",
                        "null"
                      ]
                    },
                    "previous_chain_hash": {
                      "type": [
                        "string",
                        "null"
                      ]
                    }
                  },
                  "required": [
                    "chain_seq",
                    "chain_hash",
                    "previous_chain_hash",
                    "linked"
                  ],
                  "type": "object"
                },
                "codes": {
                  "items": {
                    "type": "string"
                  },
                  "type": "array"
                },
                "exists": {
                  "type": "boolean"
                },
                "method": {
                  "description": "Verification method used.",
                  "type": "string"
                },
                "receipt_id": {
                  "format": "uuid",
                  "type": "string"
                },
                "verdict": {
                  "description": "Result of recomputing the canonical digest for this entry.",
                  "enum": [
                    "valid",
                    "invalid",
                    "indeterminate",
                    "quarantined_legacy"
                  ],
                  "type": "string"
                }
              },
              "required": [
                "receipt_id",
                "exists",
                "verdict",
                "chain"
              ],
              "type": "object"
            },
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  },
  "builder-code": {
    "info": {
      "s": [
        "cdp_sdk_server"
      ]
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "additionalProperties": false,
      "properties": {
        "a": {
          "description": "App builder code",
          "pattern": "^[a-z0-9_]{1,32}$",
          "type": "string"
        },
        "s": {
          "description": "Service builder codes",
          "items": {
            "pattern": "^[a-z0-9_]{1,32}$",
            "type": "string"
          },
          "maxItems": 11,
          "type": "array"
        },
        "w": {
          "description": "Wallet builder code",
          "pattern": "^[a-z0-9_]{1,32}$",
          "type": "string"
        }
      },
      "type": "object"
    }
  },
  "eip2612GasSponsoring": {},
  "erc20ApprovalGasSponsoring": {}
}

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

null

Examples

curl

curl "https://kairostamp.com/api/v1/verify"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

JavaScript

const res = await fetch("https://kairostamp.com/api/v1/verify");
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://kairostamp.com/api/v1/verify")
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: kairostamp.com
Endpoint: https://kairostamp.com/api/v1/verify
Machine-readable: /resources/12354.json