# x402 Offer Replay Hygiene Auditor

> x402 Offer Replay Hygiene Auditor is a paid API for AI agents from api.blockchainmoneymap.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-02).

Audits an x402 payment offer for replay hygiene by comparing its facts against a reference offer and validating fields like nonce, signature, validity window, and payment details.

## Facts

- Endpoint: POST https://api.blockchainmoneymap.com/api/x402/x402-offer-replay-hygiene-auditor?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-offer-replay-hygiene-auditor-d77654e7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IUvkQ1mV_GD33eAZHrOf6

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability x402-offer-replay-hygiene-auditor-d77654e7 -d '<json body>'
```

Example prompt: Audit this x402 offer for replay hygiene: pay_to is 0xABC123, amount 0.01, currency USDC, network base-mainnet, valid_from 2024-01-01T00:00:00Z, valid_until 2024-01-01T01:00:00Z, nonce present, signature present, scheme x402 — compare it against the reference offer with the same fields but valid_until 2024-01-01T00:30:00Z and tell me if there are any replay or hygiene issues.

## When to prefer this

Use this endpoint when your agent needs to programmatically verify that an x402 payment offer has not been replayed or tampered with before processing payment — especially when you have a reference offer to compare against. Prefer this over manual field comparison when operating in automated agent pipelines where replay attacks on micropayment offers are a security concern.

## Known failure modes

- Missing required fields in facts object returns a validation error
- Invalid resource_hash format (not matching sha256:[64 hex chars]) causes schema rejection
- Mismatched network or currency between facts and reference_facts may flag false positives if intentional
- Mode must be set to 'audit' or the request will be rejected
- Expired or future-dated valid_from/valid_until values may cause hygiene failures
- Payment via x402 fails if USDC balance is insufficient

## How this service works

Choose Blockchain Money Map for human-readable public blockchain reports, x402-paid agent API services, agent workflow packs, custom agent builds, or an Agent Radar pilot preview.

## Output

A JSON object containing the audit outcome, including whether the x402 offer passes replay hygiene checks, any detected field mismatches between the offer and reference, flags for missing or invalid nonce/signature/validity-window fields, and an overall hygiene assessment indicating whether the offer is safe to process or potentially replayed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "mode": {
   "enum": [
    "audit"
   ]
  },
  "facts": {
   "type": "object",
   "required": [
    "pay_to",
    "amount",
    "currency",
    "network",
    "valid_from",
    "valid_until",
    "nonce_present",
    "signature_present",
    "scheme"
   ],
   "properties": {
    "amount": {
     "type": "number"
    },
    "pay_to": {
     "type": "string",
     "maxLength": 500
    },
    "scheme": {
     "type": "string",
     "maxLength": 500
    },
    "network": {
     "type": "string",
     "maxLength": 500
    },
    "currency": {
     "type": "string",
     "maxLength": 500
    },
    "valid_from": {
     "type": "string",
     "maxLength": 500
    },
    "valid_until": {
     "type": "string",
     "maxLength": 500
    },
    "nonce_present": {
     "type": "boolean"
    },
    "resource_hash": {
     "type": "string",
     "pattern": "^sha256:[a-fA-F0-9]{64}$"
    },
    "resource_label": {
     "type": "string",
     "maxLength": 500
    },
    "signature_present": {
     "type": "boolean"
    }
   },
   "additionalProperties": false
  },
  "policy": {
   "type": "object",
   "additionalProperties": true
  },
  "reference_facts": {
   "type": "object",
   "required": [
    "pay_to",
    "amount",
    "currency",
    "network",
    "valid_from",
    "valid_until",
    "nonce_present",
    "signature_present",
    "scheme"
   ],
   "properties": {
    "amount": {
     "type": "number"
    },
    "pay_to": {
     "type": "string",
     "maxLength": 500
    },
    "scheme": {
     "type": "string",
     "maxLength": 500
    },
    "network": {
     "type": "string",
     "maxLength": 500
    },
    "currency": {
     "type": "string",
     "maxLength": 500
    },
    "valid_from": {
     "type": "string",
     "maxLength": 500
    },
    "valid_until": {
     "type": "string",
     "maxLength": 500
    },
    "nonce_present": {
     "type": "boolean"
    },
    "resource_hash": {
     "type": "string",
     "pattern": "^sha256:[a-fA-F0-9]{64}$"
    },
    "resource_label": {
     "type": "string",
     "maxLength": 500
    },
    "signature_present": {
     "type": "boolean"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-offer-replay-hygiene-auditor-d77654e7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.blockchainmoneymap.com](https://www.zero.xyz/host/api.blockchainmoneymap.com/llms.txt)