# x402 Trust Layer - Replay Verification

> x402 Trust Layer - Replay Verification is a paid API for AI agents from x402trustlayer.xyz, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-12).

Verifies whether an HTTP request has already been replayed or settled within the x402 trust protocol, returning an allow/deny decision with a summary.

## Facts

- Endpoint: POST https://x402trustlayer.xyz/api/protocol/replay/verify?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-trust-layer-replay-verification-10eb25cf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ta0cxrUEtvhYPLxo4g_EZ

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-trust-layer-replay-verification-10eb25cf -d '<json body>'
```

Example prompt: Can you verify this POST request with a JSON body against the x402 trust layer to make sure it hasn't already been replayed or double-submitted?

## When to prefer this

Use this endpoint when you need to detect and prevent replay attacks within the x402 payment protocol ecosystem, specifically for POST, PUT, or PATCH HTTP requests. Prefer this over generic idempotency checks when operating within x402 trust infrastructure and needing a certified allow/deny decision backed by the trust layer's mandate and compliance systems.

## Known failure modes

- Missing required 'type', 'method', 'bodyType', or 'body' fields returns validation error
- Unsupported method (e.g. GET or DELETE) rejected by enum constraint
- Invalid bodyType outside json/form-data/text causes schema rejection
- Replay detected returns allowed:false with explanatory summary
- Payment not settled via x402 results in 402 Payment Required response
- Network or infrastructure timeout returns non-ok response

## How this service works

68 paid x402 trust infrastructure APIs: guard, semantic escrow, mandate diff, certified seller network, KYM, mandates, compliance, disputes, and orchestration.

## Output

Returns a JSON object with 'ok' (boolean indicating successful verification call), 'allowed' (boolean indicating whether the request is permitted or flagged as a replay), and 'summary' (a human-readable string explaining the outcome after x402 settlement check).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "ok",
      "allowed",
      "summary"
     ],
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "allowed": {
       "type": "boolean"
      },
      "summary": {
       "type": "string"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "allowed": true,
  "summary": "Paid response after x402 settlement"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-trust-layer-replay-verification-10eb25cf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402trustlayer.xyz](https://www.zero.xyz/host/x402trustlayer.xyz/llms.txt)