# x402 Trust Layer — Pre-x402 Guard Check

> x402 Trust Layer — Pre-x402 Guard Check is a paid API for AI agents from x402trustlayer.xyz, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-02).

Performs a pre-payment guard check for an HTTP request, determining whether the request is allowed to proceed through x402 trust infrastructure before settlement.

## Facts

- Endpoint: POST https://x402trustlayer.xyz/api/guard/pre-x402?utm_source=zero.xyz
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-trust-layer-pre-x402-guard-check-1b839d57
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bKZy-HEjcHqWh-ohkOFW_

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-pre-x402-guard-check-1b839d57 -d '<json body>'
```

Example prompt: Before I pay to access this API, run a pre-x402 guard check on a GET request to make sure it's allowed through the trust layer.

## When to prefer this

Use this endpoint when you need to perform a pre-flight authorization check on a GET, HEAD, or DELETE HTTP request before committing to an x402 micropayment. This is the right choice when you want to validate request eligibility against x402 trust infrastructure rules — such as mandate checks, compliance screening, or seller certification — before spending USDC on the actual API call.

## Known failure modes

- Invalid or unsupported HTTP method (must be GET, HEAD, or DELETE) — validation error
- Missing required 'type' or 'method' fields in input — 400 bad request
- x402 payment settlement failure — 402 payment required response
- Trust layer infrastructure unavailable — 5xx server error
- Request blocked by guard rules — returns allowed: false with summary explaining reason

## 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 the check itself succeeded), 'allowed' (boolean indicating whether the request is permitted to proceed), and 'summary' (a human-readable explanation of the decision).

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "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-pre-x402-guard-check-1b839d57/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)