# SafePay402 Guard - Pre-Payment Security Check

> SafePay402 Guard - Pre-Payment Security Check is a paid API for AI agents from guard.safepay402.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-13).

Screens an x402 payment recipient and terms before funds are sent, returning an ALLOW/REVIEW/BLOCK/UNKNOWN verdict with a 0-100 risk score and named risk signals.

## Facts

- Endpoint: GET https://guard.safepay402.com/v1/guard/check
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/safepay402-guard-pre-payment-security-check-3bdb43f4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ssfi25Dh4IcBz1pG7wkVg

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 safepay402-guard-pre-payment-security-check-3bdb43f4
```

Example prompt: Before you pay, run a SafePay402 guard check on this x402 request — the resource URL is https://api.example.com/data, the payee is 0xAbC123...456, network is eip155:8453 (Base), asset is USDC, and the amount is 0.025. Tell me if I should allow, review, or block the payment.

## When to prefer this

Use this endpoint whenever an AI agent is about to autonomously send funds via the x402 protocol and needs a pre-payment safety gate. It is the only known endpoint combining OFAC sanctions screening, scam-address databases, on-chain wallet analysis on Base, live payee re-verification (anti-hijack), and behavioral history in a single call. Prefer it over generic address checkers when you need x402-specific hijack detection and explainable verdicts with named signals.

## Known failure modes

- Missing required resource_url or payee_address returns a 400 error
- Unresolvable or offline resource_url may return UNKNOWN verdict
- Unrecognized network ID may return an error or degrade signal quality
- Wallet with no on-chain history returns limited signals and likely UNKNOWN
- Service unavailability returns 503, leaving the agent without a safety verdict

## How this service works

Pre-payment security checks for x402 payments. Explainable ALLOW/REVIEW/BLOCK/UNKNOWN verdicts with risk signals, before an AI agent sends funds. The paid endpoint is monetized via the x402 protocol (USDC on Base): an unpaid request returns HTTP 402 with payment requirements.

## Output

Returns a verdict of ALLOW, REVIEW, BLOCK, or UNKNOWN, a numeric risk score from 0-100, and a list of named risk signals with sources — including OFAC sanctions hits, scam-address matches, on-chain wallet age and activity on Base, live re-verification of the 402 endpoint's current payee (detects hijacks), and behavioral flags like payee rotation or price spikes.

## 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"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "resource_url",
      "payee_address"
     ],
     "properties": {
      "asset": {
       "type": "string",
       "description": "Payment asset symbol, e.g. USDC"
      },
      "amount": {
       "type": "string",
       "description": "Payment amount in asset units, e.g. 0.025"
      },
      "policy": {
       "type": "object",
       "description": "Optional agent policy: allowed_networks[], allowed_assets[], max_amount"
      },
      "network": {
       "type": "string",
       "description": "CAIP-2 network id, e.g. eip155:8453 (Base)"
      },
      "payment_id": {
       "type": "string",
       "description": "Optional idempotency key — repeated calls return the cached verdict"
      },
      "resource_url": {
       "type": "string",
       "description": "The x402 resource URL the agent is about to pay"
      },
      "payee_address": {
       "type": "string",
       "description": "EVM address (0x…) that would receive the payment"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "signals": [
   {
    "type": "positive",
    "source": "live_probe",
    "description": "Live check: the endpoint's 402 response demands exactly this payee address"
   },
   {
    "type": "positive",
    "source": "onchain",
    "description": "Payee wallet has existed for over 10 months"
   }
  ],
  "sources": [
   "sanctions",
   "onchain",
   "live_probe",
   "historical_x402"
  ],
  "summary": "No significant risk signals. The payee and payment terms look trustworthy.",
  "verdict": "ALLOW",
  "checked_at": "2026-07-21T09:15:33Z",
  "confidence": 0.87,
  "risk_score": 12,
  "recommendation": "Payment can be executed safely.",
  "ruleset_version": "2026.07.1"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/safepay402-guard-pre-payment-security-check-3bdb43f4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from guard.safepay402.com](https://www.zero.xyz/host/guard.safepay402.com/llms.txt)