# PayPerByte Merchant Screen — x402 Pre-Settlement Verification

> PayPerByte Merchant Screen — x402 Pre-Settlement Verification is a paid API for AI agents from x402.payperbyte.io, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-14).

Returns a cryptographically signed ALLOW/WARN/BLOCK verdict on an (domain, payTo address, observed price) triple before an AI agent settles an x402 payment

## Facts

- Endpoint: POST https://x402.payperbyte.io/feeds/merchant-screen
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/payperbyte-merchant-screen-x402-pre-settlement-verification-afa0abd4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0wfvpRoq5AQS4ItjLHzA1

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 payperbyte-merchant-screen-x402-pre-settlement-verification-afa0abd4 -d '<json body>'
```

Example prompt: Before you settle that x402 payment, screen the merchant — the domain is checkout.example.com, the payTo address is 0xABC123, and the requested price is 0.05 USDC — give me a signed ALLOW/WARN/BLOCK verdict.

## When to prefer this

Choose this endpoint when an AI agent is operating autonomously in an x402 payment flow and needs a pre-settlement trust signal before committing funds. It is specifically designed for the x402 protocol context, returns a machine-actionable signed verdict, and covers the unique (domain + payTo + price) triple that defines an x402 merchant storefront — making it more targeted than generic blockchain address lookup services.

## Known failure modes

- Unknown or unresolvable domain returns WARN or BLOCK with low-confidence signal
- Mismatched payTo address for a known domain triggers BLOCK
- Price outside expected range for a known merchant may trigger WARN
- Malformed input (invalid address format, missing fields) returns a 4xx error
- Network timeout or service unavailability returns no verdict — agent should treat as WARN and not proceed

## How this service works

Pre-settlement merchant screen: signed ALLOW/WARN/BLOCK on (domain, payTo, price) before you settle. Queries are logged (domain, payTo, price); screening is not covert — the merchant sees the probe. Full disclosure: https://x402.payperbyte.io/feeds

## Output

A cryptographically signed JSON verdict containing one of ALLOW, WARN, or BLOCK for the submitted (domain, payTo address, observed price) combination, along with supporting risk signals and metadata about why the verdict was reached.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "chain": {
   "enum": [
    "base"
   ],
   "type": "string",
   "default": "base"
  },
  "domain": {
   "type": "string",
   "description": "The merchant host the agent is about to pay."
  },
  "address": {
   "type": "string",
   "pattern": "^0x[0-9a-fA-F]{40}$",
   "description": "Optional — the payTo the agent observed."
  },
  "observed_price_atomic": {
   "type": "string",
   "pattern": "^[0-9]+$",
   "description": "Optional — atomic USDC price quoted to the agent. STRING (may exceed 2^53; a JSON number is rejected upstream)."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/payperbyte-merchant-screen-x402-pre-settlement-verification-afa0abd4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.payperbyte.io](https://www.zero.xyz/host/x402.payperbyte.io/llms.txt)