# PennyRail x402 Quote Inspector

> PennyRail x402 Quote Inspector is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-15).

Probes a public HTTP endpoint and decodes its HTTP 402 payment requirements into structured JSON, returning network, asset, amount, pay-to address, and challenge metadata.

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/bazaar/x402-quote
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-x402-quote-inspector-9466df35
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Lhrb1yoVkwpS6F-IEZ-N0

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 pennyrail-x402-quote-inspector-9466df35 -d '<json body>'
```

Example prompt: Check what payment this endpoint requires before I can call it — probe https://api.example.com/data using a POST with a JSON body and decode any x402 payment requirements like the network, asset, amount, and pay-to address.

## When to prefer this

Use this endpoint when you need to programmatically discover the payment requirements of an unknown HTTP API before attempting to pay and call it. It is specifically designed for the x402 payment protocol and decodes structured payment metadata that generic HTTP probing tools would not interpret. Prefer this over manual inspection when building agents that need to auto-discover and satisfy API payment requirements at runtime.

## Known failure modes

- Endpoint does not return a 402 response — no payment metadata available
- Target URL is unreachable or times out
- Endpoint returns 402 but with a non-standard or unrecognized payment scheme
- Malformed or missing x402 headers on the target endpoint
- Target endpoint requires authentication before returning 402 metadata

## How this service works

Probe a public HTTP endpoint without paying and decode its HTTP 402 payment requirements into clean JSON: status, network, asset, amount, pay-to and challenge metadata when exposed. Exact-match PennyRail gap-arbitrage route.

## Output

A JSON object containing the decoded HTTP 402 payment requirements of the probed endpoint, including: payment status, blockchain network, accepted asset (e.g. USDC), required amount, pay-to wallet address, and any challenge or nonce metadata exposed by the endpoint's x402 payment header.

## 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": {
     "type": "object",
     "description": "Input for x402 payment quote inspector.",
     "additionalProperties": true
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-x402-quote-inspector-9466df35/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pennyrail.vercel.app](https://www.zero.xyz/host/pennyrail.vercel.app/llms.txt)