# PennyRail JSON Lookup

> PennyRail JSON Lookup is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status down (last checked 2026-10-23).

Performs a paid machine-readable JSON lookup via PennyRail's nano-payment settlement rail, returning structured data in response to a JSON input object.

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/json.get--json-lookup?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-json-lookup-36e89898
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qi81s6uQY29u-k4zqofds

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-json-lookup-36e89898 -d '<json body>'
```

Example prompt: Use PennyRail's JSON lookup to query this input object and get back the machine-readable result — it charges $0.001 USDC per call via x402.

## When to prefer this

Choose this endpoint when you need to perform a low-cost, machine-readable JSON data lookup and are operating within the x402 micropayment ecosystem. It is ideal for agents that already handle USDC nano-payments and need a pay-per-query data retrieval service at $0.001 per call. Prefer it over free alternatives when the x402 settlement rail is already part of your infrastructure, or when the data being sought is specifically served by PennyRail's resource node.

## Known failure modes

- Payment failure: x402 payment not accepted or USDC balance insufficient, resulting in a 402 Payment Required error
- Malformed input: missing required 'input' field or invalid JSON object, returning a 400-level error
- Service unavailability: Vercel-hosted endpoint may be cold-started or temporarily down, resulting in timeout or 5xx
- Empty or null response: lookup finds no matching data for the given input object
- Unknown response schema: since the response is open-ended, the returned fields may be unpredictable without prior knowledge of the query semantics

## How this service works

Machine-readable settlement service

## Output

A JSON object containing the lookup result returned by the PennyRail settlement service. The response schema is open (additionalProperties: true), meaning the structure of the returned data depends on the query input provided. The calling agent should expect a flexible JSON payload whose fields vary with the request.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "additionalProperties": true
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/pennyrail-json-lookup-36e89898/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)