# PennyRail JSON Keys Extractor

> PennyRail JSON Keys Extractor is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-22).

Extracts and returns the keys from a JSON object via a paid micro-transaction endpoint

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/json.keys--json-keys?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-json-keys-extractor-9e96b2e2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WI8T76YYXiMycc0P4lQ-M

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-keys-extractor-9e96b2e2 -d '<json body>'
```

Example prompt: Can you extract and list all the top-level keys from this JSON object for me: {"name": "Alice", "age": 30, "role": "admin"}?

## When to prefer this

Use this endpoint when you need a quick, programmatic way to enumerate the keys of a JSON object without writing custom parsing logic, especially in agent pipelines where you want to inspect or validate the structure of an unknown JSON payload on the fly and are comfortable with micro-payment per call.

## Known failure modes

- Missing or malformed 'input' field returns a validation error
- Input is not a JSON object (e.g. array or primitive) may return unexpected results
- Payment not fulfilled results in HTTP 402 and the call is not processed
- Network timeout on the Vercel edge function

## How this service works

Machine-readable settlement service

## Output

A JSON object containing the extracted key names from the provided input object, returned as a machine-readable response with dynamic properties.

## 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-keys-extractor-9e96b2e2/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)