# PennyRail JSON Path Lister

> PennyRail JSON Path Lister is a paid API for AI agents from pennyrail.vercel.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Extracts and lists all JSON paths (keys) present in a given JSON object

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/json.keys--list-json-paths
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/pennyrail-json-path-lister-0442ac75
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_gPicBL6x378MF04mX7esS

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-path-lister-0442ac75 -d '<json body>'
```

Example prompt: Can you list all the JSON paths in this object for me: {"user":{"id":123,"address":{"city":"Austin","zip":"78701"}},"active":true}?

## When to prefer this

Choose this endpoint when you need a quick, paid micro-service call to enumerate all JSON paths in an object without writing custom traversal code. Useful for schema discovery, debugging unknown payloads, or preparing for field mapping tasks. Prefer this over hand-rolled solutions when working inside an agentic workflow that already handles x402 micropayments.

## Known failure modes

- Missing or malformed 'input' field returns an error
- Non-object input types (arrays, primitives at root) may not be supported
- Very deeply nested or extremely large objects may cause timeout or truncation
- Payment failure via x402 protocol blocks the request with a 402 response

## How this service works

Machine-readable settlement service

## Output

An object containing a list of all JSON paths (dot-notation or similar key paths) found within the input JSON object, covering all nested properties and levels of the structure.

## 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-path-lister-0442ac75/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)