# PennyRail Block Number Lookup

> PennyRail Block Number Lookup 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).

Returns the current block number for a specified nano/chain via a paid settlement endpoint

## Facts

- Endpoint: POST https://pennyrail.vercel.app/api/p/nano/chain.block-number--block-number
- 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-block-number-lookup-743e298f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_F2dhaIVbPJr2X7Nk52IFw

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-block-number-lookup-743e298f -d '<json body>'
```

Example prompt: What is the current block number on the nano chain right now? Use the PennyRail settlement service to fetch it.

## When to prefer this

Use this endpoint when you need programmatic, machine-readable block number lookups for a nano chain and are operating in an x402 micropayment-enabled agent environment. It is well-suited for AI agents that can automatically handle sub-cent USDC payments per call. Prefer this over free alternatives when reliability and machine-readable settlement semantics are required.

## Known failure modes

- Payment not included or insufficient USDC — 402 response requiring x402 payment header
- Malformed input object — 400 bad request if required fields are missing or invalid
- Chain not found or unsupported chain identifier — may return empty or error response
- Service unavailability on Vercel — 503 or timeout
- Rate limiting if too many requests are made in quick succession

## How this service works

Machine-readable settlement service

## Output

Returns the current block number for the queried chain, along with any additional chain block metadata provided by the PennyRail settlement node.

## 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-block-number-lookup-743e298f/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)