# Penny Engine — Base Wallet Balance Checker

> Penny Engine — Base Wallet Balance Checker is a paid API for AI agents from penny-paid-batch-production.up.railway.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-23).

Returns the ETH and USDC balances, address, network, and block number for a Base-chain wallet, paid via x402 micropayment.

## Facts

- Endpoint: GET https://penny-paid-batch-production.up.railway.app/api/base-wallet?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/penny-engine-base-wallet-balance-checker-63bbddff
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XDjLFfigA-AJwVi02kknb

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 penny-engine-base-wallet-balance-checker-63bbddff
```

Example prompt: What are the current ETH and USDC balances for the Base wallet at 0x72ded73b99cffedfc83f5fa74640cdbd1e642ba9?

## When to prefer this

Choose this endpoint when you need a fast, on-chain balance snapshot for an Ethereum-compatible wallet on the Base L2 network, especially in agent pipelines where micropayment-gated access (x402) is already supported and cost-per-call must stay near zero ($0.001 USDC). Prefer this over manual RPC calls when you want a structured, ready-to-parse JSON response rather than raw hex values.

## Known failure modes

- Invalid or malformed wallet address returns an error or empty balances
- Network unavailability on Base RPC causes lookup failure
- Micropayment (x402) not fulfilled results in 402 Payment Required response
- Rate limiting if too many requests are sent in quick succession

## How this service works

Machine-to-machine result validation via x402. One structured call, deterministic PASS or FAIL and SHA-256 fingerprint, $0.001 USDC on Base.

## Output

A JSON object containing the wallet's ETH balance (18 decimal precision), USDC balance (6 decimal precision), the queried address, the network identifier (eip155:8453 for Base), the block number at query time, and a checkedAt timestamp.

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "eth": {
   "balance": "0.000000000000000000",
   "decimals": 18
  },
  "usdc": {
   "balance": "0.000000",
   "decimals": 6
  },
  "address": "0x72ded73b99cffedfc83f5fa74640cdbd1e642ba9",
  "network": "eip155:8453",
  "checkedAt": "example",
  "blockNumber": 0
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/penny-engine-base-wallet-balance-checker-63bbddff/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from penny-paid-batch-production.up.railway.app](https://www.zero.xyz/host/penny-paid-batch-production.up.railway.app/llms.txt)