# Base Mainnet ETH & USDC Balance Lookup

> Base Mainnet ETH & USDC Balance Lookup is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-12).

Returns ETH balance, USDC balance, transaction count, and an x402 affordability hint for a given Base mainnet address

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/base-balance?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-mainnet-eth-usdc-balance-lookup-34808620
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HgdToBZ8CWyD3I41JX8hI

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 base-mainnet-eth-usdc-balance-lookup-34808620 -d '<json body>'
```

Example prompt: What are the ETH and USDC balances for 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Base mainnet, and does it have enough to cover x402 micropayments?

## When to prefer this

Choose this endpoint when you specifically need on-chain Base mainnet (eip155:8453) ETH and USDC balances together with an x402 affordability hint in a single call. It is ideal for agents operating in the x402 payment ecosystem that need to verify wallet funding before initiating micropayments. Prefer it over generic blockchain explorers when you need a programmatic, structured JSON response including the x402_hint field.

## Known failure modes

- Invalid or malformed address returns a 400 error
- Non-checksummed address that is ambiguous may be rejected
- Network timeout or Base RPC node unavailability returns a 5xx error
- Address with zero balance returns valid response with zeroed fields
- Unsupported network addresses (non-Base) will not return correct results

## How this service works

Call when an agent needs Base mainnet ETH and USDC balances, tx_count, and a rough x402 affordability hint for one address. Send address as EIP-55 or all-lowercase 0x. Read-only eth_getBalance and USDC balanceOf on eip155:8453. No private key and no spend. Send JSON {"address":"0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"}. Exact $0.003 USDC on Base. Try unpaid POST /v1/sandbox/base-balance first.

## Output

Returns a JSON object containing the address's ETH balance in both wei and decimal, USDC balance in both atomic units and decimal, the total transaction count (nonce), and an x402_hint boolean or affordability signal indicating whether the wallet has sufficient funds to make x402 micropayments on Base.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "address": {
   "type": "string",
   "examples": [
    "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
   ],
   "description": "EVM address on Base mainnet (eip155:8453). Example: 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045. EIP-55 checksum or all one case. Returns eth_wei, eth, usdc_atomic, usdc, tx_count, and x402_hint. Read-only. No private key."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-mainnet-eth-usdc-balance-lookup-34808620/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)