# AUN Base Balance Checker

> AUN Base Balance Checker is a paid API for AI agents from a-upgradenet.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-23).

Fetches ETH and ERC-20 token balances for a given 0x address on the Base blockchain

## Facts

- Endpoint: POST https://a-upgradenet.com/x402/base-balance?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/aun-base-balance-checker-edf34eb6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_sahLOMMv1UB56PDc_aGCd

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 aun-base-balance-checker-edf34eb6 -d '<json body>'
```

Example prompt: What's the current USDC and ETH balance for the Base wallet address 0x1234abcd…efgh right now?

## When to prefer this

Use this endpoint when you need a fast, on-chain balance lookup specifically for addresses on the Base L2 network, particularly for USDC or other ERC-20 tokens. Prefer this over generic blockchain explorers when you need structured JSON output ready for downstream agent logic, and when you want to check up to 10 tokens in a single call without managing your own RPC node.

## Known failure modes

- Invalid or malformed 0x address returns an error response
- Non-existent ERC-20 contract address may return zero balance or error
- Exceeding the 10-token limit in the tokens array causes a validation error
- Network congestion on Base may cause timeouts
- Payment failure (x402 protocol) prevents the call from being processed

## How this service works

Base Wallet Balance: ETH and ERC-20 balances (USDC by default, up to 10 tokens) of any address on Base mainnet. $0.001 per call.

## Output

Returns a JSON object containing the wallet's ETH balance (in both ETH and wei), the block number at query time, the chain identifier ('base'), a status field, and an array of token objects each with address, symbol, decimals, raw balance, and human-readable balance.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "tokens": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 10,
   "description": "ERC-20 contract addresses. Defaults to Base USDC."
  },
  "address": {
   "type": "string",
   "description": "0x address on Base."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "eth": "0.0123",
  "chain": "base",
  "status": "completed",
  "tokens": [
   {
    "raw": "25500000",
    "symbol": "USDC",
    "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "balance": "25.5",
    "decimals": 6
   }
  ],
  "address": "0x…",
  "eth_wei": "12300000000000000",
  "block_number": "21000000"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aun-base-balance-checker-edf34eb6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from a-upgradenet.com](https://www.zero.xyz/host/a-upgradenet.com/llms.txt)