# Base Mainnet Wallet Balance Checker

> Base Mainnet Wallet Balance Checker is a paid API for AI agents from x402-seller.onrender.com, paid per call via x402, $0.012/call, status unknown (last checked 2026-09-15).

Returns the live ETH (and optionally ERC20 token) balance for a given wallet address on Base mainnet, sourced from Base's official public RPC.

## Facts

- Endpoint: GET https://x402-seller.onrender.com/chain/balance
- Price: $0.012/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-mainnet-wallet-balance-checker-693b5e66
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0pY-mWqzGOz9-sNM0gbFH

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-wallet-balance-checker-693b5e66
```

Example prompt: What's the current ETH balance on Base mainnet for wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045, and can you also check its USDC balance using the token contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913?

## When to prefer this

Use this endpoint when you need a real-time, on-chain wallet balance specifically on Base mainnet — including both native ETH and any ERC20 token. Prefer it over general-purpose blockchain explorers when you need a simple, paid, low-latency lookup with a clean JSON response and no API key setup beyond x402 payment.

## Known failure modes

- Invalid or malformed wallet address returns an error
- Invalid ERC20 token contract address causes token balance lookup to fail
- RPC node unavailability returns a 5xx error
- Rate limiting or payment failure returns a 402 or 429 response
- Address with zero balance returns 0 rather than an error

## How this service works

Check a wallet's live balance on Base mainnet: native ETH (e.g. to confirm it has enough for gas) plus an optional ERC20 token balance (e.g. USDC) when a token contract address is supplied. Sourced from Base's official public RPC.

## Output

A JSON object containing the wallet address, network identifier ('base'), the native ETH balance as a number, an optional token balance object (if a token contract address was provided), and the RPC source string.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "token": {
       "type": "string",
       "description": "Optional ERC20 token contract address to also check"
      },
      "address": {
       "type": "string",
       "description": "Wallet address (0x...)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "token": {
       "type": [
        "object",
        "null"
       ]
      },
      "source": {
       "type": "string"
      },
      "address": {
       "type": "string"
      },
      "network": {
       "type": "string"
      },
      "ethBalance": {
       "type": "number"
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-mainnet-wallet-balance-checker-693b5e66/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-seller.onrender.com](https://www.zero.xyz/host/x402-seller.onrender.com/llms.txt)