# x402 Wallet Balance Lookup

> x402 Wallet Balance Lookup is a paid API for AI agents from agentx402pay.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).

Returns native and optional ERC-20 token balances for an EVM wallet address across major chains (Base, Ethereum, Polygon, Arbitrum, Optimism)

## Facts

- Endpoint: GET https://agentx402pay.com/api/wallet-balance?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-wallet-balance-lookup-59a0f8ee
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_edzh2vbbWy_quQ-5QjwAU

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 x402-wallet-balance-lookup-59a0f8ee
```

Example prompt: What's the ETH balance of wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Ethereum, and also check how much USDC (contract 0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48) it holds?

## When to prefer this

Choose this endpoint when you need a simple, paid-per-call balance lookup for an EVM wallet without managing your own RPC infrastructure. Ideal for agents that need to verify wallet funding before transactions, monitor balances across chains, or enrich wallet data. Prefer this over self-hosted RPC calls when you want a managed, multi-chain abstraction at low cost. Use the sibling x402 Multi-Chain RPC endpoint if you need raw JSON-RPC flexibility beyond balance lookups.

## Known failure modes

- Invalid or malformed wallet address (non-0x format) returns an error
- Unsupported chain name returns an error — only base, ethereum, polygon, arbitrum, optimism are valid
- Invalid ERC-20 contract address returns an error or empty token balance
- Network/RPC timeout may cause transient failures
- Payment failure (insufficient USDC) blocks the request

## How this service works

Native and (optional) ERC-20 token balance for a wallet address across major EVM chains (base, ethereum, polygon, arbitrum, optimism)

## Output

Returns the native token balance (e.g. ETH, MATIC) for the specified wallet address on the requested chain, plus an optional ERC-20 token balance if a contract address is provided. Balances are returned as numeric values with token denominations.

## 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": {
      "chain": {
       "type": "string",
       "description": "Chain to query: base, ethereum, polygon, arbitrum, optimism (default base)"
      },
      "token": {
       "type": "string",
       "description": "Optional ERC-20 token contract address to also check"
      },
      "address": {
       "type": "string",
       "description": "EVM wallet address (0x...)"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-wallet-balance-lookup-59a0f8ee/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentx402pay.com](https://www.zero.xyz/host/agentx402pay.com/llms.txt)