# OP Mainnet Wallet Balance Checker

> OP Mainnet Wallet Balance Checker is a paid API for AI agents from onchaincheck.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).

Returns the native ETH balance plus up to 20 ERC-20 token balances for a given OP Mainnet wallet address, with symbols and decimals formatted for readability.

## Facts

- Endpoint: GET https://onchaincheck.dev/optimism/balances?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/op-mainnet-wallet-balance-checker-dd142e90
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_o08ri_RIOSE_Zhr9IUn0I

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 op-mainnet-wallet-balance-checker-dd142e90
```

Example prompt: What's the ETH balance and token balances for wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 on Optimism? Also check USDC (0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85) and OP (0x4200000000000000000000000000000000000042) while you're at it.

## When to prefer this

Choose this endpoint when you need live, real-time ETH and ERC-20 token balances specifically on Optimism (OP Mainnet) for a given wallet. It is ideal for portfolio checks, pre-transaction validations, DeFi integrations, and automated monitoring workflows targeting Optimism L2. Prefer alternatives (sibling endpoints) for Arbitrum One, Base, or Ethereum Mainnet balances.

## Known failure modes

- Invalid or malformed wallet address returns an error
- Invalid ERC-20 contract address in the tokens list causes a failure or is skipped
- More than 20 token addresses provided will be rejected due to schema constraints
- RPC or node connectivity issues may cause temporary failures
- Non-existent or zero-balance addresses return zero values, not errors

## How this service works

Native ETH balance of a OP Mainnet wallet plus the balances of up to 20 ERC-20 tokens you list, formatted with each token's symbol and decimals, read live from OP Mainnet.

## Output

A JSON object containing the wallet address, the chain name ('optimism'), the native ETH balance as a human-readable decimal string, and an array of token objects each containing the contract address, symbol, decimals, raw balance integer, and formatted decimal balance.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "address"
     ],
     "properties": {
      "tokens": {
       "type": "string",
       "pattern": "^(0x[0-9a-fA-F]{40})(,0x[0-9a-fA-F]{40}){0,19}$",
       "description": "Comma-separated ERC-20 contract addresses on OP Mainnet, up to 20"
      },
      "address": {
       "type": "string",
       "pattern": "^0x[0-9a-fA-F]{40}$",
       "description": "Wallet address on OP Mainnet"
      }
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "chain": "optimism",
  "tokens": [
   {
    "raw": "24433911",
    "token": "0x0b2C639c533813f4Aa9D7837CAf62653d097Ff85",
    "symbol": "USDC",
    "balance": "24.433911",
    "decimals": 6
   },
   {
    "raw": "1000000000000000000",
    "token": "0x4200000000000000000000000000000000000042",
    "symbol": "OP",
    "balance": "1",
    "decimals": 18
   }
  ],
  "address": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
  "nativeSymbol": "ETH",
  "nativeBalance": "0.181079591875347535"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/op-mainnet-wallet-balance-checker-dd142e90/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from onchaincheck.dev](https://www.zero.xyz/host/onchaincheck.dev/llms.txt)