Wallet balance (native + ERC-20)

Look up the native coin balance (ETH/MATIC) plus every ERC-20 holding for a wallet address on Ethereum, Base, Polygon, Arbitrum, or Optimism. Returns clean decimal balances (already scaled by token decimals) plus symbol and contract - ready to display in a UI or feed into a portfolio tool.

Input

Example output

{
  "address": "0xabf4fabd7c416fb67202e5f9002389fc75e2a9d0",
  "network": "base",
  "native": {
    "symbol": "ETH",
    "balance": "0.001234",
    "raw": "1234000000000000"
  },
  "tokens": [
    {
      "contract": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
      "symbol": "USDC",
      "decimals": 6,
      "balance": "100",
      "raw": "100000000"
    }
  ]
}

Try it - see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/wallet-balance \
  -H "Content-Type: application/json" \
  -d '{"address":"0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0","network":"base"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/wallet-balance", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "address": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "network": "base"
  }),
});

Part of these workflows

This tool is one step in 2 curated multi-tool workflows - agents can fetch the whole sequence as an MCP prompt or call https://agent402.tools/api/skill-packs/{slug}/prompt.

• NFT portfolio - NFT + wallet snapshot: NFT holdings, native balance, and ETH price for a given address in one call.
• Wallet audit - Full wallet activity review: balance, recent transactions, and token metadata for a given address.

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