USDC balance

Read the USDC balance of any address on Base, Polygon, Arbitrum, Optimism, Ethereum, Monad, Celo, Avalanche, Sei, or Arc. Send GET /api/usdc-balance with the required field address and pay $0.003 per call over x402 or MPP (there is no free tier). It returns a JSON object with address, usdc, raw, token and network.

Read-only on-chain call. The minimal single-token read for payment flows - for EVERY token a wallet holds in one call use wallet-balance.

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Parameters

Example request

curl -i "https://agent402.tools/api/usdc-balance?address=0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0&network=base"

Without payment this returns HTTP 402 Payment Required with the exact price for usdc-balance; any x402 v2 or MPP client pays it and retries.

Example response

{
  "address": "0x…",
  "usdc": "12.5",
  "raw": "12500000",
  "token": "USDC",
  "network": "base"
}

From an MCP client

catalog.call {
  "slug": "usdc-balance",
  "params": {
    "address": "0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0",
    "network": "base"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for usdc-balance; the stdio package pays it from a wallet or from an AGENT402_CREDITS_KEY issued earlier. Local install: npx -y agent402-mcp.

Errors and behavior

• address is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is canceled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• Cached: an identical request within 30s is answered from cache with X-Cache: hit.
• A POST with a JSON body to /api/usdc-balance is served as this GET, with the body as the input.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

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();
client.setSpendControls?.({ maxAmountPerPayment: "$0.003" }); // refuse any quote above this tool's price
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/usdc-balance?address=0xaBF4FAbd7c416fB67202E5f9002389Fc75e2a9D0&network=base");

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