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This quickstart guide helps you write a standalone index.js script that checks your USDC balance and sends a test transfer on the Starknet Sepolia. It’s designed for developers looking to quickly get hands-on with USDC on Starknet.

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Prerequisites

Before you begin, make sure you have:

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USDC contract address

Use the following contract address for USDC on the Starknet Sepolia Testnet: USDC contract: 0x0512feAc6339Ff7889822cb5aA2a86C848e9D392bB0E3E237C008674feeD8343

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Part 1: Set up your project

Follow these steps to install dependencies and set up your script environment.

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1.1. Initialize a project

Create a new directory and initialize it with npm: 
mkdir usdc-starknet-script
cd usdc-starknet-script
npm init -y
npm pkg set type=module

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1.2. Install required dependencies

Install starknet (version 8.x) and dotenv: 
npm install starknet@^8.9.0 dotenv

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1.3. Create your .env file

In the project root, create a .env file and add the following values:
Text
# Your Starknet account address (felt252 format with 0x prefix)
ACCOUNT_ADDRESS=0x<YOUR_ACCOUNT_ADDRESS>

# Your private key (felt252 format with 0x prefix)
PRIVATE_KEY=0x<YOUR_PRIVATE_KEY>

# The address you want to send USDC to (felt252 format with 0x prefix)
RECIPIENT_ADDRESS=0x<RECIPIENT_ADDRESS>
Important: On Starknet, you need both your account address and private key because Starknet uses account abstraction. Your private key alone doesn’t derive your account address.

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Part 2: Build your script

Create a file named index.js. You’ll build your script step-by-step in the following sections.

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2.1. Import libraries and define constants

In index.js, start by importing dependencies and setting up the chain and token configuration: 
import "dotenv/config";
import { Account, Contract, RpcProvider, uint256 } from "starknet";

const provider = new RpcProvider({
  nodeUrl:
    "https://starknet-sepolia.g.alchemy.com/starknet/version/rpc/v0_10/YOUR_API_KEY",
});

const USDC_ADDRESS =
  "0x053b40A647CEDfca6cA84f542A0fe36736031905A9639a7f19A3C1e66bFd5080";
const USDC_DECIMALS = 6;

const USDC_ABI = [
  {
    name: "balance_of",
    type: "function",
    inputs: [
      {
        name: "account",
        type: "core::starknet::contract_address::ContractAddress",
      },
    ],
    outputs: [{ name: "balance", type: "core::integer::u256" }],
    state_mutability: "view",
  },
  {
    name: "transfer",
    type: "function",
    inputs: [
      {
        name: "recipient",
        type: "core::starknet::contract_address::ContractAddress",
      },
      { name: "amount", type: "core::integer::u256" },
    ],
    outputs: [{ name: "success", type: "core::bool" }],
    state_mutability: "external",
  },
];
Replace YOUR_API_KEY with your Alchemy API key from alchemy.com/starknet
This ABI includes only the two methods needed for this script:
  • balanceOf(address) to check the token balance.
  • transfer(to, amount) to send USDC.
This makes the ABI compact and easier to understand. Using a minimal ABI:
  • Reduces complexity by excluding unrelated functions.
  • Speeds up onboarding for new developers.
  • Avoids unnecessary contract data that would be unused in this context.
Note: Starknet uses Cairo, so function names follow snake_case convention (for example, balance_of instead of balanceOf).

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2.2. Set up Starknet account and contract

Set up the Starknet account and contract instances: 
const account = new Account({
  provider,
  address: process.env.ACCOUNT_ADDRESS,
  signer: process.env.PRIVATE_KEY,
});

const usdcContract = new Contract({
  abi: USDC_ABI,
  address: USDC_ADDRESS,
  providerOrAccount: account,
});
Unlike Ethereum, Starknet uses account abstraction by default:
  • Every wallet is a smart contract (not an EOA).
  • You need both the account address AND private key.
  • The private key signs transactions, but the account contract validates them.
This enables features like:
  • Multi-signature wallets
  • Social recovery
  • Custom transaction validation logic
  • Gasless transactions (meta-transactions)

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2.3. Check balance and send USDC

Now add the logic to check your balance and send tokens: 
(async () => {
  try {
    const balanceResult = await usdcContract.balance_of(account.address);
    const balance = uint256.uint256ToBN(balanceResult.balance);
    const balanceFormatted = Number(balance) / 10 ** USDC_DECIMALS;

    console.log("Sender:", account.address);
    console.log("Recipient:", process.env.RECIPIENT_ADDRESS);
    console.log("USDC balance:", balanceFormatted.toFixed(2));

    const amount = 0.1;
    const amountU256 = uint256.bnToUint256(amount * 10 ** USDC_DECIMALS);

    const tx = await usdcContract.transfer(
      process.env.RECIPIENT_ADDRESS,
      amountU256,
    );

    await provider.waitForTransaction(tx.transaction_hash);

    console.log("Transfer successful!");
    console.log("Tx hash:", tx.transaction_hash);
    console.log(
      "Explorer:",
      `https://sepolia.voyager.online/tx/${tx.transaction_hash}`,
    );
  } catch (err) {
    console.error("Transfer failed:", err.message || err);
    process.exit(1);
  }
})();

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Part 3: Run your script

To run your script, use the following command: 
node index.js

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Sample output

If the script runs successfully, your terminal will print a transaction summary like this:
Text
Sender: 0x025c0197095dff110edc45fd171c498b167fbe1c803294d22483064b0207a465
Recipient: 0x043ccE75C31169455E07B19265024107B067700BB711DEeffecE32766d7bf5c7
USDC balance: 10.00
Transfer successful!
Tx hash: 0xabc123def456789...
Explorer: https://sepolia.voyager.online/tx/0xabc123def456789...
You can open the explorer link in your browser to view the transaction on Voyager.

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Additional notes

  • Testnet only: This guide runs on the Starknet Sepolia testnet. Tokens and transfers here are not real and hold no value.
  • Security best practices: Always store sensitive data like private keys in environment variables. Never hardcode or commit .env files to version control. Add .env to your .gitignore file.
  • Gas fees: Starknet requires STRK tokens for gas. Be sure to request testnet STRK from the faucet so your transactions can be processed.
  • Lightweight ABI: The ABI used here is minimal. It includes only the functions necessary for balance checks and transfers, which keeps the script lean.
  • V3 transactions: Starknet.js v8 uses V3 transactions by default, which include resource bounds for L1 gas, L2 gas, and L1 data gas.
  • Wallet compatibility: Braavos wallet is recommended for programmatic transactions. Argent accounts with guardians may require additional configuration.