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Step 1. Generate the project

Open your terminal and run: 
npx capx-compose arbitrum-agent
The CLI will guide you through the setup. For now select:
  1. Web3 - Blockchain/DeFi Application (we’re building on-chain)
  2. EVM - Ethereum Virtual Machine (for Arbitrum and other L2s)
  3. Goat - Press space to select this AI agent plugin, then enter
  4. No for ESLint (optional for hackathons)
  5. Yes to automatically install dependencies
  6. Auto-detect for package manager
Wait about 3 minutes for the setup to complete. This automatically sets up a Next.js project with:
  • GOAT SDK configured for blockchain operations
  • EVM wallet integration auto-included
  • Vercel AI SDK for streaming GPT responses
  • Working examples you can extend immediately

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Step 2. Configure your environment

Now your project setup is done, navigate to your project & run the following command: 
cd arbitrum-agent
cp .env.example .env.local
Open .env.local and add your credentials: 
# OpenAI Configuration
OPENAI_API_KEY=sk-... # Get from platform.openai.com/api-keys

# Blockchain Configuration
GOAT_CHAIN=evm
WALLET_PRIVATE_KEY=0x... # Your test wallet private key (we'll create this next)
RPC_PROVIDER_URL=https://sepolia-rollup.arbitrum.io/rpc # Arbitrum testnet

# Optional RPCs (if you need better reliability)
NEXT_PUBLIC_INFURA_PROJECT_ID=... # From infura.io
NEXT_PUBLIC_ALCHEMY_API_KEY=... # From alchemy.com
Note: The default RPC suggests Base Sepolia, but we’re using Arbitrum Sepolia for this guide.

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Step 2.5. Create a test wallet

Since we need a wallet private key, let’s create one:

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Option 1: Using MetaMask (Easiest)

  1. Open MetaMask browser extension
  2. Click the account icon → Add Account or Wallet → Create a new account → Ethereum
  3. Name it “Hackathon Test” (so you remember it’s not your main)
  4. Click the three dots → Account details → Export Private Key
  5. Enter your password and copy the key
  6. Paste it in .env.local as WALLET_PRIVATE_KEY=0x…

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Option 2: Generate programmatically

node -e "const { Wallet } = require('ethers'); const w = Wallet.createRandom(); console.log('Address:', w.address); console.log('Private Key:', w.privateKey);"
Copy the private key to your .env.local.
Important: This is a test wallet. Never put real funds in it. Never use your main wallet for hackathon projects.

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Step 3. Configure for Arbitrum

The template defaults to Base. Let’s configure it for Arbitrum specifically. Find your wallet config file at src/utils/wallet-config.ts and update the chain import: 
import { createWalletClient, http } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import { arbitrumSepolia } from "viem/chains"; // Change this from baseSepolia
import { getOnChainTools } from "@goat-sdk/adapter-vercel-ai";
import { viem } from "@goat-sdk/wallet-viem";

// Update the wallet client configuration
const walletClient = createWalletClient({
  account: wallet.account,
  transport: http(rpcUrl),
  chain: arbitrumSepolia, // Update from baseSepolia
});

// Also update the network info
export function getWalletInfo(chain: ChainType) {
  return {
    network: 'Arbitrum Sepolia',
    explorer: 'https://sepolia.arbiscan.io'
  };
}

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Step 4. Get test ETH

You’ll need some testnet ETH for gas fees:
  1. Copy your wallet address (from MetaMask or log it from your code)
  2. Visit https://faucet.quicknode.com/arbitrum/sepolia
  3. Paste your address and claim
  4. You’ll receive 0.001 ETH, enough for plenty of transactions on Arbitrum

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Step 5. Test your app

Start the development server: 
npm run dev
Navigate to http://localhost:3000 and click on the “GOAT Example” card to open the agent interface. Make sure everything’s working. Try asking your agent: “What’s my ETH balance?” You should see your balance (0.001 ETH if the faucet just sent it) and your wallet address. If it shows 0 ETH, wait 30 seconds for the faucet transaction to confirm. Now let’s do something real, send a transaction: “Send 0.0001 ETH to 0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb9” Your agent will execute the transaction and give you a transaction hash with an Arbiscan link. Click it to verify on-chain - you’ll see the transaction confirmed in 2-3 seconds with a green checkmark, showing your wallet as the sender. Verifying Your Transaction Let’s make sure it worked:
  1. Click the explorer link in the response, or
  2. Visit https://sepolia.arbiscan.io
  3. Paste your transaction hash in the search box
  4. You should see:
  • Status: Success (green checkmark)
  • From: Your wallet address
  • To: The recipient address
  • Value: 0.0001 ETH
  • Block: Confirmed within 2-3 seconds