Alchemy Hello World

Alchemy Hello World

Overview

Minimal working examples with the real Alchemy SDK: get ETH balance, fetch NFTs for a wallet, read ERC-20 token balances, and subscribe to pending transactions.

Prerequisites

• Completed alchemy-install-auth setup
• alchemy-sdk installed (npm install alchemy-sdk)
• Valid API key configured

Instructions

Step 1: Get ETH Balance

// src/hello-world/get-balance.ts
import { Alchemy, Network, Utils } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function getBalance(address: string) {
  const balanceWei = await alchemy.core.getBalance(address);
  const balanceEth = Utils.formatEther(balanceWei);
  console.log(`Balance of ${address}: ${balanceEth} ETH`);
  return balanceEth;
}

// Query Vitalik's address
getBalance('0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045').catch(console.error);

Step 2: Fetch NFTs for a Wallet

// src/hello-world/get-nfts.ts
import { Alchemy, Network } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function getNftsForOwner(owner: string) {
  const nfts = await alchemy.nft.getNftsForOwner(owner);
  console.log(`Total NFTs: ${nfts.totalCount}`);

  for (const nft of nfts.ownedNfts.slice(0, 5)) {
    console.log(`  ${nft.contract.name} — ${nft.name || nft.tokenId}`);
    console.log(`    Contract: ${nft.contract.address}`);
    console.log(`    Token ID: ${nft.tokenId}`);
    if (nft.image?.cachedUrl) {
      console.log(`    Image: ${nft.image.cachedUrl}`);
    }
  }

  return nfts;
}

getNftsForOwner('vitalik.eth').catch(console.error);

Step 3: Get ERC-20 Token Balances

// src/hello-world/get-tokens.ts
import { Alchemy, Network } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function getTokenBalances(address: string) {
  const balances = await alchemy.core.getTokenBalances(address);

  console.log(`Token balances for ${address}:`);
  for (const token of balances.tokenBalances.slice(0, 10)) {
    if (token.tokenBalance && token.tokenBalance !== '0x0') {
      // Get token metadata for human-readable names
      const metadata = await alchemy.core.getTokenMetadata(token.contractAddress);
      const balance = parseInt(token.tokenBalance, 16) / Math.pow(10, metadata.decimals || 18);
      console.log(`  ${metadata.symbol}: ${balance.toFixed(4)}`);
    }
  }
}

getTokenBalances('0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045').catch(console.error);

Step 4: Get Latest Block Info

// src/hello-world/get-block.ts
import { Alchemy, Network } from 'alchemy-sdk';

const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY,
  network: Network.ETH_MAINNET,
});

async function getLatestBlock() {
  const blockNumber = await alchemy.core.getBlockNumber();
  const block = await alchemy.core.getBlock(blockNumber);

  console.log(`Block #${blockNumber}`);
  console.log(`  Hash: ${block.hash}`);
  console.log(`  Timestamp: ${new Date(block.timestamp * 1000).toISOString()}`);
  console.log(`  Transactions: ${block.transactions.length}`);
  console.log(`  Gas Used: ${block.gasUsed.toString()}`);
}

getLatestBlock().catch(console.error);

Output

• ETH balance query with Wei → ETH conversion
• NFT enumeration with metadata and images
• ERC-20 token balances with symbol resolution
• Block data with timestamp and gas usage

Error Handling

Resources

• Alchemy SDK Reference
• Alchemy NFT API
• Alchemy Enhanced APIs

Next Steps

Proceed to alchemy-local-dev-loop for development workflow setup.