Agent skill

alchemy-hello-world

Create a minimal Alchemy Web3 example: get ETH balance, fetch NFTs, read token balances. Use when starting blockchain development, testing Alchemy setup, or learning basic blockchain query patterns. Trigger: "alchemy hello world", "alchemy example", "alchemy quick start", "get ETH balance", "fetch NFTs alchemy".

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Forks 241

Install this agent skill to your Project

npx add-skill https://github.com/jeremylongshore/claude-code-plugins-plus-skills/tree/main/plugins/saas-packs/alchemy-pack/skills/alchemy-hello-world

SKILL.md

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

typescript
// 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

typescript
// 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

typescript
// 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

typescript
// 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

Error Cause Solution
Invalid address Malformed Ethereum address Use checksummed 0x-prefixed address
429 Too Many Requests Rate limit exceeded Add delay between calls or upgrade plan
ENS name not found ENS not resolving Verify ENS name exists on mainnet
Timeout Slow node response Increase timeout in SDK config

Resources

Next Steps

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

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