Alchemy Install & Auth

Overview

Install the alchemy-sdk npm package and configure API authentication. Alchemy provides blockchain infrastructure (RPC nodes, Enhanced APIs, NFT APIs, webhooks) across Ethereum, Polygon, Arbitrum, Optimism, Base, and Solana.

Prerequisites

• Node.js 18+ (or Python 3.10+ for alchemy-sdk Python)
• Free Alchemy account at alchemy.com
• API key from Alchemy Dashboard

Instructions

Step 1: Install the Alchemy SDK

bash
# JavaScript/TypeScript (official SDK)
npm install alchemy-sdk

# Python (community SDK)
pip install alchemy-sdk

Step 2: Create an Alchemy App

1. Go to dashboard.alchemy.com
2. Click "Create new app"
3. Select chain: Ethereum, Polygon, Arbitrum, Optimism, Base, or Solana
4. Select network: Mainnet, Sepolia (testnet), or Mumbai
5. Copy the API key

Step 3: Configure Environment

bash
# Set environment variable
export ALCHEMY_API_KEY="your-api-key-here"

# Or create .env file
cat > .env << 'EOF'
ALCHEMY_API_KEY=your-api-key-here
ALCHEMY_NETWORK=ETH_MAINNET
EOF

echo ".env" >> .gitignore

Step 4: Initialize and Verify

typescript
// src/alchemy-client.ts
import { Alchemy, Network } from 'alchemy-sdk';

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

// Verify connection
async function verifyConnection() {
  const blockNumber = await alchemy.core.getBlockNumber();
  console.log(`Connected! Latest block: ${blockNumber}`);
  return blockNumber;
}

verifyConnection().catch(console.error);

Step 5: Multi-Chain Configuration

typescript
// src/config/chains.ts
import { Alchemy, Network } from 'alchemy-sdk';

// Create clients for multiple chains
const chains = {
  ethereum: new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: Network.ETH_MAINNET }),
  polygon: new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: Network.MATIC_MAINNET }),
  arbitrum: new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: Network.ARB_MAINNET }),
  optimism: new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: Network.OPT_MAINNET }),
  base: new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: Network.BASE_MAINNET }),
};

export default chains;

Supported Networks

| Chain | Network Enum | Mainnet | Testnet | |-------|-------------|---------|---------| | Ethereum | ETH_MAINNET | Yes | Sepolia | | Polygon | MATIC_MAINNET | Yes | Amoy | | Arbitrum | ARB_MAINNET | Yes | Sepolia | | Optimism | OPT_MAINNET | Yes | Sepolia | | Base | BASE_MAINNET | Yes | Sepolia | | Solana | SOL_MAINNET | Yes | Devnet |

Output

• alchemy-sdk installed in node_modules
• API key configured in environment
• Verified connection with latest block number
• Multi-chain client configuration ready

Error Handling

| Error | Cause | Solution | |-------|-------|----------| | Must provide apiKey | Missing env var | Set ALCHEMY_API_KEY in environment | | 401 Unauthorized | Invalid API key | Verify key in Alchemy Dashboard | | 429 Rate Limit | Free tier exceeded | Upgrade plan or reduce request rate | | ECONNREFUSED | Network blocked | Ensure HTTPS to .g.alchemy.com allowed |

Resources

• Alchemy Docs
• Alchemy SDK GitHub
• Alchemy Dashboard

Next Steps

Proceed to alchemy-hello-world for your first blockchain query.