Alchemy Cost Tuning

Overview

Alchemy pricing is based on Compute Units (CU). Different API methods have different CU costs. Optimize by caching, batching, choosing cheaper methods, and right-sizing your plan.

Plan Comparison

CU Cost Reference (Top Methods)

Instructions

Step 1: CU Usage Monitor

// src/cost/cu-monitor.ts
const CU_COSTS: Record<string, number> = {
  'eth_blockNumber': 10, 'eth_getBalance': 19, 'eth_call': 26,
  'getTokenBalances': 50, 'getNftsForOwner': 50, 'getTokenMetadata': 50,
  'getAssetTransfers': 150, 'getNftMetadataBatch': 50,
};

class CuMonitor {
  private usage: Array<{ method: string; cu: number; timestamp: number }> = [];

  record(method: string): void {
    this.usage.push({ method, cu: CU_COSTS[method] || 26, timestamp: Date.now() });
  }

  getHourlyReport(): { totalCu: number; byMethod: Record<string, number> } {
    const cutoff = Date.now() - 3600000;
    const recent = this.usage.filter(u => u.timestamp > cutoff);
    const byMethod: Record<string, number> = {};
    let totalCu = 0;

    for (const u of recent) {
      byMethod[u.method] = (byMethod[u.method] || 0) + u.cu;
      totalCu += u.cu;
    }

    return { totalCu, byMethod };
  }

  getMonthlyProjection(): { projectedMonthly: number; planRecommendation: string } {
    const hourly = this.getHourlyReport();
    const projectedMonthly = hourly.totalCu * 24 * 30;

    let recommendation = 'Free';
    if (projectedMonthly > 300_000_000) recommendation = 'Growth';
    if (projectedMonthly > 1_200_000_000

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

                

                  
                    
                  
                  
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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

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

# Python (community SDK)
pip install alchemy-sdk

Step 2: Create an Alchemy App

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

Step 3: Configure Environment

# 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

// 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

// 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
AR
                
              

                

                  
                    
                  
                  
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Alchemy Local Dev Loop
Overview
Local Web3 development workflow using Alchemy as the RPC provider with Hardhat for local testing, Sepolia testnet for staging, and hot-reload for rapid iteration.
Prerequisites

Completed alchemy-install-auth setup
Node.js 18+
Alchemy API key with Sepolia testnet app

Instructions
Step 1: Initialize Hardhat Project with Alchemy

mkdir web3-project && cd web3-project
npm init -y
npm install --save-dev hardhat @nomicfoundation/hardhat-toolbox
npm install alchemy-sdk dotenv
npx hardhat init  # Select TypeScript project

Step 2: Configure Hardhat with Alchemy RPC

// hardhat.config.ts
import { HardhatUserConfig } from 'hardhat/config';
import '@nomicfoundation/hardhat-toolbox';
import 'dotenv/config';

const config: HardhatUserConfig = {
  solidity: '0.8.24',
  networks: {
    hardhat: {
      forking: {
        url: `https://eth-mainnet.g.alchemy.com/v2/${process.env.ALCHEMY_API_KEY}`,
        blockNumber: 19000000,  // Pin block for reproducible tests
      },
    },
    sepolia: {
      url: `https://eth-sepolia.g.alchemy.com/v2/${process.env.ALCHEMY_API_KEY}`,
      accounts: process.env.DEPLOYER_PRIVATE_KEY ? [process.env.DEPLOYER_PRIVATE_KEY] : [],
    },
  },
};

export default config;

Step 3: Alchemy-Powered Test Helper

// test/helpers/alchemy-helper.ts
import { Alchemy, Network } from 'alchemy-sdk';

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

export async function getTestnetBalance(address: string): Promise<string> {
  const balance = await alchemy.core.getBalance(address);
  return (parseInt(balance.toString()) / 1e18).toFixed(4);
}

export async function waitForTransaction(txHash: string): Promise<any> {
  return alchemy.core.waitForTransaction(txHash, 1, 60000);
}

export { alchemy };

Step 4: Development Scripts

{
  "scripts": {
    "dev": "npx hardhat node --fork https://eth-mainnet.g.alchemy.com/v2/${ALCHEMY_API_KEY}",
    "test": "npx hardhat test",
    "test:watch": "npx hardhat test --watch",
    "deploy:sepolia": "npx hardhat run scripts/deploy.ts --network sepolia",
    "verify": "npx hardhat verify --network sepolia"
  }
}

Step 5: Mainnet Fork Testing

// test/fork-test.ts
import { expect } from 'chai';
import { ethers } from 'hardhat';

describe('Mainnet Fork Tests', () => {
  it('should read USDC balance on forked mainnet', async () => {
    const USDC = '0xA0b86991c6218b36c1d19D4a2

                

              

                

                  
                    
                  
                  
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Alchemy Performance Tuning
Performance Targets

Operation
Target Latency
CU Cost


getBlockNumber
< 50ms
10


getBalance
< 100ms
19


getTokenBalances
< 200ms
50


getNftsForOwner
< 300ms
50


getAssetTransfers
< 500ms
150


Multi-chain portfolio
< 2s
~400


Instructions
Step 1: Response Caching with TTL

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

class BlockchainCache {
  private store = new Map<string, { data: any; expiry: number }>();

  // Different TTLs for different data freshness needs
  private TTL: Record<string, number> = {
    blockNumber: 12000,     // 12s (~1 block)
    balance: 30000,         // 30s
    tokenBalances: 60000,   // 60s
    nftOwnership: 300000,   // 5 min (NFTs transfer less frequently)
    contractMetadata: 3600000, // 1 hour (rarely changes)
    tokenMetadata: 86400000,   // 24 hours (almost never changes)
  };

  async cached<T>(category: string, key: string, fetcher: () => Promise<T>): Promise<T> {
    const cacheKey = `${category}:${key}`;
    const entry = this.store.get(cacheKey);
    if (entry && entry.expiry > Date.now()) return entry.data;

    const data = await fetcher();
    this.store.set(cacheKey, { data, expiry: Date.now() + (this.TTL[category] || 30000) });
    return data;
  }

  invalidate(category: string): void {
    for (const key of this.store.keys()) {
      if (key.startsWith(`${category}:`)) this.store.delete(key);
    }
  }
}

const cache = new BlockchainCache();
export { cache };

Step 2: Parallel Multi-Chain Fetching

// src/performance/parallel-fetch.ts
import { Alchemy, Network } from 'alchemy-sdk';
import { cache } from './cache';

const CHAINS = [
  { name: 'ethereum', network: Network.ETH_MAINNET },
  { name: 'polygon', network: Network.MATIC_MAINNET },
  { name: 'arbitrum', network: Network.ARB_MAINNET },
  { name: 'base', network: Network.BASE_MAINNET },
];

async function multiChainBalance(address: string) {
  const results = await Promise.allSettled(
    CHAINS.map(chain =>
      cache.cached('balance', `${chain.name}:${address}`, async () => {
        const client = new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: chain.network });
        const bal = await client.core.getBalance(address);
        return { chain: chain.name, balance: (parseInt(bal.toString()) / 1e18).toFixed(6) };
      })
    )
  );

  return results
    .filter((r): r is Promi

                

              

                

                  
                    
                  
                  
                  alchemy-prod-checklist
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Alchemy Production Checklist
Pre-Launch Checklist
API & Infrastructure

[ ] API key restricted to production domains in Alchemy Dashboard
[ ] Separate Alchemy apps for dev/staging/prod environments
[ ] Rate limit headroom verified (< 70% of CU/sec budget)
[ ] Retry logic with exponential backoff implemented
[ ] Error monitoring configured (Sentry, Datadog, etc.)
[ ] Webhook endpoints HTTPS-only with signature verification

Security

[ ] API key NOT in frontend code — proxied through backend
[ ] Private keys in secret manager (not env files)
[ ] All user-supplied addresses validated and checksummed
[ ] No console.log of sensitive data in production builds
[ ] npm audit clean — no critical vulnerabilities

Smart Contracts (if applicable)

[ ] Contracts audited by reputable firm
[ ] Deployed and verified on Etherscan/Polygonscan
[ ] Admin keys secured in multi-sig wallet
[ ] Emergency pause function tested

Performance

[ ] Response caching for frequently-queried data (balances, metadata)
[ ] Connection pooling for provider instances
[ ] Batch requests where possible (NFT metadata, balances)
[ ] WebSocket reconnection logic for real-time subscriptions

Validation Script

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

async function checkReadiness(): Promise<void> {
  const checks: Array<{ name: string; pass: boolean; detail: string }> = [];

  // 1. API connectivity
  const alchemy = new Alchemy({ apiKey: process.env.ALCHEMY_API_KEY, network: Network.ETH_MAINNET });
  try {
    const block = await alchemy.core.getBlockNumber();
    checks.push({ name: 'API Connectivity', pass: true, detail: `Block ${block}` });
  } catch (err: any) {
    checks.push({ name: 'API Connectivity', pass: false, detail: err.message });
  }

  // 2. Enhanced API
  try {
    await alchemy.core.getTokenBalances('0x0000000000000000000000000000000000000000');
    checks.push({ name: 'Enhanced API', pass: true, detail: 'getTokenBalances works' });
  } catch { checks.push({ name: 'Enhanced API', pass: false, detail: 'Enhanced API unavailable' }); }

  // 3. NFT API
  try {
    await alchemy.nft.getContractMetadata('0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D');
    checks.push({ name: 'NFT API', pass: true, detail: 'getContractMetadata works' });
  } catch { checks.push({ name: 'NFT API', pass: false, detail: 'NFT API unavailable' }); }

  // 4. API key not in build output
  const fs = await import('fs');
  const buildDir = './dist';
  if (fs.existsSync(buildDir)) {
    const content = fs.readdirSync(buildDir, { 

                

              

                

                  
                    
                  
                  
                  alchemy-rate-limits
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Alchemy Rate Limits
Overview
Alchemy uses Compute Units (CU) to measure API usage. Different methods cost different CU amounts. Rate limits are per-second, and exceeding them returns 429 errors.
Compute Unit Costs

Method
CU Cost
Category


eth_blockNumber
10
Core


eth_getBalance
19
Core


eth_call
26
Core


eth_getTransactionReceipt
15
Core


getTokenBalances
50
Enhanced


getTokenMetadata
50
Enhanced


getAssetTransfers
150
Enhanced


getNftsForOwner
50
NFT


getNftMetadataBatch
50
NFT


getContractMetadata
50
NFT


Plan Limits

Plan
CU/sec
Monthly CU
Price


Free
330
300M
$0


Growth
660
1.2B
$49/mo


Scale
Custom
Custom
Custom


Instructions
Step 1: CU-Aware Request Throttler

// src/alchemy/throttler.ts
import Bottleneck from 'bottleneck';

const CU_COSTS: Record<string, number> = {
  'eth_blockNumber': 10,
  'eth_getBalance': 19,
  'eth_call': 26,
  'getTokenBalances': 50,
  'getAssetTransfers': 150,
  'getNftsForOwner': 50,
};

// Free tier: 330 CU/sec = ~16 getBalance calls/sec
const limiter = new Bottleneck({
  reservoir: 330,                    // CU budget per interval
  reservoirRefreshInterval: 1000,    // Refresh every second
  reservoirRefreshAmount: 330,       // Reset to max CU/sec
  maxConcurrent: 10,                 // Max parallel requests
  minTime: 50,                       // Min 50ms between requests
});

limiter.on('depleted', () => {
  console.warn('CU budget depleted — queueing requests');
});

async function throttledAlchemyCall<T>(
  method: string,
  operation: () => Promise<T>,
): Promise<T> {
  const cost = CU_COSTS[method] || 26; // Default to eth_call cost
  return limiter.schedule({ weight: cost }, operation);
}

export { throttledAlchemyCall, limiter };

Step 2: Batch Optimizer

// src/alchemy/batch-optimizer.ts
import { Alchemy } from 'alchemy-sdk';

// Instead of N individual calls, batch when possible
async function batchGetBalances(
  alchemy: Alchemy,
  addresses: stri

                

              

                

                  
                    
                  
                  
                  alchemy-reference-architecture
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Alchemy Reference Architecture
System Architecture

┌─────────────────────────────────────────────────────────┐
│                     Frontend (React/Next.js)              │
│  - Wallet connection (MetaMask, WalletConnect)           │
│  - Portfolio dashboard                                    │
│  - NFT gallery                                           │
│  - Transaction history                                    │
└────────────────────────┬────────────────────────────────┘
                         │ HTTPS (no API key exposed)
┌────────────────────────▼────────────────────────────────┐
│                     API Layer (Next.js/Express)           │
│  - /api/balance/:address                                 │
│  - /api/nfts/:owner                                      │
│  - /api/tokens/:address                                  │
│  - /api/transactions/:address                            │
│  - /webhooks/alchemy          (webhook receiver)         │
└───────┬──────────┬──────────┬───────────────────────────┘
        │          │          │
   ┌────▼───┐ ┌───▼────┐ ┌──▼──────┐
   │Alchemy │ │Alchemy │ │Alchemy  │
   │Core API│ │NFT API │ │Notify   │
   │(RPC)   │ │        │ │(Webhooks│
   └────────┘ └────────┘ └─────────┘
   ETH/Polygon/ARB/OP/Base

Project Structure

web3-dapp/
├── src/
│   ├── alchemy/
│   │   ├── client-factory.ts    # Multi-chain Alchemy client factory
│   │   ├── cache.ts             # Response caching with TTL
│   │   ├── throttler.ts         # CU-aware rate limiter
│   │   └── errors.ts            # Error classification
│   ├── portfolio/
│   │   ├── fetcher.ts           # Wallet portfolio aggregator
│   │   ├── transactions.ts      # Transaction history analyzer
│   │   └── multi-chain.ts       # Cross-chain balance aggregator
│   ├── nft/
│   │   ├── collection.ts        # NFT collection explorer
│   │   ├── batch-metadata.ts    # Batch metadata fetcher
│   │   └── verify-ownership.ts  # NFT ownership verification
│   ├── contracts/
│   │   ├── read-contract.ts     # Smart contract read operations
│   │   └── abis/                # Contract ABI files
│   ├── webhooks/
│   │   ├── handler.ts           # Webhook endpoint
│   │   ├── verify.ts            # HMAC signature verification
│   │   └── event-router.ts      # Event type routing
│   ├── security/
│   │   ├── validators.ts        # Input validation (addresses, blocks)
│   │   └── proxy.ts             # API key proxy for frontend
│   └── api/                     # API route handlers
├── tests/
│   ├── unit/                    # Unit tests (mocked Alchemy)
│   ├── fork/                    # Mainnet fork tests (Hardhat)
│   └── integration/             # Sepolia integration tests
├── contracts/                   # Solidity contracts (if applicable)
├── hardhat.config.ts            # Hardhat + Alchemy fork config
└── package.json

Key Design Decisions

Decision

                
              

                

                  
                    
                  
                  
                  alchemy-sdk-patterns
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'Apply production-ready Alchemy SDK patterns for Web3 applications.
                  

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Alchemy SDK Patterns
Overview
Production patterns for the alchemy-sdk package: singleton clients, multi-chain factories, response caching, and type-safe contract wrappers.
Instructions
Step 1: Multi-Chain Client Factory

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

type ChainName = 'ethereum' | 'polygon' | 'arbitrum' | 'optimism' | 'base';

const NETWORK_MAP: Record<ChainName, Network> = {
  ethereum: Network.ETH_MAINNET,
  polygon: Network.MATIC_MAINNET,
  arbitrum: Network.ARB_MAINNET,
  optimism: Network.OPT_MAINNET,
  base: Network.BASE_MAINNET,
};

class AlchemyClientFactory {
  private static clients = new Map<string, Alchemy>();

  static getClient(chain: ChainName): Alchemy {
    if (!this.clients.has(chain)) {
      this.clients.set(chain, new Alchemy({
        apiKey: process.env.ALCHEMY_API_KEY,
        network: NETWORK_MAP[chain],
        maxRetries: 3,
      }));
    }
    return this.clients.get(chain)!;
  }

  static getAllClients(): Map<ChainName, Alchemy> {
    for (const chain of Object.keys(NETWORK_MAP) as ChainName[]) {
      this.getClient(chain);
    }
    return this.clients as Map<ChainName, Alchemy>;
  }
}

export { AlchemyClientFactory, ChainName };

Step 2: Response Caching Layer

// src/alchemy/cache.ts
interface CacheEntry<T> { data: T; expiresAt: number; }

class AlchemyCache {
  private cache = new Map<string, CacheEntry<any>>();
  private defaultTtlMs: number;

  constructor(defaultTtlMs: number = 30000) { // 30s default
    this.defaultTtlMs = defaultTtlMs;
  }

  async getOrFetch<T>(key: string, fetcher: () => Promise<T>, ttlMs?: number): Promise<T> {
    const cached = this.cache.get(key);
    if (cached && cached.expiresAt > Date.now()) return cached.data;

    const data = await fetcher();
    this.cache.set(key, { data, expiresAt: Date.now() + (ttlMs || this.defaultTtlMs) });
    return data;
  }

  invalidate(keyPrefix: string): void {
    for (const key of this.cache.keys()) {
      if (key.startsWith(keyPrefix)) this.cache.delete(key);
    }
  }
}

// Usage with Alchemy
const cache = new AlchemyCache();

async function getCachedBalance(alchemy: Alchemy, address: string): Promise<string> {
  return cache.getOrFetch(
    `balance:${address}`,
    async () => {
      const balance = await alchemy.core.getBalance(address);
      return (parseInt(balance.toString()) / 1e18).toFixed(6);
    },
    15000 // 15s cache for balances
  );
}

export { AlchemyCache, getCachedBalance };

Step 3: Typed NFT Query Builder

// src/alchemy/nft-query.ts
import { Alchemy, NftOrdering } from 'alchemy-sdk';

class NftQueryBuilder {
  private alchemy: Alchemy

                

              

                

                  
                    
                  
                  
                  alchemy-security-basics
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Alchemy Security Basics
Overview
Web3 security practices for Alchemy-powered applications: API key protection, private key management, input validation, and smart contract interaction safety.
Security Checklist

Category
Requirement
Priority


API keys
Never expose in client-side code
Critical


Private keys
Use environment vars or secret manager
Critical


Addresses
Validate and checksum all inputs
High


RPC calls
Never pass user input directly to RPC
High


Webhooks
Verify HMAC signatures
High


Dependencies
Audit npm packages for supply chain
Medium


Instructions
Step 1: API Key Protection

// WRONG — API key in frontend code
// const alchemy = new Alchemy({ apiKey: 'demo123' }); // NEVER DO THIS

// RIGHT — API key in backend proxy
// src/api/proxy.ts
import express from 'express';
import { Alchemy, Network } from 'alchemy-sdk';

const app = express();
const alchemy = new Alchemy({
  apiKey: process.env.ALCHEMY_API_KEY, // Server-side only
  network: Network.ETH_MAINNET,
});

// Proxy endpoint — frontend calls this instead of Alchemy directly
app.get('/api/balance/:address', async (req, res) => {
  const { address } = req.params;
  if (!/^0x[a-fA-F0-9]{40}$/.test(address)) {
    return res.status(400).json({ error: 'Invalid address format' });
  }
  const balance = await alchemy.core.getBalance(address);
  res.json({ balance: balance.toString() });
});

// Alchemy Dashboard: restrict API key to specific domains/IPs
// Dashboard > App > Settings > Allowed Domains

Step 2: Input Validation for Blockchain Queries

// src/security/validators.ts
import { ethers } from 'ethers';

function validateAddress(input: string): string {
  if (!ethers.isAddress(input)) throw new Error(`Invalid address: ${input}`);
  return ethers.getAddress(input); // Returns checksummed address
}

function validateBlockNumber(input: string | number): string {
  if (input === 'latest' || input === 'pending' || input === 'earliest') return input;
  const num = typeof input === 'string' ? parseInt(input) : input;
  if (isNaN(num) || num < 0) throw new Error(`Invalid block number: ${input}`);
  return `0x${num.toString(16)}`;
}

function validateTokenId(input: string): string {
  if (!/^\d+$/.test(input) && !input.startsWith('0x')) {
    throw new Error(`Invalid token ID: ${input}`);
  }
  return input;
}

export { validateAddress, validateBlockNumber, validateTokenId };

Step 3: Private Key Safety
                
              

                

                  
                    
                  
                  
                  alchemy-upgrade-migration
                  SKILL.md
                  View full skill →
                
                

                  
'Migrate from alchemy-sdk v2 to v3 and handle breaking changes.
                  

                      ReadWriteEditBash(npm:*)Grep
                    
                
                

                  
Alchemy Upgrade & Migration
Overview
Migration guide for Alchemy SDK upgrades and deprecated package transitions. The alchemy-web3 package is deprecated — migrate to alchemy-sdk.
Migration Paths

From
To
Complexity


alchemy-web3
alchemy-sdk
High (different API surface)


alchemy-sdk v2 → v3
alchemy-sdk v3
Medium (some breaking changes)


Direct JSON-RPC
alchemy-sdk
Low (SDK wraps same methods)


Instructions
Step 1: Migrate from alchemy-web3 to alchemy-sdk

// BEFORE: alchemy-web3 (DEPRECATED)
// import { createAlchemyWeb3 } from '@alch/alchemy-web3';
// const web3 = createAlchemyWeb3(`https://eth-mainnet.g.alchemy.com/v2/${apiKey}`);
// const balance = await web3.eth.getBalance(address);
// const nfts = await web3.alchemy.getNfts({ owner });

// AFTER: alchemy-sdk
import { Alchemy, Network } from 'alchemy-sdk';

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

// Core methods — same JSON-RPC, different API
const balance = await alchemy.core.getBalance(address);

// Enhanced APIs — reorganized under namespaces
const nfts = await alchemy.nft.getNftsForOwner(owner);

// WebSockets — now under alchemy.ws
alchemy.ws.on({ method: 'eth_subscribe', params: ['newHeads'] }, (block) => {
  console.log('New block:', block);
});

Step 2: API Surface Changes

// Key namespace changes in alchemy-sdk:

// Core (JSON-RPC wrapper)
alchemy.core.getBlockNumber();
alchemy.core.getBalance(address);
alchemy.core.getTokenBalances(address);
alchemy.core.getTokenMetadata(contractAddress);
alchemy.core.getAssetTransfers({ fromAddress, category });

// NFT (dedicated namespace)
alchemy.nft.getNftsForOwner(owner);
alchemy.nft.getNftsForContract(contract);
alchemy.nft.getContractMetadata(contract);
alchemy.nft.getNftMetadataBatch(tokens);
alchemy.nft.getOwnersForNft(contract, tokenId);

// WebSocket (real-time)
alchemy.ws.on(filter, callback);
alchemy.ws.once(filter, callback);
alchemy.ws.removeAllListeners();

// Notify (webhooks — requires authToken)
alchemy.notify.getAllWebhooks();
alchemy.notify.createWebhook(config);

Step 3: Dependency Cleanup

# Remove deprecated packages
npm uninstall @alch/alchemy-web3 alchemy-web3

# Install current SDK
npm install alchemy-sdk

# Check for leftover imports
grep -rn "alchemy-web3\|@alch/alchemy" src/ --include='*.ts' --include='*.js'

# Update ethers if needed (alchemy-sdk works with ethers v5 and v6)
npm install ethers@6

Step 
                
              

                

                  
                    
                  
                  
                  alchemy-webhooks-events
                  SKILL.md
                  View full skill →
                
                

                  
'Implement Alchemy Notify webhooks for real-time blockchain event notifications.
                  

                      ReadWriteEditBash(curl:*)
                    
                
                

                  
Alchemy Webhooks & Events (Notify API)
Overview
Alchemy Notify provides real-time push notifications for on-chain events. Instead of polling, receive webhook callbacks for wallet activity, mined transactions, dropped transactions, and smart contract events.
Webhook Types

Type
Trigger
Use Case


Address Activity
ETH/token transfer to/from address
Wallet notifications


Mined Transaction
Transaction confirmed on-chain
Payment confirmation


Dropped Transaction
Transaction removed from mempool
Failed tx alerting


NFT Activity
NFT transfer events
Marketplace notifications


Custom Webhook
GraphQL-defined filter
Complex event tracking


Instructions
Step 1: Create Webhook via Dashboard or API

# Create Address Activity webhook via Alchemy API
curl -X POST "https://dashboard.alchemy.com/api/create-webhook" \
  -H "X-Alchemy-Token: ${ALCHEMY_AUTH_TOKEN}" \
  -H "Content-Type: application/json" \
  -d '{
    "network": "ETH_MAINNET",
    "webhook_type": "ADDRESS_ACTIVITY",
    "webhook_url": "https://your-app.com/webhooks/alchemy",
    "addresses": [
      "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"
    ]
  }'

Step 2: Webhook Handler with Signature Verification

// src/webhooks/alchemy-handler.ts
import express from 'express';
import crypto from 'crypto';

const router = express.Router();

router.post('/webhooks/alchemy',
  express.raw({ type: 'application/json' }),
  async (req, res) => {
    // Verify webhook signature
    const signature = req.headers['x-alchemy-signature'] as string;
    if (!verifySignature(req.body.toString(), signature)) {
      return res.status(401).json({ error: 'Invalid signature' });
    }

    const event = JSON.parse(req.body.toString());
    await processAlchemyEvent(event);
    res.status(200).json({ ok: true });
  }
);

function verifySignature(body: string, signature: string): boolean {
  const signingKey = process.env.ALCHEMY_WEBHOOK_SIGNING_KEY!;
  const hmac = crypto.createHmac('sha256', signingKey);
  hmac.update(body, 'utf8');
  const digest = hmac.digest('hex');
  return crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(digest));
}

Step 3: Event Router

// src/webhooks/event-router.ts
interface AlchemyWebhookEvent {
  webhookId: string;
  id: string;
  createdAt: string;
  type: 'ADDRESS_ACTIVITY' | 'MINED_TRANSACTION' | 'DROPPED_TRANSACTION' 

                

              

          

        

      
      

      
      

      
      

      
      

  
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