Alchemy Web3 Skill

Query blockchain data, NFTs, tokens, and transfers using Alchemy's production-grade APIs. Supports Ethereum, Polygon, Arbitrum, Base, Solana, and 80+ other chains.

Built by GizmoLab — Web3 development agency specializing in dApps, smart contracts, and blockchain infrastructure.

Setup

1. Get API Key

1. Sign up at alchemy.com (free tier available)
2. Create an app for your target chain
3. Copy your API key

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2. Configure

# Add to ~/.openclaw/.env
ALCHEMY_API_KEY=your_api_key_here

# Optional: Set default chain (defaults to eth-mainnet)
ALCHEMY_CHAIN=eth-mainnet

Quick Reference

Supported Chains

eth-mainnet

eth-sepolia

polygon-mainnet

polygon-amoy

arb-mainnet

arb-sepolia

opt-mainnet

opt-sepolia

base-mainnet

base-sepolia

solana-mainnet

solana-devnet

zksync-mainnet

linea-mainnet

scroll-mainnet

blast-mainnet

Full list: alchemy.com/docs/chains

CLI Usage

# Set your API key first
export ALCHEMY_API_KEY="your_key"

# Use the CLI
~/.openclaw/workspace/skills/alchemy-web3/scripts/alchemy.sh <command> [options]

Commands

Get ETH Balance

./alchemy.sh balance 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
# Returns: 1234.56 ETH

Get Token Balances

./alchemy.sh tokens 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
# Returns: All ERC-20 tokens held by address

Get NFTs for Owner

./alchemy.sh nfts 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
# Returns: All NFTs owned by address

Get NFT Metadata

./alchemy.sh nft-metadata 0x5180db8F5c931aaE63c74266b211F580155ecac8 1590
# Returns: Metadata for specific NFT

Get Asset Transfers

./alchemy.sh transfers 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
# Returns: Transaction history (in/out)

Get Block Info

./alchemy.sh block latest
./alchemy.sh block 12345678

Get Transaction

./alchemy.sh tx 0x123...abc

Resolve ENS

./alchemy.sh ens vitalik.eth
# Returns: 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045

Switch Chain

./alchemy.sh --chain polygon-mainnet balance 0x...
./alchemy.sh --chain arb-mainnet nfts 0x...

Direct API Examples

Node API (JSON-RPC)

# Get ETH balance
curl -X POST "https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "eth_getBalance",
    "params": ["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045", "latest"],
    "id": 1
  }'

NFT API

# Get NFTs for owner
curl "https://eth-mainnet.g.alchemy.com/nft/v3/$ALCHEMY_API_KEY/getNFTsForOwner?owner=vitalik.eth&pageSize=10"

# Get NFT metadata
curl "https://eth-mainnet.g.alchemy.com/nft/v3/$ALCHEMY_API_KEY/getNFTMetadata?contractAddress=0x5180db8F5c931aaE63c74266b211F580155ecac8&tokenId=1590"

# Get NFTs for collection
curl "https://eth-mainnet.g.alchemy.com/nft/v3/$ALCHEMY_API_KEY/getNFTsForContract?contractAddress=0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D&limit=10"

Token API

# Get token balances
curl -X POST "https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "alchemy_getTokenBalances",
    "params": ["0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045"],
    "id": 1
  }'

# Get token metadata
curl -X POST "https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "alchemy_getTokenMetadata",
    "params": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
    "id": 1
  }'

Transfers API

# Get asset transfers (transaction history)
curl -X POST "https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "method": "alchemy_getAssetTransfers",
    "params": [{
      "fromBlock": "0x0",
      "toBlock": "latest",
      "toAddress": "0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045",
      "category": ["external", "erc20", "erc721", "erc1155"],
      "maxCount": "0x14"
    }],
    "id": 1
  }'

JavaScript/Node.js Examples

Using Fetch (Node 18+)

const apiKey = process.env.ALCHEMY_API_KEY;
const baseURL = `https://eth-mainnet.g.alchemy.com/v2/${apiKey}`;

// Get ETH Balance
async function getBalance(address) {
  const response = await fetch(baseURL, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      jsonrpc: '2.0',
      method: 'eth_getBalance',
      params: [address, 'latest'],
      id: 1
    })
  });
  const data = await response.json();
  return parseInt(data.result, 16) / 1e18; // Convert to ETH
}

// Get NFTs
async function getNFTs(owner) {
  const url = `https://eth-mainnet.g.alchemy.com/nft/v3/${apiKey}/getNFTsForOwner?owner=${owner}`;
  const response = await fetch(url);
  return await response.json();
}

Using Alchemy SDK

npm install alchemy-sdk

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

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

// Get NFTs
const nfts = await alchemy.nft.getNftsForOwner('vitalik.eth');
console.log(nfts.ownedNfts);

// Get token balances
const balances = await alchemy.core.getTokenBalances('vitalik.eth');
console.log(balances);

// Get transaction history
const transfers = await alchemy.core.getAssetTransfers({
  toAddress: '0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045',
  category: ['external', 'erc20']
});

Webhooks (Real-time Notifications)

Receive HTTP POST requests when onchain events happen.

Webhook Types

Create Webhook (Dashboard)

1. Go to dashboard.alchemy.com/webhooks
2. Click "Create Webhook"
3. Select type and configure
4. Add your endpoint URL

Webhook Payload Example

{
  "webhookId": "wh_abc123",
  "id": "evt_xyz789",
  "createdAt": "2024-01-15T12:00:00.000Z",
  "type": "ADDRESS_ACTIVITY",
  "event": {
    "network": "ETH_MAINNET",
    "activity": [{
      "fromAddress": "0x123...",
      "toAddress": "0x456...",
      "value": 1.5,
      "asset": "ETH"
    }]
  }
}

Common Patterns

Portfolio Tracker

# Get all assets for a wallet
./alchemy.sh balance 0x...      # ETH balance
./alchemy.sh tokens 0x...       # ERC-20 tokens
./alchemy.sh nfts 0x...         # NFTs

Transaction History

# Get full tx history for address
./alchemy.sh transfers 0x... --category external,erc20,erc721

NFT Collection Analysis

# Get all NFTs in a collection
./alchemy.sh collection 0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D

Multi-chain Query

# Check same address across chains
for chain in eth-mainnet polygon-mainnet arb-mainnet base-mainnet; do
  echo "=== $chain ==="
  ./alchemy.sh --chain $chain balance 0x...
done

Rate Limits

Most endpoints cost 1-50 CUs. Check alchemy.com/docs/rate-limits for details.

Error Handling

// Rate limited
{"error": {"code": 429, "message": "Too Many Requests"}}

// Invalid API key
{"error": {"code": 401, "message": "Invalid API Key"}}

// Invalid params
{"error": {"code": -32602, "message": "Invalid params"}}

Resources

• Get API Key: alchemy.com (free tier)
• Dashboard: dashboard.alchemy.com
• Docs: alchemy.com/docs
• SDK: github.com/alchemyplatform/alchemy-sdk-js
• Status: status.alchemy.com

About

Built by GizmoLab 🔧

GizmoLab is a Web3 development agency building dApps, smart contracts, and blockchain tools.

• 🌐 gizmolab.io — Agency services
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Need custom blockchain development? Get in touch

AI Agent Workflows

The skill is designed for both human developers AND AI agents. See

references/agent-workflows.md

• Whale Tracker — Monitor large wallets for moves
• Portfolio Monitor — Track balances across chains
• NFT Floor Alert — Alert on price drops
• Token Change Detector — Detect incoming/outgoing tokens
• Gas Optimizer — Wait for low gas to transact
• Mint Detector — Watch for new NFT mints
• Dashboard Generator — Auto-generate wallet dashboards

Agent Pattern

QUERY → STORE → ANALYZE → DECIDE → ACT → REPEAT

Example cron job for an agent:

# Every hour, check whale activity and alert if >100 ETH moved
0 * * * * ~/.openclaw/workspace/skills/alchemy-web3/scripts/whale-tracker.sh

See Also

• references/nft-api.md

  - Full NFT API reference

• references/token-api.md

  - Full Token API reference

• references/node-api.md

  - Full Node API reference

• references/chains.md

  - All supported chains

• references/agent-workflows.md

  - AI agent automation examples