Alchemy Web3

Interact with Alchemy's Web3 APIs for blockchain data, NFTs, tokens, transfers, and webhooks across 80+ chains.

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

bash

# 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

Chain	Endpoint Prefix
Ethereum	eth-mainnet, eth-sepolia
Polygon	polygon-mainnet, polygon-amoy
Arbitrum	arb-mainnet, arb-sepolia
Optimism	opt-mainnet, opt-sepolia
Base	base-mainnet, base-sepolia
Solana	solana-mainnet, solana-devnet
zkSync	zksync-mainnet
Linea	linea-mainnet
Scroll	scroll-mainnet
Blast	blast-mainnet

Full list: alchemy.com/docs/chains

CLI Usage

bash

# 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

bash

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

Get Token Balances

bash

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

Get NFTs for Owner

bash

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

Get NFT Metadata

bash

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

Get Asset Transfers

bash

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

Get Block Info

bash

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

Get Transaction

bash

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

Resolve ENS

bash

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

Switch Chain

bash

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

Direct API Examples

Node API (JSON-RPC)

bash

# 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

bash

# 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

bash

# 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

bash

# 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+)

javascript

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

bash

npm install alchemy-sdk

javascript

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

Type	Use Case
Address Activity	Track transfers to/from specific addresses
NFT Activity	Track NFT sales, transfers, mints
Mined Transactions	Track when your txs are mined
Dropped Transactions	Get notified if tx is dropped
Gas Price	Alert on gas price thresholds

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

json

{
  "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

bash

# 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

bash

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

NFT Collection Analysis

bash

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

Multi-chain Query

bash

# 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

Plan	Compute Units/sec	Monthly CUs
Free	330	300M
Growth	660	Unlimited
Scale	Custom	Custom

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

Error Handling

json

// 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.

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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 for complete examples:

• 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

text

QUERY → STORE → ANALYZE → DECIDE → ACT → REPEAT

Example cron job for an agent:

bash

# 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