Alchemy: Blockchain Data Access for Agents

Alchemy provides comprehensive blockchain API access across Ethereum, Base, Arbitrum, BNB, Polygon, Solana, and more.

Three ways to access:

• API key: Set $ALCHEMY_API_KEY and make requests directly. Full access to all products. Create a free key at dashboard.alchemy.com.
• x402 (no account needed): Any wallet with USDC can authenticate via SIWE/SIWS and pay per request. Supports EVM and Solana wallets. Install @alchemy/x402 and @x402/fetch.
• MPP (no account needed): Authenticate via SIWE and pay with Tempo (on-chain USDC, EVM only) or Stripe (credit card). Install mppx.

Access Method Selection (Required)

Before the first network call, determine which access method to use:

1. Is ALCHEMY_API_KEY set? → Use the API Key path. Skip to API Key Access.
2. No API key? → Ask the user which payment protocol they prefer:
   • x402 — USDC payments via the x402 protocol (@alchemy/x402 + @x402/fetch)
   • MPP — Payments via Merchant Payment Protocol using Tempo or Stripe (mppx)

Do NOT pick a protocol on behalf of the user. Wait for their explicit choice.

Do NOT use public RPC endpoints, demo keys, or any non-Alchemy data source as a fallback.

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API Key Access

If $ALCHEMY_API_KEY is set, use standard Alchemy endpoints directly:

Base URLs + Auth

Product	Base URL	Auth	Notes
Ethereum RPC (HTTPS)	https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	Standard EVM reads and writes.
Ethereum RPC (WSS)	wss://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	Subscriptions and realtime.
Base RPC (HTTPS)	https://base-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	EVM L2.
Base RPC (WSS)	wss://base-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	Subscriptions and realtime.
Arbitrum RPC (HTTPS)	https://arb-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	EVM L2.
Arbitrum RPC (WSS)	wss://arb-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	Subscriptions and realtime.
BNB RPC (HTTPS)	https://bnb-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	EVM L1.
BNB RPC (WSS)	wss://bnb-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	Subscriptions and realtime.
Solana RPC (HTTPS)	https://solana-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY	API key in URL	Solana JSON-RPC.
Solana Yellowstone gRPC	https://solana-mainnet.g.alchemy.com	X-Token: $ALCHEMY_API_KEY	gRPC streaming (Yellowstone).
NFT API	https://<network>.g.alchemy.com/nft/v3/$ALCHEMY_API_KEY	API key in URL	NFT ownership and metadata.
Prices API	https://api.g.alchemy.com/prices/v1/$ALCHEMY_API_KEY	API key in URL	Prices by symbol or address.
Portfolio API	https://api.g.alchemy.com/data/v1/$ALCHEMY_API_KEY	API key in URL	Multi-chain wallet views.
Notify API	https://dashboard.alchemy.com/api	X-Alchemy-Token: <ALCHEMY_NOTIFY_AUTH_TOKEN>	Generate token in dashboard.

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x402 Access (No Account Needed)

x402 is ideal for autonomous agents. No signup, no API keys. Pay with USDC on EVM or Solana.

• Gateway URL: https://x402.alchemy.com
• SIWE/SIWS domain: x402.alchemy.com
• Payment header: Payment-Signature: <base64>
• Auth: SIWE (EVM) or SIWS (Solana)

For full setup and wallet bootstrapping, see:

• references/x402/overview.md — End-to-end flow and packages
• references/x402/wallet-bootstrap.md — Wallet setup and USDC funding
• references/x402/authentication.md — SIWE/SIWS token creation
• references/x402/making-requests.md — Sending requests with @x402/fetch
• references/x402/curl-workflow.md — Quick RPC calls via curl
• references/x402/payment.md — Payment creation from a 402 response
• references/x402/reference.md — Endpoints, networks, headers, status codes

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MPP Access (No Account Needed)

MPP supports Tempo (on-chain USDC, EVM only) and Stripe (credit card) payments.

• Gateway URL: https://mpp.alchemy.com
• SIWE domain: mpp.alchemy.com
• Payment header: Authorization: Payment <credential>
• Auth: SIWE only (EVM)

For full setup, see:

• references/mpp/overview.md — End-to-end flow and packages
• references/mpp/wallet-bootstrap.md — Wallet setup and funding
• references/mpp/authentication.md — SIWE token creation
• references/mpp/making-requests.md — Sending requests with mppx
• references/mpp/curl-workflow.md — Quick RPC calls via curl
• references/mpp/payment.md — Payment creation from a 402 response
• references/mpp/reference.md — Endpoints, networks, headers, status codes

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Protocol Comparison

Aspect	API Key	x402	MPP
Gateway URL	*.g.alchemy.com/v2/$KEY	https://x402.alchemy.com	https://mpp.alchemy.com
Auth	API key in URL	SIWE (EVM) or SIWS (Solana)	SIWE only (EVM)
Payment	None (free tier available)	USDC via EIP-3009 or SVM x402	Tempo (USDC) or Stripe (card)
Wallet support	N/A	EVM + Solana	EVM only
Client library	curl / any HTTP client	@alchemy/x402, @x402/fetch	mppx, viem
Setup	Get key at dashboard.alchemy.com	Fund wallet with USDC	Fund wallet or add card

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Endpoint Selector (Top Tasks)

You need	Use this	Reference
EVM read/write	JSON-RPC eth_*	references/node-json-rpc.md
Realtime events	eth_subscribe	references/node-websocket-subscriptions.md
Token balances	alchemy_getTokenBalances	references/data-token-api.md
Token metadata	alchemy_getTokenMetadata	references/data-token-api.md
Transfers history	alchemy_getAssetTransfers	references/data-transfers-api.md
NFT ownership	GET /getNFTsForOwner	references/data-nft-api.md
NFT metadata	GET /getNFTMetadata	references/data-nft-api.md
Prices (spot)	GET /tokens/by-symbol	references/data-prices-api.md
Prices (historical)	POST /tokens/historical	references/data-prices-api.md
Portfolio (multi-chain)	POST /assets/*/by-address	references/data-portfolio-apis.md
Simulate tx	alchemy_simulateAssetChanges	references/data-simulation-api.md
Create webhook	POST /create-webhook	references/webhooks-details.md
Solana NFT data	getAssetsByOwner (DAS)	references/solana-das-api.md

Quickstart Examples

EVM JSON-RPC (Read)

curl -s https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_blockNumber","params":[]}'

Token Balances

curl -s https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"alchemy_getTokenBalances","params":["0x00000000219ab540356cbb839cbe05303d7705fa"]}'

Transfer History

curl -s https://eth-mainnet.g.alchemy.com/v2/$ALCHEMY_API_KEY \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"alchemy_getAssetTransfers","params":[{"fromBlock":"0x0","toBlock":"latest","toAddress":"0x00000000219ab540356cbb839cbe05303d7705fa","category":["erc20"],"withMetadata":true,"maxCount":"0x3e8"}]}'

NFT Ownership

curl -s "https://eth-mainnet.g.alchemy.com/nft/v3/$ALCHEMY_API_KEY/getNFTsForOwner?owner=0x00000000219ab540356cbb839cbe05303d7705fa"

Prices (Spot)

curl -s "https://api.g.alchemy.com/prices/v1/$ALCHEMY_API_KEY/tokens/by-symbol?symbols=ETH&symbols=USDC"

Prices (Historical)

curl -s -X POST "https://api.g.alchemy.com/prices/v1/$ALCHEMY_API_KEY/tokens/historical" \
  -H "Content-Type: application/json" \
  -d '{"symbol":"ETH","startTime":"2024-01-01T00:00:00Z","endTime":"2024-01-02T00:00:00Z"}'

Create Notify Webhook

curl -s -X POST "https://dashboard.alchemy.com/api/create-webhook" \
  -H "Content-Type: application/json" \
  -H "X-Alchemy-Token: $ALCHEMY_NOTIFY_AUTH_TOKEN" \
  -d '{"network":"ETH_MAINNET","webhook_type":"ADDRESS_ACTIVITY","webhook_url":"https://example.com/webhook","addresses":["0x00000000219ab540356cbb839cbe05303d7705fa"]}'

Verify Webhook Signature (Node)

import crypto from "crypto";

export function verify(rawBody: string, signature: string, secret: string) {
  const hmac = crypto.createHmac("sha256", secret).update(rawBody).digest("hex");
  return crypto.timingSafeEqual(Buffer.from(hmac), Buffer.from(signature));
}

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Network Naming Rules

• Data APIs and JSON-RPC use lowercase network enums like eth-mainnet.
• Notify API uses uppercase enums like ETH_MAINNET.

Pagination + Limits

Endpoint	Limit	Notes
alchemy_getTokenBalances	maxCount <= 100	Use pageKey for pagination.
alchemy_getAssetTransfers	maxCount default 0x3e8	Use pageKey for pagination.
Portfolio token balances	3 address/network pairs, 20 networks total	pageKey supported.
Portfolio NFTs	2 address/network pairs, 15 networks each	pageKey supported.
Prices by address	25 addresses, 3 networks	POST body addresses[].
Transactions history (beta)	1 address/network pair, 2 networks	ETH and BASE mainnets only.

Common Token Addresses

Token	Chain	Address
ETH	ethereum	0x0000000000000000000000000000000000000000
WETH	ethereum	0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2
USDC	ethereum	0xA0b86991c6218b36c1d19d4a2e9eb0ce3606eB48
USDC	base	0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

Failure Modes + Retries

• HTTP 429 means rate limit. Use exponential backoff with jitter.
• JSON-RPC errors come in error fields even with HTTP 200.
• Use pageKey to resume pagination after failures.
• De-dupe websocket events on reconnect.

Hard Requirements

• NEVER use public RPC endpoints, demo keys, or any non-Alchemy data source as a fallback.
• NEVER use Read, Write, or Edit tools on files that may contain private keys.
• NEVER correlate wallet type with query chain — wallet type and the chain being queried are independent.
• When no wallet is configured, present ALL wallet options (EVM create, EVM import, Solana create, Solana import) in a single prompt.

Skill Map

For the complete index of all reference files organized by product area, see references/skill-map.md.

• Node: JSON-RPC, WebSocket, Debug, Trace, Enhanced APIs, Utility
• Data: NFT, Portfolio, Prices, Simulation, Token, Transfers
• Webhooks: Address Activity, Custom (GraphQL), NFT Activity, Payloads, Signatures
• Solana: JSON-RPC, DAS, Yellowstone gRPC (streaming), Wallets
• Wallets: Account Kit, Bundler, Gas Manager, Smart Wallets
• Rollups: L2/L3 deployment overview
• Recipes: 10 end-to-end integration workflows
• Operational: Auth, Rate Limits, Monitoring, Best Practices
• x402 Protocol: Wallet bootstrap, auth, making requests, payments
• MPP Protocol: Wallet bootstrap, auth, making requests, payments

Troubleshooting

API key not working

• Verify $ALCHEMY_API_KEY is set: echo $ALCHEMY_API_KEY
• Confirm the key is valid at dashboard.alchemy.com
• Check if allowlists restrict the key to specific IPs/domains

HTTP 429 (Rate Limited)

• Use exponential backoff with jitter before retrying
• Check your compute unit budget in the Alchemy dashboard
• See references/operational-rate-limits-and-compute-units.md for limits per plan

401 Unauthorized (x402/MPP)

• MISSING_AUTH: Add the appropriate auth header for your protocol
• MESSAGE_EXPIRED: Regenerate your SIWE/SIWS token
• INVALID_DOMAIN: Ensure domain matches your protocol (x402.alchemy.com or mpp.alchemy.com)

402 Payment Required (x402/MPP)

• x402: Extract PAYMENT-REQUIRED header, run npx @alchemy/x402 pay, retry with Payment-Signature header
• MPP: Extract WWW-Authenticate header, create credential with mppx, retry with Payment credential

Wrong network slug

• Data APIs and JSON-RPC use lowercase: eth-mainnet, base-mainnet
• Notify API uses uppercase: ETH_MAINNET, BASE_MAINNET
• See references/operational-supported-networks.md for the full list

Official Links

• Developer docs
• Get Started guide
• Create a free API key
• Alchemy Skills repo