Alchemy: Blockchain Data Access for Agents Skill

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:

Is ALCHEMY_API_KEY set? → Use the API Key path. Skip to API Key Access.
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.

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. |

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

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

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 |

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));
}

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

Agent Skills: Alchemy: Blockchain Data Access for Agents

Install this agent skill to your local

Skill Files