alchemy

What this skill does

# 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](https://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](#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.

---

## 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](references/x402/overview.md) — End-to-end flow and packages
- [references/x402/wallet-bootstrap.md](references/x402/wallet-bootstrap.md) — Wallet setup and USDC funding
- [references/x402/authentication.md](references/x402/authentication.md) — SIWE/SIWS token creation
- [references/x402/making-requests.md](references/x402/making-requests.md) — Sending requests with `@x402/fetch`
- [references/x402/curl-workflow.md](references/x402/curl-workflow.md) — Quick RPC calls via curl
- [references/x402/payment.md](references/x402/payment.md) — Payment creation from a 402 response
- [references/x402/reference.md](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](references/mpp/overview.md) — End-to-end flow and packages
- [references/mpp/wallet-bootstrap.md](references/mpp/wallet-bootstrap.md) — Wallet setup and funding
- [references/mpp/authentication.md](references/mpp/authentication.md) — SIWE token creation
- [references/mpp/making-requests.md](references/mpp/making-requests.md) — Sending requests with `mppx`
- [references/mpp/curl-workflow.md](references/mpp/curl-workflow.md) — Quick RPC calls via curl
- [references/mpp/payment.md](references/mpp/payment.md) — Payment creation from a 402 response
- [references/mpp/reference.md](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)
```bash
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
```bash
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
```bash
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
```bash
curl -s "https://eth-mainnet.g.alchemy.com/nft/v3/$ALCHEMY_API_KEY/getN