Alchemy SDK for Javascript

Alchemy SDK helps developers use Alchemy's APIs and endpoints more efficiently. This is a lightweight, modular SDK built as a drop-in replacement of Ethers.js that provides a superset of functionality - enabling access to the Alchemy NFT API, Websockets, and Enhanced API methods.

It also provides access to Alchemy's hardened node infrastructure, guaranteeing reliability, scalability, and quality-of-life improvements such as automatic exponential backoff retries.

Note that the SDK is still in public beta. Alchemy reserves the right to (and almost certainly will) make breaking API changes in subsequent releases (don't write production code around it just yet).

Getting started

npm install @alch/alchemy-sdk

After installing the app, you can then import and use the SDK:

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

// Optional Config object, but defaults to demo api-key and eth-mainnet.
const settings = {
  apiKey: 'demo', // Replace with your Alchemy API Key.
  network: Network.ETH_MAINNET, // Replace with your network.
  maxRetries: 10
};

const alchemy = new Alchemy(settings);

You can access each method using the following pattern. Methods supported include:

• All commonly-used Ethers.js methods
• Alchemy NFT API methods
• Alchemy Enhanced API methods

If you are already using Ethers.js, you should be simply able to replace the Ethers.js object with the Alchemy object and it should just work.

// Initializing the alchemy config object
import { Alchemy } from '@alch/alchemy-sdk';

// Using default settings - pass in a settings object to specify your API key and network
const alchemy = new Alchemy(); 

// Access standard Ethers.js JSON-RPC node requests
alchemy.getBlockNumber().then(console.log);

// Access Alchemy-specific NFT API or Enhanced API requests
alchemy.getNftsForOwner('0xshah.eth').then(console.log);

Preventing Breaking Changes

The SDK is currently in public beta, and will undergo breaking changes before its official release. To protect your project from breaking changes, make sure to pin the version of the SDK you are using in your package.json file. Please check the release notes to see if any breaking changes have been made. While the SDK in the public beta, minor versions may contain breaking changes, but patch versions under the same minor version should be safe to use interchangeably.

For example, to pin to a specific version of the SDK in your package.json file:

{
  "dependencies": {
    "@alch/alchemy-sdk": "1.1.0"
  }
}

SDK Structure

The Alchemy object returned by new Alchemy() provides access to the Alchemy API. An optional config object can be passed in when initializing to set your API key, change the network, or specify the max number of retries.

There are two different patterns for the Alchemy object to be used:

1. The Alchemy object enables access to methods like alchemy.getNftsForOwner() or alchemy.getBlockNumber(). This pattern current supports nearly all Ethers.js methods with a 1:1 mapping, the Alchemy NFT API endpoints, and the Alchemy Enhanced APIs.

2. In the case that an Ethers.js method is not supported on the top-level, the Alchemy object can be used to generate an Ethers.js provider that allows access to less-common Ethers.js methods.

Accessing the full Ethers.js provider

To keep the package clean, we don't support certain uncommonly-used Ethers.js methods as top-level methods the Alchemy object - for example, provider.formatter. If you'd like to access these methods, simply use the alchemy.getProvider() function to configure the Ethers.js AlchemyProvider and return it.

import { Alchemy } from '@alch/alchemy-sdk';

const alchemy = new Alchemy();

async function runAlchemy() {
  const ethersProvider = await alchemy.getProvider();
  console.log(ethersProvider.formatter);
}
runAlchemy();

Websockets and Subscription Listeners

In addition to the built-in Ethers.js listeners, the Alchemy SDK includes support for Alchemy's Subscription API. This allows you to subscribe to events and receive updates as they occur. The main subscription API is alchemy_pendingTransactions.

The top level Alchemy instance can be used can be used like the standard Ethers.js WebSocketProvider to add listeners for Alchemy events:

import { Alchemy } from '@alch/alchemy-sdk';

const alchemy = new Alchemy();

// Listen to all new pending transactions.
alchemy.on(
  {
    method: 'alchemy_pendingTransactions'
  },
  res => console.log(res)
);

// Listen to only the next transaction on the USDC contract.
alchemy.once(
  {
    method: 'alchemy_pendingTransactions',
    toAddress: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48'
  },
  res => console.log(res)
);

// Remove all listeners.
alchemy.removeAllListeners();

The SDK brings multiple improvements to ensure correct WebSocket behavior in cases of temporary network failure or dropped connections. As with any network connection, you should not assume that a WebSocket will remain open forever without interruption, but correctly handling dropped connections and reconnection by hand can be challenging to get right. alchemy-sdk automatically handles these failures with no configuration necessary. The main benefits are:

• Resilient event delivery: Unlike standard Web3.js or Ethers.js, you will not permanently miss events which arrive while the backing WebSocket is temporarily down. Instead, you will receive these events as soon as the connection is reopened. Note that if the connection is down for more than 120 blocks (approximately 20 minutes), you may still miss some events that were not part of the most recent 120 blocks.
• Lowered rate of failure: Compared to standard Web3.js or Ethers.js, there are fewer failures when sending requests over the WebSocket while the connection is down. Alchemy Web3 will attempt to send the requests once the connection is reopened. Note that it is still possible, with a lower likelihood, for outgoing requests to be lost, so you should still have error handling as with any network request.

NFT Module

The SDK currently supports the following NFT API endpoints under the Alchemy class:

• getNftMetadata(): Get the NFT metadata for a contract address and tokenId.
• getNftContractMetadata(): Get the metadata associated with an NFT contract
• getNftsForOwner(): Get NFTs for an owner address.
• getNftsForOwnerIterator(): Get NFTs for an owner address as an async iterator (handles paging automatically).
• getNftsForNftContract(): Get all NFTs for a contract address.
• getNftForNftContractIterator(): Get all NFTs for a contract address as an async iterator (handles paging automatically).
• getOwnersForNft(): Get all the owners for a given NFT contract address and a particular token ID.
• getOwnersForNftContract(): Get all the owners for a given NFT contract address.
• checkNftOwnership(): Check that the provided owner address owns one or more of the provided NFT contract addresses.
• isSpamNftContract(): Check whether the given NFT contract address is a spam contract as defined by Alchemy (see the NFT API FAQ)
• getSpamNftContracts(): Returns a list of all spam contracts marked by Alchemy.
• findContractDeployer(): Find the contract deployer and block number for a given NFT contract address.
• refreshNftMetadata(): Refresh the cached NFT metadata for a contract address and a single tokenId.
• refreshNftContract(): Enqueues the specified contract address to have all token ids' metadata refreshed.
• getNftFloorPrice(): Return the floor prices of a NFT contract by marketplace.

Comparing BaseNft and Nft

The SDK currently uses the BaseNft and Nft classes to represent NFTs returned by the Alchemy. The BaseNft object does not hold any metadata information and only contains the NFT contract and token ID. The Nft object additionally contains the NFT metadata, token URI information, and media.

By default, the SDK will return the Nft object. You can optionally choose to fetch the BaseNft object instead by setting the omitMetadata parameter to true. The SDK documentation describes the different parameter and response interfaces in more detail.

Pagination

The Alchemy NFT endpoints return 100 results per page. To get the next page, you can pass in the pageKey returned by the previous call. To simplify paginating through all results, the SDK provides the getNftsIterator() and getNftsForNftContractIterator() functions that automatically paginate through all NFTs and yields them via an AsyncIterable.

Here's an example of how to paginate through all the NFTs in Vitalik's ENS address:

import { Alchemy } from '@alch/alchemy-sdk';

const alchemy = new Alchemy();

async function main() {
  const ownerAddress = 'vitalik.eth';
  for await (const nft of alchemy.getNftsForOwnerIterator(ownerAddress)) {
    console.log('ownedNft:', nft);
  }
}

main();

SDK vs API Differences

The NFT API in the SDK standardizes response types to reduce developer friction, but note this results in some differences compared to the Alchemy REST endpoints:

• Methods referencing Collection have been renamed to use the name NftContract for greater accuracy: e.g. getNftsForNftContract.
• Some methods have different naming that the REST API counterparts in order to provide a consistent API interface ( e.g. getNftsForOwner() is alchemy_getNfts, getOwnersForNft() is alchemy_getOwnersForToken).
• SDK standardizes to omitMetadata parameter (vs. withMetadata).
• Standardization to pageKey parameter for pagination (vs. nextToken/startToken)
• Empty TokenUri fields are omitted.
• Token ID is always normalized to an integer string on BaseNft and Nft.
• Some fields omitted in the REST response are included in the SDK response in order to return an Nft object.
• Some fields in the SDK's Nft object are named differently than the REST response.

Documentation

The SDK is documented via tsdoc comments in the source code. The generated types and documentation are included when using an IDE. To browse the documentation separately, you can view the generated API interfaces in etc/alchemy-sdk.api.md. You can view generated Markdown files for each endpoint in the docs-md directory, or as a webpage by opening docs/index.html in your browser.

Future Work

There's a long list, but here are the main ones:

• Retry count support for json-rpc calls (currently only for NFT API calls).
• More config options for the base ethers.js AlchemyProvider.

Examples

Below are a few usage examples:

Getting the NFTs owned by an address.

import {
  NftExcludeFilters,
  Alchemy
} from '@alch/alchemy-sdk';

const alchemy = new Alchemy();

// Get how many NFTs an address owns.
alchemy.getNftsForOwner('0xshah.eth').then(nfts => {
  console.log(nfts.totalCount);
});

// Get all the image urls for all the NFTs an address owns.
async function main() {
  for await (const nft of alchemy.getNftsForOwnerIterator('0xshah.eth')) {
    console.log(nft.media);
  }
}

main();

// Filter out spam NFTs.
alchemy.getNftsForOwner('0xshah.eth', {
  excludeFilters: [NftExcludeFilters.SPAM]
}).then(console.log);

Getting all the owners of the BAYC NFT.

import {
  Alchemy
} from '@alch/alchemy-sdk';

const alchemy = new Alchemy();

// Bored Ape Yacht Club contract address.
const baycAddress = '0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D';

async function main() {
  for await (const nft of alchemy.getNftsForNftContractIterator(baycAddress, {
    // Omit the NFT metadata for smaller payloads.
    omitMetadata: true
  })) {
    await alchemy.getOwnersForNft(nft).then(response =>
      console.log('owners:', response.owners, 'tokenId:', nft.tokenId)
    );
  }
}

main();

Get all outbound transfers for a provided address.

import { Alchemy } from '@alch/alchemy-sdk';

const alchemy = new Alchemy();

alchemy.getTokenBalances('0x994b342dd87fc825f66e51ffa3ef71ad818b6893').then(
  console.log
);

Questions and Feedback

If you have any questions, issues, or feedback, please file an issue on GitHub, or drop us a message on our Discord channel for the SDK.