eth-scan is a library written in TypeScript, to help you fetch Ether or (ERC-20) token balances for multiple addresses in an efficient way. The library uses a smart contract to fetch the balances in a single call to a node. The contract is currently deployed at:

• 0x08A8fDBddc160A7d5b957256b903dCAb1aE512C5 on the Ethereum mainnet, Goerli, Kovan, Rinkeby, Ropsten, Polygon, Gnosis, Avalanche and RSK.
• 0x9e5076DF494FC949aBc4461F4E57592B81517D81 on Optimism.

It can use Web3.js, Ethers.js, JSON-RPC (HTTP), or an EIP-1193-compatible provider to get the balances. See Getting Started for more info.

Note: Even though eth_call doesn't use any gas, the block gas limit still applies, and the maximum number of addresses you can fetch in a single call is limited. By default this library batches calls per 1000 addresses.

The library is published on npm. To install it, use npm or yarn:

yarn add @mycrypto/eth-scan

or

npm install @mycrypto/eth-scan

import { getEtherBalances } from '@mycrypto/eth-scan';

getEtherBalances('http://127.0.0.1:8545', [
  '0x9a0decaffb07fb500ff7e5d253b16892dbec006a',
  '0xeb65f72a2f5464157288ac15f1bb56c56e6be375',
  '0x1b96c634f9e9fcfb76932e165984901701352ffd',
  '0x740539b55ee5dc58efffb88fea44a9008f8daa6f',
  '0x95d9e32dc03770699a6a5e5858165b174d500015'
]).then(console.log);

Results in:

{
  '0x9a0decaffb07fb500ff7e5d253b16892dbec006a': BigInt(1000000000000000000),
  '0xeb65f72a2f5464157288ac15f1bb56c56e6be375': BigInt(1000000000000000000),
  '0x1b96c634f9e9fcfb76932e165984901701352ffd': BigInt(1000000000000000000),
  '0x740539b55ee5dc58efffb88fea44a9008f8daa6f': BigInt(1000000000000000000),
  '0x95d9e32dc03770699a6a5e5858165b174d500015': BigInt(1000000000000000000)
}

Get Ether balances for addresses.

• provider <Provider> - A Web3 instance, Ethers.js provider, JSONRPC endpoint, or EIP-1193 compatible provider

• addresses <string[]> - An array of addresses as hexadecimal string.

• options <EthScanOptions> (optional) - The options to use.

• Returns: <Promise<BalanceMap>> - A promise with an object with the addresses and the balances.

Get ERC-20 token balances from token for addresses. This does not check if the address specified is a token and will throw an error if it isn't.

• provider <Provider> - A Web3 instance, Ethers.js provider, JSONRPC endpoint, or EIP-1193 compatible provider

• addresses <string[]> - An array of addresses as hexadecimal string.

• token <string> - The address of the ERC-20 token.

• options <EthScanOptions> (optional) - The options to use.

• Returns: <Promise<BalanceMap>> - A promise with an object with the addresses and the balances.

Get ERC-20 token balances from tokens for address. If one of the token addresses specified is not a token, a balance of 0 will be used.

• provider <Provider> - A Web3 instance, Ethers.js provider, JSONRPC endpoint, or EIP-1193 compatible provider

• address <string> - The address to get token balances for.

• tokens <string[]> - An array of ERC-20 token addresses.

• options <EthScanOptions> (optional) - The options to use.

• Returns: <Promise<BalanceMap>> - A promise with an object with the addresses and the balances.

• provider <Provider> - A Web3 instance, Ethers.js provider, JSONRPC endpoint, or EIP-1193 compatible provider.

• addresses <string[]> - An array of addresses as hexadecimal string.

• tokens <string[]> - An array of ERC-20 token addresses.

• options <EthScanOptions> (optional) - The options to use.

• Returns: <Promise<BalanceMap<BalanceMap>>> - A promise with an object with the addresses and the balances.

• contractAddress <string> (optional) - The address of the smart contract to use. Defaults to 0x08A8fDBddc160A7d5b957256b903dCAb1aE512C5.

• batchSize <number> (optional) - The size of the call batches. Defaults to 1000.

A BalanceMap is an object with an address as key and a bigint as value.

Currently, eth-scan has support for four different providers:

• Ethers.js, by using an existing Ethers.js provider
• Web3, by using an instance of the Web3 class
• HTTP, by using a URL of a JSONRPC endpoint as string
• EIP-1193 compatible provider, like window.ethereum

eth-scan uses ES6+ functionality, which may not be supported on all platforms. If you need compatibility with older browsers or Node.js versions, you can use something like Babel.

There is an ES compatible version available, which should work with module bundlers like Webpack and Rollup.