eth-scan

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 0x86f25b64e1fe4c5162cdeed5245575d32ec549db on the Ethereum mainnet, Goerli, Kovan, Rinkeby and Ropsten.

It can use Web3.js, Ethers.js or regular HTTP as 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.

Getting started

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

yarn add @mycrypto/eth-scan

or

npm install @mycrypto/eth-scan

Example

import { getEtherBalances } from 'eth-scan';

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

Results in:

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

API

getEtherBalances(provider, addresses, options)

Get Ether balances for addresses.

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

• 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.

getTokenBalances(provider, addresses, token, options)

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 or JSONRPC endpoint.

• 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.

getTokensBalance(provider, address, tokens, options)

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 or JSONRPC endpoint.

• 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.

getTokensBalances(provider, addresses, tokens, options)

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

• 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.

EthScanOptions

• contractAddress <string> (optional) - The address of the smart contract to use. Defaults to 0x86f25b64e1fe4c5162cdeed5245575d32ec549db.

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

BalanceMap

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

Providers

Currently, eth-scan has support for three 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

Compatiblity

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.