• Installation
• Getting Started
• Module: [account]
• Module: [address]
• Module: [blobs]
• Module: [bytes]
• Module: [constants]
• Module: [db]
• Module: [genesis]
• Module: [internal]
• Module: [kzg]
• Module: [mapDB]
• Module: [request]
• Module: [signature]
• Module: [types]
• Module: [verkle]
• Module: [withdrawal]
• Browser
• API
• EthereumJS
• License

To obtain the latest version, simply require the project using npm:

npm install @ethereumjs/util

This package contains the following modules providing respective helper methods, classes and commonly re-used constants.

All helpers are re-exported from the root level and deep imports are not necessary. So an import can be done like this:

import { hexToBytes, isValidChecksumAddress } from '@ethereumjs/util'

Class representing an Account and providing private/public key and address-related functionality (creation, validation, conversion). It is not recommended to use this constructor directly. Instead use the static factory methods to assist in creating an Account from varying data types.

// ./examples/account.ts

import { createAccount } from '@ethereumjs/util'

const account = createAccount({
  nonce: '0x02',
  balance: '0x0384',
  storageRoot: '0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421',
  codeHash: '0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470',
})
console.log(`Account with nonce=${account.nonce} and balance=${account.balance} created`)

For Verkle or other contexts it can be useful to create partial accounts not containing all the account parameters. This is supported starting with v9.1.0:

// ./examples/accountPartial.ts

import { createPartialAccount } from '@ethereumjs/util'

const account = createPartialAccount({
  nonce: '0x02',
  balance: '0x0384',
})
console.log(`Partial account with nonce=${account.nonce} and balance=${account.balance} created`)

Class representing an Ethereum Address with instantiation helpers and validation methods.

// ./examples/address.ts

import { createAddressFromString } from '@ethereumjs/util'

const address = createAddressFromString('0x2f015c60e0be116b1f0cd534704db9c92118fb6a')
console.log(`Ethereum address ${address.toString()} created`)

Module providing helpers for 4844 blobs and versioned hashes.

// ./examples/blobs.ts

import { bytesToHex, computeVersionedHash, getBlobs } from '@ethereumjs/util'

const blobs = getBlobs('test input')

console.log('Created the following blobs:')
console.log(blobs)

const commitment = bytesToHex(new Uint8Array([1, 2, 3]))
const blobCommitmentVersion = 0x01
const versionedHash = computeVersionedHash(commitment, blobCommitmentVersion)

console.log(`Versioned hash ${versionedHash} computed`)

Byte-related helper and conversion functions.

// ./examples/bytes.ts

import { bytesToBigInt } from '@ethereumjs/util'

const bytesValue = new Uint8Array([97])
const bigIntValue = bytesToBigInt(bytesValue)

console.log(`Converted value: ${bigIntValue}`)

Exposed constants (e.g. KECCAK256_NULL_S for string representation of Keccak-256 hash of null)

// ./examples/constants.ts

import { BIGINT_2EXP96, KECCAK256_NULL_S } from '@ethereumjs/util'

console.log(`The keccak-256 hash of null: ${KECCAK256_NULL_S}`)
console.log(`BigInt constants (performance), e.g. BIGINT_2EXP96: ${BIGINT_2EXP96}`)

DB interface for database abstraction (Blockchain, Trie), see e.g. @ethereumjs/trie recipes) for usage.

Genesis related interfaces and helpers.

Internalized simple helper methods like isHexString. Note that methods from this module might get deprecated in the future.

KZG interface (used for 4844 blob txs), see @ethereumjs/tx README for main usage instructions.

Simple map DB implementation using the DB interface (see above).

Module with a compact generic request class for EIP-7685 general purpose execution layer requests to the CL (Prague hardfork) with the possibility to set data and a type conforming to the following request types:

• EIP-6110: DepositRequest (Prague Hardfork)
• EIP-7002: WithdrawalRequest (Prague Hardfork)
• EIP-7251: ConsolidationRequest (Prague Hardfork)

These request types are mainly used within the @ethereumjs/block library where applied usage instructions are provided in the README.

Small helpers around signature validation, conversion, recovery as well as selected convenience wrappers for calls to the underlying crypo libraries, using the cryptographic primitive implementations from the Noble crypto library set. If possible for your use case it is recommended to use the underlying crypto libraries directly for robustness.

// ./examples/signature.ts

import { bytesToHex, ecrecover, hexToBytes } from '@ethereumjs/util'

const chainId = BigInt(3) // Ropsten

const ecHash = hexToBytes('0x82ff40c0a986c6a5cfad4ddf4c3aa6996f1a7837f9c398e17e5de5cbd5a12b28')
const r = hexToBytes('0x99e71a99cb2270b8cac5254f9e99b6210c6c10224a1579cf389ef88b20a1abe9')
const s = hexToBytes('0x129ff05af364204442bdb53ab6f18a99ab48acc9326fa689f228040429e3ca66')
const v = BigInt(41)

const pubkey = ecrecover(ecHash, v, r, s, chainId)

console.log(`Recovered public key ${bytesToHex(pubkey)} from valid signature values`)

Various TypeScript types. Direct usage is not recommended, type structure might change in the future.

Various functions for accessing verkle state:

// ./examples/verkle.ts

import {
  VerkleLeafType,
  bytesToHex,
  decodeVerkleLeafBasicData,
  getVerkleKey,
  hexToBytes,
} from '@ethereumjs/util'

const state = {
  '0xdf67dea9181141d6255ac05c7ada5a590fb30a375023f16c31223f067319e300':
    '0x0100000001000000000000000000000001000000000000000000000000000000',
  '0xdf67dea9181141d6255ac05c7ada5a590fb30a375023f16c31223f067319e301':
    '0x923672e5275a0104000000000000000000000000000000000000000000000000',
  '0xdf67dea9181141d6255ac05c7ada5a590fb30a375023f16c31223f067319e302':
    '0x2c01000000000000000000000000000000000000000000000000000000000000',
  '0xdf67dea9181141d6255ac05c7ada5a590fb30a375023f16c31223f067319e303':
    '0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470',
  '0xdf67dea9181141d6255ac05c7ada5a590fb30a375023f16c31223f067319e304': null,
}

const stem = hexToBytes('0xdf67dea9181141d6255ac05c7ada5a590fb30a375023f16c31223f067319e3')

const basicDataKey = getVerkleKey(stem, VerkleLeafType.BasicData)
const basicDataRaw = state[bytesToHex(basicDataKey)]
const basicData = decodeVerkleLeafBasicData(hexToBytes(basicDataRaw!))

console.log(basicData) // { version: 1, nonce: 1n, codeSize: 0, balance: 1n }

Class representing an EIP-4895 Withdrawal with different constructors as well as conversion and output helpers.

// ./examples/withdrawal.ts

import { createWithdrawal } from '@ethereumjs/util'

const withdrawal = createWithdrawal({
  index: 0n,
  validatorIndex: 65535n,
  address: '0x0000000000000000000000000000000000000000',
  amount: 0n,
})

console.log('Withdrawal object created:')
console.log(withdrawal.toJSON())

We provide hybrid ESM/CJS builds for all our libraries. With the v10 breaking release round from Spring 2025, all libraries are "pure-JS" by default and we have eliminated all hard-wired WASM code. Additionally we have substantially lowered the bundle sizes, reduced the number of dependencies, and cut out all usages of Node.js-specific primitives (like the Node.js event emitter).

It is easily possible to run a browser build of one of the EthereumJS libraries within a modern browser using the provided ESM build. For a setup example see ./examples/browser.html.

Read the API docs.

With the breaking releases from Summer 2023 we have started to ship our libraries with both CommonJS (cjs folder) and ESM builds (esm folder), see package.json for the detailed setup.

If you use an ES6-style import in your code files from the ESM build will be used:

import { EthereumJSClass } from '@ethereumjs/[PACKAGE_NAME]'

If you use Node.js specific require, the CJS build will be used:

const { EthereumJSClass } = require('@ethereumjs/[PACKAGE_NAME]')

Using ESM will give you additional advantages over CJS beyond browser usage like static code analysis / Tree Shaking which CJS can not provide.

The following methods are available by an internalized version of the ethjs-util package (MIT license), see internal.ts. The original package is not maintained any more and the original functionality will be replaced by own implementations over time (starting with the v7.1.3 release, October 2021).

• arrayContainsArray
• getBinarySize
• stripHexPrefix
• isHexString
• isHexString
• padToEven
• fromAscii
• fromUtf8
• toUtf8
• toAscii
• getKeys

They can be imported by name:

import { stripHexPrefix } from '@ethereumjs/util'

See our organizational documentation for an introduction to EthereumJS as well as information on current standards and best practices. If you want to join for work or carry out improvements on the libraries, please review our contribution guidelines first.

MPL-2.0