What is ERC-4337?

Written by Alchemy

Published on January 6, 20267 min read

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What is ERC-4337?

ERC-4337 is the foundational standard that enables Account Abstraction on Ethereum without requiring any protocol changes. As the backbone of smart wallet infrastructure, ERC-4337 allows you to use smart contract wallets with programmable verification logic instead of traditional externally owned accounts (EOAs) as your primary account.

Since launching on Ethereum mainnet on March 1st, 2023, ERC-4337 has transformed how developers build wallet experiences. Over 40 million smart accounts have been deployed across Ethereum and Layer 2 networks, with nearly 20 million deployed in 2024 alone. The standard has enabled over 100 million UserOperations, marking a tenfold increase from 2023.

Why ERC-4337 Matters for Developers

ERC-4337 runs on top of the blockchain and does not require any changes to the blockchain itself. This architecture makes it usable today on Ethereum or any EVM chain without significant changes to the underlying blockchain infrastructure.

The key innovation of ERC-4337 is introducing a higher-layer infrastructure for account abstraction that preserves Ethereum's decentralization and censorship resistance. Unlike previous proposals that required consensus-layer changes, ERC-4337 uses an alternative mempool and bundler ecosystem to achieve account abstraction today.

Core Concepts: How ERC-4337 Works

Understanding ERC-4337 requires grasping six fundamental concepts that work together to enable smart contract wallets: UserOperation, Bundler, EntryPoint, Paymaster, Sender, and Aggregator.

UserOperation: The Pseudo-Transaction Object

A UserOperation is a pseudo-transaction object representing your transaction intent. Unlike traditional transactions, UserOperations include additional fields and use an alternate mempool with programmable authentication instead of single private key signatures.

Any UserOperation can contain multiple instructions and additional data to execute smart contract calls initiated by the Smart Contract Account. UserOperations begin the ERC-4337 transaction flow.

What makes UserOperations different from traditional transactions?

• Additional fields: UserOperations include new fields in the transaction structure for EntryPoint, Bundler, and Aggregator addresses

• Alternate mempool: UserOperations are sent to a separate mempool where bundlers package them

• Programmable authentication: Instead of fixed ECDSA signatures, authentication is programmable

Bundler: The Infrastructure Layer

A bundler monitors the alternative mempool specifically built for UserOperations. The bundler bundles multiple UserOperations into a single transaction and submits that transaction to the EntryPoint contract. Bundlers are compensated for this service by taking a portion of the gas fees.

Bundlers are critical infrastructure for ERC-4337 because all Ethereum transactions need to be initiated by an Externally Owned Account (EOA). Bundlers have EOAs, and in an account abstracted ecosystem, they are the only participants that need EOAs, thereby removing the requirement for users to own an EOA wallet.

EntryPoint: The Verification and Execution Contract

The EntryPoint is a singleton smart contract that receives transactions from bundlers, then verifies and executes UserOperations. This is the trust point for all ERC-4337 operations.

How does EntryPoint verification work?

The smart contract account defines its own verification and authentication logic. During the verification process, the EntryPoint contract checks whether the wallet has enough funds to pay the maximum amount of gas it might use, based on the gas fields in the UserOperation. If the wallet lacks sufficient funds, the EntryPoint contract rejects the transaction.

How does EntryPoint execution work?

During the execution process, the EntryPoint contract executes the UserOperation by calling the account using the calldata specified, and taking money from the Smart Contract Account to reimburse the Bundler with the right amount of ETH to pay for gas.

Paymaster: Flexible Gas Payment Policies

The Paymaster is an ERC-4337 defined smart contract that handles the implementation of gas payment policies. These gas policies create flexibility for how gas is paid (in what currency) and by whom, removing the prerequisite for users to hold native blockchain tokens to interact with the blockchain.

For example, instead of paying gas for Ethereum transactions in ETH, users can pay for gas fees with any ERC-20 token like USDC or USDT.

What can developers do with Paymasters?

• Sponsor gas fees for their users

• Enable gas payments in stablecoins like USDC

• Enable gas payments in other ERC-20 tokens

• Create custom gas policies for their applications

Alchemy's gasless transaction infrastructure realizes the benefits of ERC-4337 defined Paymasters by completely abstracting away gas payments from users while letting the application decide what that abstraction should be.

Aggregator: Signature Optimization

An Aggregator is a smart contract that implements a signature scheme supporting aggregation—a contract that can verify aggregated signatures.

If multiple messages are signed with different keys, a single combined signature can be generated that verifies all constituent signatures. By combining multiple signatures into a single signature, aggregators help save on calldata costs, with multiple bundled UserOperations validated in a single step.

ERC-4337 Adoption and Growth

Since launching in March 2023, ERC-4337 has evolved from an experimental standard to production-ready infrastructure powering millions of smart accounts across Ethereum and Layer 2 networks.

The ecosystem experienced a significant inflection point in 2024, with adoption accelerating across key metrics. By year-end 2024, the standard had facilitated over 100 million UserOperations—a tenfold increase from 2023. Nearly 20 million ERC-4337 native smart accounts were deployed in 2024 alone, demonstrating 7x year-over-year growth.

Current adoption trends show continued momentum:

• Network distribution: Base, Polygon, and Optimism lead ERC-4337 adoption, with Base seeing particularly strong growth following infrastructure support launch

• Gas sponsorship: The vast majority of UserOperations leverage paymasters, with tens of millions of dollars in gas fees sponsored by applications

• Use case expansion: Beyond wallet infrastructure, ERC-4337 is powering gaming, decentralized social networks, DeFi applications, and NFT platforms

With EIP-7702 integration following the May 2025 Pectra upgrade, the account abstraction ecosystem is positioned for further acceleration. Industry projections anticipated over 200 million smart accounts by late 2025, with the combination of ERC-4337 and EIP-7702 creating new pathways for adoption.

The Evolution: ERC-6900 and EIP-7702

The ERC-4337 ecosystem continues to evolve with complementary standards that enhance account abstraction:

ERC-6900: Modular Smart Account Standard

ERC-6900 is another approach to modular smart accounts, developed by Alchemy, Circle, Quantstamp, and Ethereum Foundation contributors. Proposed in 2023, ERC-6900 takes a more opinionated approach to account modularity compared to minimalist alternatives.

ERC-6900 defines standards for plugin management, execution functions, and validation hooks within smart accounts. While ERC-6900 provides a comprehensive framework for modular accounts, some developers have found it limiting for advanced functions like off-chain module toggling and signature aggregators, leading to adoption of alternative minimalist standards.

EIP-7702: Extending EOAs with Smart Account Features

EIP-7702, introduced with Ethereum's Pectra upgrade on May 7, 2025, allows Externally Owned Accounts to temporarily execute smart contract code. This brings account abstraction features like batch transactions and sponsored gas to existing EOA addresses without requiring users to deploy new smart wallets.

EIP-7702 is complementary to ERC-4337—not a replacement. Wallets can implement EIP-7702 and leverage existing ERC-4337 infrastructure including bundlers and paymasters. Major wallets like Ambire and Trust Wallet have already rolled out support for EIP-7702.

How EIP-2938 and EIP-3074 Informed ERC-4337

ERC-4337 builds upon previous Ethereum Improvement Proposals. EIP-2938 introduced the idea for enabling smart contracts to operate as a "top-level account that pays fees and starts transaction execution." EIP-3074 introduced the idea of delegating "control of the externally owned account (EOA) to a smart contract."

ERC-4337 combined these ideas with an alternative mempool implementation and a route that did not require consensus layer changes. This approach enabled deployment on Ethereum mainnet without waiting for protocol upgrades.

Real-World Applications of ERC-4337

Developers are using ERC-4337 to build significantly better user experiences:

• Gasless onboarding: Applications sponsor gas fees for new users, removing the barrier of needing ETH before interacting with the blockchain

• Gaming experiences: Players can interact with blockchain games without constantly signing transactions

• Social recovery: Users can set up trusted contacts to help recover accounts if they lose access

• Batch transactions: Multiple operations can be executed in a single UserOperation, reducing friction

• Session keys: Recurring transactions can be automated without compromising security

• Payment in stablecoins: Users can pay transaction fees in USDC or other tokens instead of ETH

Getting Started with ERC-4337

Building with ERC-4337 today is straightforward. The standard is live on Ethereum mainnet and supported across major Layer 2 networks including Arbitrum, Optimism, Base, and Polygon.

For application developers, integrating ERC-4337 means choosing a smart account implementation, connecting to bundler infrastructure, and optionally setting up paymaster policies. Major infrastructure providers like Alchemy offer complete ERC-4337 stacks with bundlers, paymasters, and gas managers.

For wallet developers, implementing ERC-4337 support means building smart contract accounts that follow the standard, particularly implementing the validateUserOp function and integrating with the EntryPoint contract.

The ERC-4337 ecosystem provides battle-tested tooling, comprehensive documentation, and a growing community of developers building the next generation of Ethereum applications. Alchemy helps you integrate confidently as the industry leader in account abstraction technology, powering over 85% of market share with $100M+ processed and 400M+ transactions. Start building and join teams like World, Coinbase, Circle, and others who use account abstraction to scale their applications to users around the globe.

Frequently Asked Questions

What is ERC-4337?

ERC-4337 is the foundational standard for Account Abstraction on Ethereum. It allows users to use smart contract wallets with programmable verification logic instead of EOAs as their primary account, without requiring changes to Ethereum's consensus layer.

Does ERC-4337 require changes to Ethereum's blockchain?

No, ERC-4337 runs on top of the blockchain and does not require any changes to the blockchain itself, making it usable today on Ethereum or any EVM chain without consensus layer modifications.

What is a UserOperation and how does it differ from a traditional transaction?

A UserOperation is a pseudo-transaction object representing your transaction intent. Unlike traditional transactions, it includes additional fields for bundlers and paymasters, uses an alternate mempool, and features programmable authentication instead of fixed private key signatures.

What role do bundlers play in ERC-4337?

Bundlers monitor the alternative mempool for UserOperations, bundle multiple operations into a single transaction, and submit that transaction to the EntryPoint contract. They're compensated through gas fees and are critical infrastructure because they're the only participants that need EOAs.

How does the EntryPoint contract work?

The EntryPoint is a singleton smart contract that receives transactions from bundlers, verifies UserOperations by checking wallet funds and authentication, then executes the operations and reimburses bundlers for gas costs.

What is a Paymaster and why is it useful?

A Paymaster is a smart contract that handles gas payment policies, allowing users to pay gas fees in ERC-20 tokens like USDC instead of native tokens like ETH, or enabling developers to sponsor gas fees entirely. This removes barriers to blockchain adoption.

What does an Aggregator do in ERC-4337?

An Aggregator combines multiple signatures into a single signature that can verify all constituent signatures, helping save on calldata costs by validating multiple bundled UserOperations in a single step.

How does ERC-4337 relate to EIP-7702?

EIP-7702 is complementary to ERC-4337. While ERC-4337 enables smart contract wallets with new addresses, EIP-7702 allows existing EOA addresses to temporarily execute smart contract code. Both can leverage the same bundler and paymaster infrastructure.

When did ERC-4337 go live on Ethereum?

ERC-4337 went live on Ethereum mainnet on March 1st, 2023, when Yoav Weiss from the Ethereum Foundation announced the first deployment of the EntryPoint contract at WalletCon in Denver.