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The ERC-4337 standard, also known as EIP-4337, allows developers to achieve account abstraction on the Polygon PoS. This page provides a simplified overview of the different components of ERC-4337 and how they work together.

The ERC-4337 standard consists of four main components: UserOperation, Bundler, EntryPoint, and Contract Account. Optional components include Paymasters and Aggregators.

Building ERC-4337 transactions

ERC-4337 transactions are called UserOperations to avoid confusion with the regular transaction type. UserOperations are pseudo-transaction objects that are used to execute transactions with contract accounts. ERC-4337 transactions have to be sent to nodes that include ERC-4337 bundlers.

The UserOperation object has a few fields.

Field Type Description
sender address The address of the smart contract account
nonce uint256 Anti-replay protection
initCode bytes Code used to deploy the account if not yet on-chain
callData bytes Data that’s passed to the sender for execution
callGasLimit uint256 Gas limit for execution phase
verificationGasLimit uint256 Gas limit for verification phase
preVerificationGas uint256 Gas to compensate the bundler
maxFeePerGas uint256 Similar to EIP-1559 max fee
maxPriorityFeePerGas uint256 Similar to EIP-1559 priority fee
paymasterAndData bytes Paymaster Contract address and any extra data required for verification and execution
signature bytes Used to validate a UserOperation along with the nonce during verification

ERC-4337 wallets

Users must have an ERC-4337 smart contract account to validate UserOperations. The core interface for an ERC-4337 wallet is:

interface IAccount {
  function validateUserOp
      (UserOperation calldata userOp, bytes32 userOpHash, address aggregator, uint256 missingAccountFunds)
      external returns (uint256 sigTimeRange);


  • ERC-4337 proposal is the link to the official proposal and technical specification.
  • @account-abstraction SDK is an npm package for using ERC-4337 developed by the authors of the proposal.
  • Stackup provides node services with ERC-4337 bundlers and other ERC-4337 infrastructure.
  • WalletKit is an all-in-one platform for adding smart, gasless wallets to your app. It has integrated support for ERC-4337 and comes with a paymaster and bundler included, requiring no extra setup.