# Bundler API — Hanzo AI

> Production-grade bundler for account abstraction.

Available Now

# Bundler API

ERC-4337 UserOperation bundling service

Production-grade bundler for account abstraction. Submit, simulate, and track UserOperations across all ERC-4337 compatible chains with reliable transaction inclusion.

### UserOp Bundling

Efficiently bundle multiple UserOperations into single transactions.

### Fast Inclusion

Priority transaction submission for quick block inclusion.

### Simulation

Pre-flight simulation to validate operations before submission.

### Multi-chain Support

ERC-4337 bundling across Ethereum, Polygon, Arbitrum, and more.

[Back to Web3 Overview](https://hanzo.ai/blockchain)

## Get Your API Key

Start building in under 5 minutes

HA

Failover

<50ms

Latency

100+

Chains

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No credit card required. Free tier includes 300M compute units/month.

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## Key Capabilities

Everything you need, nothing you don&#x27;t.

### UserOp Bundling

Efficiently bundle multiple UserOperations into single transactions.

### Fast Inclusion

Priority transaction submission for quick block inclusion.

### Simulation

Pre-flight simulation to validate operations before submission.

### Multi-chain Support

ERC-4337 bundling across Ethereum, Polygon, Arbitrum, and more.

### Auto-retry

Automatic retry with gas price adjustment for stuck operations.

### Status Tracking

Real-time status updates from submission to confirmation.

### Operation History

Query past UserOperations and their execution results.

### Custom Mempools

Support for alternative mempools and private submission.

### Analytics

Track success rates, gas usage, and operation metrics.

## Simple to Integrate

Get started with just a few lines of code. SDKs for every language.

Solidity

Node

Python

Go

Rust

C

C++

Ruby

UserOpBuilder.sol

```
// SPDX-License-Identifier: MIT pragma solidity ^0.8.24; import "@account-abstraction/contracts/interfaces/IEntryPoint.sol"; import "@account-abstraction/contracts/interfaces/UserOperation.sol"; contract UserOpHelper { IEntryPoint public immutable entryPoint; constructor(address _entryPoint) { entryPoint = IEntryPoint(_entryPoint); } // Encode a simple ETH transfer for UserOp callData function encodeTransfer(address to, uint256 value) external pure returns (bytes memory) { return abi.encodeWithSignature("execute(address,uint256,bytes)", to, value, ""); } // Encode ERC20 transfer for UserOp callData function encodeERC20Transfer( address token, address to, uint256 amount ) external pure returns (bytes memory) { bytes memory tokenCall = abi.encodeWithSignature("transfer(address,uint256)", to, amount); return abi.encodeWithSignature("execute(address,uint256,bytes)", token, 0, tokenCall); } // Encode batch execution for UserOp callData function encodeBatch( address[] calldata targets, uint256[] calldata values, bytes[] calldata datas ) external pure returns (bytes memory) { return abi.encodeWithSignature( "executeBatch(address[],uint256[],bytes[])", targets, values, datas ); } // Get gas limits for simulation function estimateGas(UserOperation calldata userOp) external returns ( uint256 preVerificationGas, uint256 verificationGasLimit, uint256 callGasLimit ) { // Simulate execution to estimate gas try entryPoint.simulateValidation(userOp) {} catch (bytes memory result) { // Parse simulation result for gas estimates } } // Get current nonce for account function getNonce(address account) external view returns (uint256) { return entryPoint.getNonce(account, 0); } }
```

## Built For

### Smart Wallet Apps

Power account abstraction wallets with reliable bundling.

### Gasless Transactions

Enable sponsored transactions with paymaster integration.

### Batch Operations

Execute multiple actions in a single user signature.

### Session Keys

Support for temporary permissions and automated actions.

## Supported Chains

EthereumPolygonArbitrumOptimismBaseBNB ChainAvalanchezkSyncLinea

## Start Building with Bundler API

Get your free API key and ship your first request in under 5 minutes. No credit card required.

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## Get Bundler API

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