Bundler

The Openfort Bundler is a high-performance ERC-4337 bundler that aggregates UserOperations and submits them to the blockchain. It's designed for reliability and speed, ensuring your users' transactions are included quickly.

Overview

ERC-4337 bundlers are specialized relayers that:

Receive UserOperations from applications
Validate and simulate operations
Bundle multiple operations into transactions
Submit them to the blockchain via the EntryPoint contract

The bundler handles all this complexity, providing a JSON-RPC interface for your application.

Getting Started

To use the bundler, make JSON-RPC requests to:

https://api.openfort.io/rpc/{chainId}

Replace {chainId} with the appropriate chain ID. Include your Openfort publishable key in the Authorization header:

Authorization: Bearer YOUR_OPENFORT_PUBLISHABLE_KEY

Get your public key from the Openfort Dashboard.

Available Endpoints

Method	Description
`eth_sendUserOperation`	Submit a UserOperation for inclusion
`eth_estimateUserOperationGas`	Estimate gas for a UserOperation
`eth_getUserOperationReceipt`	Get the receipt for a submitted operation
`eth_getUserOperationByHash`	Retrieve a UserOperation by its hash
`eth_supportedEntryPoints`	List supported EntryPoint contracts

Quick Example

This example shows how to use the Openfort bundler with viem to send a sponsored UserOperation:

import { createPublicClient, http } from 'viem'
import { sepolia } from 'viem/chains'
import { privateKeyToAccount } from 'viem/accounts'
import {
  createBundlerClient,
  createPaymasterClient,
  toCoinbaseSmartAccount
} from 'viem/account-abstraction'
 
// Create a public client for reading blockchain state
const client = createPublicClient({
  chain: sepolia,
  transport: http(),
})
 
// Create the paymaster client with Openfort
const paymasterClient = createPaymasterClient({
  transport: http('https://api.openfort.io/rpc/11155111', {
    fetchOptions: {
      headers: {
        'Authorization': 'Bearer YOUR_OPENFORT_PUBLISHABLE_KEY',
      },
    },
  }),
})
 
// Create a smart account (using Coinbase Smart Account as an example)
const owner = privateKeyToAccount(process.env.PRIVATE_KEY)
const account = await toCoinbaseSmartAccount({
  client,
  owners: [owner],
  version: '1.1',
})
 
// Create the bundler client with the Openfort bundler
const bundlerClient = createBundlerClient({
  account,
  paymaster: paymasterClient,
  client,
  paymasterContext: {
    policyId: 'YOUR_POLICY_ID_HERE'
  },
  transport: http('https://api.openfort.io/rpc/11155111', {
    fetchOptions: {
      headers: {
        'Authorization': 'Bearer YOUR_OPENFORT_PUBLISHABLE_KEY',
      },
    },
  }),
})
 
// Send a UserOperation
const hash = await bundlerClient.sendUserOperation({
  calls: [{
    to: '0xcb98643b8786950F0461f3B0edf99D88F274574D',
    value: 0n,
    data: '0x1234',
  }],
})
 
// Wait for the UserOperation receipt
const receipt = await bundlerClient.waitForUserOperationReceipt({ hash })
console.log('UserOperationReceipt:', receipt)

Next Steps

Endpoint Reference - Detailed documentation for all bundler methods
Error Reference - Common errors and how to resolve them
Supported Chains - List of networks where the bundler is available