@pulsadev/flashbots

Flashbots bundle builder — private transactions, MEV protection, bundle simulation, MEV-Share. Zero dependencies.

Send transactions privately, build MEV bundles, simulate execution. No ethers, no viem required.

Features

• Private transactions — send via Flashbots Protect, MEV Blocker, or any builder
• Bundle submission — eth_sendBundle with multiple txs, atomic execution
• Bundle simulation — eth_callBundle to preview results before submission
• Bundle stats — flashbots_getBundleStatsV2 for tracking
• MEV-Share — mev_sendBundle for MEV revenue sharing
• Cancel private tx — cancel pending private transactions
• Built-in builder registry — Flashbots, Titan, rsync, MEV Blocker
• Zero dependencies — ~7 KB bundled, ESM + CJS, pure TypeScript

Install

npm install @pulsadev/flashbots

Quick Start

Send private transaction (MEV protected)

import { sendProtectedTransaction } from '@pulsadev/flashbots'

const txHash = await sendProtectedTransaction(signedTx)
// Sent via Flashbots Protect — not visible in public mempool

Send bundle

import { createBundle, sendBundle, simulateBundle } from '@pulsadev/flashbots'

const bundle = createBundle(
  [signedTx1, signedTx2],
  targetBlockNumber,
)

// Simulate first
const sim = await simulateBundle(bundle, currentBlock)
if (sim.success) {
  const result = await sendBundle(bundle)
  console.log('Bundle hash:', result.bundleHash)
}

MEV-Share bundle

import { createMevShareBundle, sendMevShareBundle } from '@pulsadev/flashbots'

const bundle = createMevShareBundle([signedTx], blockNumber, blockNumber + 5n)
const result = await sendMevShareBundle(bundle)

Use different builders

import { sendBundle, getBuilders, getBundleRelays } from '@pulsadev/flashbots'

const relays = getBundleRelays(1) // All Ethereum bundle relays
for (const relay of relays) {
  await sendBundle(bundle, relay.rpcUrl) // Send to all builders
}

API

Transactions

| Function | Description | |----------|-------------| | sendProtectedTransaction(signedTx, rpcUrl?) | Send via Flashbots Protect RPC | | sendPrivateTransaction(signedTx, options?, rpcUrl?) | Send private tx with options | | cancelPrivateTransaction(txHash, rpcUrl?) | Cancel pending private tx |

Bundles

| Function | Description | |----------|-------------| | createBundle(txs, blockNumber, options?) | Create a bundle | | sendBundle(bundle, relayUrl?) | Submit bundle to relay | | simulateBundle(bundle, stateBlock, relayUrl?) | Simulate bundle execution | | getBundleStats(bundleHash, blockNumber, relayUrl?) | Get bundle status |

MEV-Share

| Function | Description | |----------|-------------| | createMevShareBundle(txs, block, maxBlock?) | Create MEV-Share bundle | | sendMevShareBundle(bundle, relayUrl?) | Submit to MEV-Share |

Builder Registry

| Function | Description | |----------|-------------| | getBuilders(chainId) | All builders for a chain | | getBundleRelays(chainId) | Bundle-supporting relays | | getPrivateTxRelays(chainId) | Private tx relays | | getProtectRpc(chainId) | Flashbots Protect RPC URL |

License

MIT © Yuto Nakamura