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Private Transactions

How to send a single transaction to Flashbots‚Äč

If you want to send a single transaction to Flashbots without sending it as a bundle, you can use the eth_sendPrivateTransaction method.

This method sends your transaction to the Flashbots builder on every block for a maximum of 25 blocks. No need to listen for the next block and re-send yourself.

Private transactions can be cancelled with the eth_cancelPrivateTransaction method. Once a transaction is included in a block and received by proposers, we cannot "recall" it. However, we can stop including transactions in future blocks.

See RPC endpoint for JSON-RPC definitions of the methods.

These methods are currently implemented in ethers-provider-flashbots-bundle.js and web3-flashbots.py.

const signer = Wallet.createRandom()
const provider = new providers.JsonRpcProvider("http://localhost:8545")
const flashbotsProvider = await FlashbotsBundleProvider.create(provider, signer)

const transaction = {
from: signer.address,
to: signer.address,
value: "0x42",
gasPrice: BigNumber.from(99).mul(1e9),
gasLimit: BigNumber.from(21000),
}

const res = await flashbotsProvider.sendPrivateTransaction({
transaction,
signer,
}, {
maxBlockNumber: (await provider.getBlockNumber()) + 5, // only allow tx to be included for the next 5 blocks
});

const waitRes = await res.wait();
if (waitRes === FlashbotsTransactionResolution.TransactionIncluded) {
console.log("Private transaction successfully included on-chain.")
} else if (waitRes === FlashbotsTransactionResolution.TransactionDropped) {
console.log("Private transaction was not included in a block and has been removed from the system.")
}