What is Flashbots?
Flashbots is a research and development organization that built infrastructure to address the negative effects of MEV (Maximal Extractable Value) on Ethereum. Their core innovation is a private transaction relay system that separates MEV extraction from the public mempool, reducing network congestion and protecting users from sandwich attacks.
Before Flashbots, MEV bots competed by bidding up gas prices in “priority gas auctions,” clogging the network. Flashbots created a more efficient system where MEV searchers submit transaction bundles directly to block builders.
The Flashbots Stack
Searchers
MEV bots (searchers) look for profitable opportunities — arbitrage, liquidation, sandwich attacks. Instead of sending transactions to the public mempool, they bundle them and send to block builders via the Flashbots relay.
Block Builders
Specialized entities that construct optimized blocks by including the most profitable transaction bundles from searchers. Builders compete to create the most valuable block.
Block Proposers (Validators)
Validators propose blocks to the network. Instead of building blocks themselves, they select the most profitable block from builders via MEV-Boost (a PoS upgrade to Flashbots).
The Relay
The Flashbots relay connects builders to proposers. It ensures builders’ blocks are delivered to validators without revealing the block contents prematurely (preventing MEV theft).
Flashbots Protect
Flashbots Protect is a free RPC service for regular users:
- Transactions are sent to the private mempool, not the public one
- MEV bots cannot see or sandwich-attack your transactions
- If a transaction isn’t included within 25 blocks, it’s automatically cancelled
- You still pay normal gas fees — no premium for protection
To use Flashbots Protect, simply set your wallet’s RPC to the Flashbots Protect endpoint.
Frequently Asked Questions
Q: Does Flashbots eliminate MEV? A: No. Flashbots doesn’t eliminate MEV — it makes the extraction more efficient and less harmful. Arbitrage and liquidations still happen; they’re just routed through a private system instead of clogging the public network.
Q: Is Flashbots Protect free? A: Yes. Flashbots Protect is free for end users. The economics work because searchers pay builders for inclusion, and builders share revenue with validators.
Q: Is Flashbots decentralized? A: Flashbots is actively working toward decentralization. The current relay has some centralization concerns (it’s a trusted intermediary between builders and validators). Projects like SUAVE aim to further decentralize the MEV supply chain.