Flashbots

Flashbots is a research and development organization that builds infrastructure to mitigate the negative externalities of Maximal Extractable Value (MEV) on Ethereum and other blockchains. Its primary goal is to bring transparency, fairness, and efficiency to the extraction of MEV—the profit validators or miners can make by including, excluding, or reordering transactions within a block. The organization is best known for creating the Flashbots Auction, a private communication channel (a "dark pool") that allows searchers to submit complex transaction bundles directly to block producers, bypassing the public mempool.

The core innovation, MEV-Boost, is middleware that enables Ethereum validators to outsource block building to a competitive marketplace of specialized builders after The Merge. This separates the roles of block proposer and block builder, creating a more efficient and decentralized market. Builders compete to create the most profitable blocks by including MEV opportunities, and proposers simply choose the most valuable header. This system democratizes access to MEV profits, distributes them more widely among validators, and crucially, prevents the harmful network congestion and failed transaction frontrunning that occurred when MEV extraction happened in the public mempool.

Flashbots' ecosystem comprises several key actors: Searchers who run algorithms to detect MEV opportunities, Builders who construct full blocks from these opportunities and user transactions, and Relays that act as trusted intermediaries to ensure block validity before delivery to proposers. The organization also maintains SUAVE (Single Unified Auction for Value Expression), a decentralized block builder and cross-chain MEV market that aims to decentralize the block building process itself. By providing these open-source tools, Flashbots aims to neutralize the centralizing forces and user-experience degradation inherent in uncontrolled MEV extraction.

The term Flashbots is a portmanteau, combining 'flash'—referring to the high-speed, near-instantaneous nature of the transactions it facilitates—and 'bots'—denoting the automated software agents that execute these strategies. It was coined in 2020 by a research collective led by Phil Daian, Stephane Gosselin, and others to describe their proposed solution to the problems of Maximal Extractable Value (MEV) and transaction frontrunning on Ethereum. The name directly reflects the project's initial focus: creating a private communication channel, or 'dark pool,' for searchers (who run sophisticated bots) to communicate transaction bundles to miners without revealing their strategies to the public mempool.

Conceptually, Flashbots originated from academic and industry research into MEV, a concept formalized in the 2019 paper 'Flash Boys 2.0.' This paper drew an analogy between high-frequency trading in traditional finance (popularized by Michael Lewis's book Flash Boys) and the emerging extractive strategies on blockchains. The Flashbots project was founded to mitigate the negative externalities of MEV, such as network congestion and failed transactions, by bringing order flow off-chain. Its creation marked a pivotal shift from viewing MEV as an unavoidable byproduct to treating it as a manageable resource that could be allocated efficiently and transparently.

The project's evolution is embedded in its nomenclature. The core component, Flashbots Relay, acts as the intermediary. The MEV-Boost software, a later and critical development, extends the Flashbots ethos to Ethereum's post-Merge Proof-of-Stake ecosystem, allowing validators to outsource block building to a competitive market of builders. Thus, the term 'Flashbots' has grown from describing a specific research initiative and its associated bots to encompassing a broader ecosystem and suite of tools designed to democratize access to MEV and preserve the neutrality of the base chain.

Flashbots operates through a permissionless, transparent network that separates block proposal from block construction. Validators (or their chosen relay operators) connect to the Flashbots Relay, which receives full blocks from a competitive ecosystem of searchers and builders. These builders construct blocks by bundling user transactions with arbitrage, liquidation, and other MEV opportunities identified by searchers. The relay then validates these blocks and presents the most profitable, valid one to the validator for signing and proposing to the network. This process occurs via a private channel, preventing frontrunning and ensuring transaction privacy until the block is published.

The system is built on three core roles: the searcher, who identifies and simulates profitable MEV opportunities; the builder, a specialized node that constructs complete, revenue-maximizing blocks by aggregating these opportunities with regular transactions; and the relay, a trusted intermediary that receives blocks from builders, validates their correctness (e.g., pays the validator, is structurally sound), and relays the most profitable valid block to the validator. This architecture creates a competitive marketplace where builders bid for block space, with profits shared between the builder and the proposing validator, a concept known as MEV smoothing.

A key innovation is the use of a commit-reveal scheme for block submission. Builders send a commitment to the relay, which only reveals the full block content after the validator has signed a header for it. This prevents other network participants from stealing the profitable bundle of transactions. Furthermore, the system enforces credible neutrality; the relay does not censor transactions based on content but only on validity and profitability. This design directly addresses the dark forest problem of decentralized finance, where unprotected MEV transactions were vulnerable to predatory bots.

For users and applications, Flashbots provides the RPC endpoint eth_sendBundle and later the SUAVE-oriented architecture, allowing them to submit transaction bundles directly. These bundles are atomic—all transactions succeed or fail together—protecting against failed arbitrage attempts. By creating a transparent, auction-based market for block space, Flashbots aims to democratize access to MEV, reduce network congestion caused by failed arbitrage transactions, and redistribute a portion of extracted value back to validators and, by extension, to ETH stakers through increased staking rewards.

The long-term vision extends beyond the initial relay model with SUAVE (Single Unifying Auction for Value Expression). SUAVE is a decentralized, blockchain-agnostic mempool and decentralized block builder network intended to become a preferred execution environment for multiple chains. It aims to further decentralize the block building market, enhance cross-chain MEV opportunities, and provide users with more control over their transaction execution, ultimately seeking to make MEV benefits more transparent and widely distributed across the ecosystem.

Flashbots is a research and development organization founded to address the risks and centralization pressures posed by Maximal Extractable Value (MEV) on the Ethereum blockchain. Its core contribution is the Flashbots Auction, a sealed-bid, first-price auction mechanism that allows block builders to communicate transaction bundles—including frontrunning and backrunning strategies—directly to validators (then miners) via a private, off-chain channel known as a relay. This system, often called MEV-geth, created a transparent marketplace for MEV, moving potentially harmful competition off the public mempool and reducing network congestion from failed arbitrage transactions.

The primary infrastructure components introduced by Flashbots are the relay and the builder. The relay is a trusted, neutral server that receives transaction bundles from searchers and builders and forwards the most profitable, valid block to validators. Builders are specialized nodes that construct entire block templates by aggregating bundles from searchers, who are bots scanning for MEV opportunities. This separation of roles established a proposer-builder separation (PBS) model in practice, long before its formal protocol integration. The system's success was measured by its reduction of gas price wars and the democratization of access to MEV extraction.

Following Ethereum's transition to Proof-of-Stake, Flashbots' architecture evolved into MEV-Boost, a middleware that allows Ethereum validators (proposers) to outsource block construction to a competitive market of builders via multiple relays. This preserved the benefits of the auction model in a post-merge environment and became widely adopted, with a majority of Ethereum blocks being built through this system. Flashbots' work has fundamentally shaped the MEV supply chain, introducing concepts like transaction ordering as a service and highlighting the critical need for in-protocol solutions to mitigate MEV's long-term risks.

The research and operational insights gained from running the Flashbots Auction and MEV-Boost directly informed the design of SUAVE (Single Unifying Auction for Value Expression), Flashbots' ambitious vision for a decentralized, chain-agnostic future for MEV. SUAVE aims to decentralize every layer of the MEV supply chain—including preference expression, block building, and execution—by creating a separate blockchain and mempool specialized for these functions. This represents the logical evolution of Flashbots' mission: from creating a centralized, practical solution to sketching the blueprint for a fully decentralized one.