MEVBoost

MEV-Boost is an off-chain relay protocol that enables maximal extractable value (MEV) extraction in Ethereum’s proof-of-stake system by decoupling block production from the consensus layer. Developed by Flashbots, it creates a competitive market of block builders and relays, allowing validators to source blocks from multiple independent parties rather than relying on a single proposer.

Operation: Independent builders search for MEV opportunities and assemble candidate blocks in which transactions are ordered to maximize value. Builders publish these blocks to a network of relays, which broadcast them to participating validators. For each slot, validators pull the best available blocks from their connected relays and decide which one to include in the beacon chain.

Mechanics: Each block carries an execution payload and is signed by the builder. Relays forward candidate blocks to validators, who retain final authority to approve or reject them. MEV-Boost does not alter consensus rules; it merely supplies blocks for consideration and unlocks competition among builders and relay operators.

History and impact: The protocol was introduced by Flashbots and integrated into Ethereum’s post-merge ecosystem to foster decentralization of MEV opportunities and reduce reliance on any single proposer. Over time, MEV-Boost adoption has grown, with many validators using multiple relays to diversify block sources.

Risks and criticisms: Delegating block production to third parties introduces new attack surfaces, including relay or builder censorship, MEV fragmentation, and potential centralization if a small number of relay operators gain influence. Users should assess trust, security practices, and governance when participating in the MEV-Boost network.