How to Implement MEV-Boost Without Centralization Risks

Maximal Extractable Value (MEV) represents profits validators can earn by including, excluding, or reordering transactions in a block. To access this value, most Ethereum validators use MEV-Boost, an out-of-protocol marketplace. Validators outsource block building to specialized builders and receive bids via intermediaries called relays. While this increases validator rewards, it creates a critical dependency: validators must trust a small, centralized set of relay operators to deliver valid blocks and distribute payments honestly.

The centralization risk is twofold. First, a handful of major relays like Flashbots, BloXroute, and Manifold process the vast majority of blocks. If these few entities were to collude or fail, the network's liveness and censorship resistance could be compromised. Second, validators cede block proposal sovereignty; they cannot see the transactions inside the blocks they sign, relying entirely on the relay's attestation. This model contradicts Ethereum's core ethos of permissionless, trust-minimized validation.

To mitigate these risks, validators must adopt a multi-relay strategy. Instead of connecting to a single default relay, operators should configure their validator client (e.g., Prysm, Lighthouse) to use multiple, diverse relays from the Boost Relay Registry. This involves editing the validator client's configuration to include endpoints for several independent relays, ensuring no single point of failure controls their block proposals. Diversity in relay operators (geographic, client, and governance) strengthens the network.

For advanced operators, running a local relay provides the highest degree of decentralization and control. Projects like mev-boost-relay offer open-source software. Running a relay requires significant resources—including high-performance hardware, reliable internet, and a curated list of trusted builders—but it allows a validator or community to verify block contents directly and contribute to network resilience.

The future of MEV distribution is moving on-chain with PBS (Proposer-Builder Separation). Protocols like EigenLayer's eigenPBS and the native PBS outlined in Ethereum's roadmap aim to bake the relay's role directly into the consensus layer. This will reduce trust assumptions and decentralize the block-building market. Until then, validator operators play a key role by diversifying their relay connections and supporting community-run infrastructure.

The core prerequisite is running a validator client (e.g., Lighthouse, Prysm, Teku) and a beacon node that supports the Builder API. Your beacon node must be configured with the --builder flag or its equivalent, enabling it to receive blocks from external builders via MEV-Boost. Crucially, you must also run a local execution client (e.g., Geth, Nethermind, Besu). This client does not need to be actively building blocks, but it must be fully synced to validate the execution payloads of the blocks proposed by external builders, a process known as local payload validation. This is your primary defense against receiving invalid or malicious blocks.

You must then choose and configure a MEV-Boost relay. Relays are intermediaries that receive blocks from builders and forward them to validators. Your choice of relay directly impacts decentralization and censorship resistance. Avoid relying on a single relay. Instead, configure your MEV-Boost middleware to connect to multiple, reputable relays from different entities. Recommended relays include those operated by flashbots.net, bloxroute.com (the "ethical" and "regulated" endpoints), builder0x69.io, and relayoor.wtf. Diversifying your relay set mitigates the risk of a single point of failure or censorship.

The final, critical step is understanding and setting your proposer preferences. This is done via a validator-registration.json file that your validator client signs and shares with relays. The key settings are fee_recipient (the address receiving transaction priority fees) and gas_limit. You must also decide on your builder selection logic. By default, MEV-Boost selects the header with the highest bid. For greater decentralization, you can implement proposer commitments by using software like mev-commit or mev-boost-rs, which allow you to commit to including certain transactions (like OFAC-compliant ones) or to prioritize builders based on criteria beyond just profit, helping to counter centralization trends.

MEV-Boost is a software component that allows Ethereum validators (proposers) to receive blocks from a competitive marketplace of specialized block builders via intermediaries called relays. This system, an implementation of Proposer-Builder Separation (PBS), is designed to democratize access to Maximal Extractable Value (MEV). Instead of building blocks themselves, validators receive pre-built, fee-maximizing blocks from builders and simply sign them. The relay acts as a trusted, neutral party that receives blocks from builders, verifies their validity and payload, and forwards the most profitable one to the proposing validator. This outsources complex MEV extraction and optimization, increasing validator rewards.

The centralization risk in MEV-Boost stems from the validator's dependency on the relay. The relay you choose determines which builders you can access and what blocks you see. If the majority of validators use a single dominant relay, that relay becomes a central point of failure and censorship. It could theoretically censor transactions, manipulate the block auction, or go offline. Furthermore, builders themselves can become centralized, with a few entities controlling most of the block space. The goal of a decentralized implementation is to distribute trust across multiple independent relays and ensure builder diversity.

To implement MEV-Boost with minimized centralization risk, your validator client configuration is critical. Do not rely on a single relay. Configure your mev-boost client (like mev-boost or mev-rs) to connect to multiple relays from different entities. A robust setup includes at least 3-4 reputable relays, such as those operated by Flashbots, BloxRoute, Eden Network, and Ultrasound Money. This ensures redundancy if one relay fails and prevents any single relay from having exclusive influence over your proposed blocks. You can find the latest relay URLs and registration requirements on their official websites or community-maintained lists like ethstaker's relay list.

Beyond multi-relay configuration, you must critically evaluate the builders permitted by your chosen relays. Some relays operate a permissioned builder list, which can limit competition. Prefer relays that support a wide and permissionless set of builders to foster a healthy marketplace. You should also monitor the builder dominance metrics published by sites like mevboost.pics to understand market concentration. For maximum decentralization and censorship resistance, consider running your own MEV-Boost relay. While resource-intensive, this gives you full control over builder permissions and block validation logic, though it requires significant Ethereum infrastructure and expertise.

The long-term solution to relay centralization is in-protocol PBS, which would bake the proposer-builder market directly into the Ethereum consensus layer. Proposals like ePBS (enshrined PBS) aim to remove the need for trusted off-chain relays entirely, making the system more robust and trust-minimized. Until then, validators must actively manage their off-chain dependencies. Regularly audit your relay set, remove relays that show signs of instability or malicious behavior, and stay informed about new relay entrants to promote ecosystem diversity. Your configuration directly impacts network health.

MEV-Boost is a middleware service that allows Ethereum validators to outsource block building to a network of specialized builders via relays. A relay is a trusted intermediary that receives blocks from builders, validates them, and forwards the most profitable one to the validator. The primary risk in a default, single-relay setup is centralization; if that relay goes offline or censors transactions, your validator's block proposals and rewards are compromised. Configuring multiple relays diversifies this risk, ensuring proposal reliability and access to a broader market of MEV opportunities.

To begin, you must edit your MEV-Boost configuration file, typically mev-boost.yaml. The core configuration involves specifying the relays array. Each relay entry requires its unique public endpoint URL. It is crucial to select relays from different entities to avoid correlated failures. A robust setup includes at least three relays from providers like Flashbots, BloXroute, Eden Network, and Manifold. For example, a basic configuration snippet would define the relay list:

yamlCopy
relays:
  - https://0xac6e77dfe25ecd6110b8e780608cce0dab71fdd5ebea22a16c0205200f2f8e2e3ad3b71d3499c54ad14d6c21b41a37ae@boost-relay.flashbots.net
  - https://0x8b5d2e73e2a3a55c6c87b8b6eb92e0149a125c852751db1422fa951e42a09b82c142c3ea98d0d9930b056a3bc9896b8f@bloxroute.max-profit.blxrbdn.com
  - https://0xb3ee7afcf27f1f1259ac1787876318c6584ee353097a50ed84f51a1f21a323b3736f8a62ccf2354346b6f630e785c3e6@relay.edennetwork.io

After updating the configuration, restart your mev-boost service and your validator client (e.g., Lighthouse, Prysm). Verify the connections by checking the MEV-Boost logs for lines indicating successful registration with each relay, such as "msg":"connected to relay". You can also query the MEV-Boost API endpoint (usually http://localhost:18550) for eth/v1/builder/status to confirm the status of each configured relay. This setup ensures that for each block proposal, MEV-Boost will solicit bids from all connected relays and select the header with the highest value for your validator to sign.

Beyond basic configuration, operational security is key. Regularly monitor relay performance and reputation. Some relays may offer different properties, such as censorship resistance lists or specialized orderflow. You can adjust the min-bid value in your configuration to reject low-value bids, though this is generally not recommended as it can reduce overall profitability. The goal is to create a resilient, permissionless connection to the builder market. For the latest relay endpoints and their public keys, always consult the official MEV-Boost documentation to ensure you are using correct and current URLs.

This multi-relay architecture directly addresses the PBS (Proposer-Builder Separation) model's resilience goals. By distributing trust, a validator is not dependent on any single relay's uptime or integrity. If one relay is offline or returns an invalid header, MEV-Boost will seamlessly use the next best offer from another. This configuration is now considered a minimum viable practice for any serious solo staker or staking pool, as it maximizes reward potential while upholding the network's neutrality and censorship-resistant properties.

Your validator's validator_client connects to MEV-Boost via a relay—a third-party service that aggregates block-building bids from searchers. The relay you choose directly influences your rewards and the network's health. Relying on a single relay reintroduces centralization risks, including transaction censorship and single points of failure. The goal is to construct a relay list that maximizes profitability while adhering to the principles of credible neutrality and liveness. This requires evaluating relays based on multiple, objective criteria rather than just historical payout data.

Start by sourcing a list of reputable, publicly-audited relays. The community-maintained MEV-Boost Relay Monitor is the canonical resource, providing real-time data on relay performance, uptime, and compliance. For production use, you should select a minimum of 3-5 relays from this list. Key selection criteria include: - Inclusion rate: The percentage of proposed blocks that successfully include payloads. - Network latency: Proximity to your node to minimize missed attestations. - Transparency: Public commitment to censorship resistance (e.g., OFAC compliance status). - Open source: Publicly verifiable code for the relay software.

Implementation is done in your validator client's configuration. For example, in a standard prysm setup, you configure MEV-Boost flags with your chosen relay URLs. Here is a snippet for a diversified relay set using three different providers:

bashCopy
--http-mev-relay "https://0xac6e77dfe25ecd6110b8e780608cce0dab71fdd5ebea22a16c0205200f2f8e2e3ad3b71d3499c54ad14d6c21b41a37ae@boost-relay.flashbots.net" \
--http-mev-relay "https://0x9000009807ed12c1f08bf4e81c6da3ba8e3fc3d953898ce0102433094e5f22f21102ec057841fcb81978ed1ea0fa8246@builder0x69.io" \
--http-mev-relay "https://0xa7ab7a996c8584251c8f925da3170bdfd6ebc75d50f5ddc4050a6fdc77f2a3b5fce2cc750d0865e06d4eeaa6a5478f4c@bloxroute.max-profit.blxrbdn.com"

This configuration allows your validator to receive block bids from multiple sources, creating redundancy.

To automate and optimize your strategy, consider using a relay monitor and selector tool like mev-boost with its -relay-check flag or community-built solutions. These tools can periodically ping relays, check their status and latency, and dynamically adjust the active relay set. This ensures you automatically avoid relays that are offline or underperforming. For advanced operators, you can implement a weighted selection logic, prioritizing relays with higher historical inclusion rates or lower latency, though this adds complexity to your setup.

Finally, your strategy must be maintained. The relay landscape evolves: new relays launch, existing ones change policies, and performance fluctuates. Regularly review your relay set—at least once per month—against the community monitor. Remove any relay that begins censoring transactions or shows consistently poor performance. By actively managing a diversified relay portfolio, you contribute to a more resilient and neutral Ethereum network while securing optimal MEV rewards for your stake.

Relay governance determines critical parameters like fee structures, validator inclusion policies, and software upgrades. As a validator, your participation helps steer these decisions away from centralized control. Most major relays, including Ultrasound Money, Agnostic, and bloXroute, operate with some form of decentralized governance, often using token-based voting on platforms like Snapshot or Tally. Your first action should be to identify the governance mechanisms for the relays in your set.

To participate effectively, you need to acquire and delegate governance tokens. For example, the Relay Oracle network uses the $RO token for voting. You can often earn these tokens by operating a validator and using the relay's services, or acquire them on decentralized exchanges. Once you hold tokens, delegate your voting power to a representative you trust or to yourself to vote directly on proposals. This process is analogous to participating in Ethereum's consensus layer governance but focused on the MEV supply chain.

Actively review governance forums and voting portals. Key proposals might involve changing the maximum bid slippage, adjusting the minimum bid for inclusion, or upgrading to new versions of the relay software that implement features like MEV-Share. Voting against proposals that increase centralization, such as those granting excessive control to a single entity or creating unfair fee structures, is a primary way validators uphold network integrity. Your vote directly impacts the economic security and censorship-resistance of Ethereum block production.

For developers, contributing to relay governance can extend to code. Many relay projects are open-source. You can audit proposed smart contract upgrades on GitHub, submit bug reports, or even contribute to the client software itself. Engaging at this technical level provides the highest form of oversight, ensuring the relay's operation remains transparent and trustworthy. This aligns with the Ethereum community's ethos of client diversity and decentralization.

Finally, monitor relay performance and governance activity as part of your regular validator maintenance. Tools like mevboost.pics provide analytics on relay market share and reliability. If a relay consistently ignores community governance or acts maliciously, the decentralized defense is for validators to remove it from their relay set. Your informed participation in governance is the key mechanism that keeps the MEV-Boost ecosystem permissionless and resilient against capture.