MEV-Boost in a Nutshell

MEV-Boost in a Nutshell

MEV-Boost is an implementation of proposer-builder separation (PBS) built by Flashbots for proof of stake Ethereum. Validators running MEV-Boost maximize their staking reward by selling blockspace to an open market of builders. It is estimated that validators running MEV-Boost can increase their staking rewards by over 60%.

MEV-Boost is free, open-source, neutral software built with love, for the community. For information on MEV-Boost software and roadmap, see the MEV-Boost Repository.

MEV-Boost Quickstart

  1. Install the latest version of MEV-Boost
  2. Connect MEV-Boost to desired MEV-Boost relays:
    1. ./mev-boost -mainnet -relay-check -relays relay1,relay2
    2. Remember to use the appropriate network flag for the specific network and relay URL, e.g. -mainnet, -sepolia or -goerli.
  3. Configure a supported consensus client. Detailed instructions are available on the MEV-boost testing wiki, and guides for connecting the client to mev-boost can be found in the consensus client compatibility table below.
  4. Confirm that the setup works by calling the data API to see your validator registration.

Relay List*

For a comprehensive list of relay URL endpoints by network and operator maintained by the community, please refer to:

Flashbots Relay URLs

Relay URL

Consensus Client Compatibility 👫

MEV-Boost is designed to be compatible with the standard Ethereum Builder API. This means it is compatible with all consensus and execution clients. You can find guides for installing with your favorite consensus client below!

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Testnet ready

MEV-Boost Updates 🎯

We are writing regular updates about MEV-Boost development, adoption and community, for anyone interested in keeping up with our progress:

MEV-Boost Status Update - Sep 9-Sept 22, 2022
September 23, 2022
Introducing The Flashbots Transparency Dashboard
September 22, 2022
Flashbots Sepolia relay now accepts external block submissions
September 13, 2022
MEV-Boost v1.0 released
September 12, 2022
MEV-Boost Status Update - Aug 27-Sept 9, 2022
September 9, 2022
Flashbots Goerli relay now accepts external block submissions
September 7, 2022
Check validator registration status on Flashbots Mainnet Relay
September 6, 2022
MEV-Boost Documentation is Live!
September 5, 2022
MEV-Boost Mainnet Relay Live!
September 1, 2022
[WIP] - Builder Payments to Block Proposers
August 29, 2022
MEV-Boost Status Update - Aug 12-26, 2022
August 26, 2022
MEV-Boost Status Update - July 29 - Aug 12, 2022
August 12, 2022
Successful MEV-boost testing through Goerli Shadow Fork 6 merge!
August 4, 2022
Understanding liveness risks from mev-boost
August 4, 2022
MEV-Boost Status Update - July 15-29, 2022
July 29, 2022
MEV-Boost Status Update - July 1-15, 2022
July 15, 2022
MEV-Boost Status Update - June 24-30, 2022
June 30, 2022
MEV-Boost Status Update - June 17-24, 2022
June 24, 2022

Builder Quickstart

External builders can submit blocks to the Flashbots Relays on Mainnet, Goerli and Sepolia networks.

See here for more details:

FAQ ⁉️

Node Operators

What is MEV?

MEV is Maximal Extractable Value. It is the profit a block proposer (miner or validator) can make through their ability to arbitrarily include, exclude, or re-order transactions from the blocks they propose.

Why should I run mev-boost?

You should run mev-boost to earn a fair share of the MEV extracted in the blocks you propose. Connecting your consensus client to mev-boost allows you to get full blocks from a network of block builders optimized for MEV extraction. This can increase validator rewards by 75.3%, or give an APR of 12.86% rather than a non-MEV APR of 7.35% from staking eth.

I am a solo validator, will I be able to run mev-boost?

Yes. mev-boost is designed to be used by any validator, no matter the size of its stake.

In Ethereum proof-of-work we had no way to prevent small miners from misbehaving and stealing MEV. Once identified, they could just get a new identity and continue misbehaving. The solution was to make a list of allowed miners that were big enough to be concerned about their reputation. Their profit would be severely affected if they were removed from the allowed list. This resulted in one more incentive for the concentration of mining power in a few organizations.

The most significant change for MEV in Ethereum proof-of-stake is that with mev-boost now validators can be permissionless. The order is reversed: instead of the Flashbots relay sending blocks or bundles of transactions to the miners, now the validators request blocks to the Flashbots relay through mev-boost. The Flashbots relay in turn requests blocks to a network of builders and gives the header of the most profitable one to the validator, while holding the payload in escrow. Once the validator signs the header, the relay sends the block payload to the proposer. If at this moment the validator decides to propose a different block, they will have signed two blocks and will be slashed.

Note that this does not mean that the system is fully permissionless and decentralized, yet. The Flashbots relay is still trusted.

Read the open research questions and join us exploring possible solutions.

How should I think about running mev-boost vs regular block construction?

The alternative to running mev-boost would be to get blocks from your local execution client, which can only get transactions from the public mempool and is not optimized for MEV extraction, so your rewards are likely to be less.

Or to implement your own builder, which is a complicated task and still leaves you with the problem of finding transactions that extract MEV and are not going through the public mempool.

How do I select which relay to run and make sure the relays are not acting maliciously?

As noted above, the system is not fully permissionless and decentralized, yet. The relay acts as a trusted escrow between the proposer and the builder. In this role it can affect both parties.

We strongly suggest you to connect mev-boost to the Flashbots relay, of course. This is actually the default, of course :). And it will be pretty profitable, stable, transparent, and fair. And fun: you will be contributing to the future explorations of the Flashbots collective, we are in this together and for the long run.

For over 2 years, at Flashbots we have been learning about MEV through the execution of our proof-of-work relay and our open research. We have collaborated with all the relevant organizations in the Ethereum ecosystem to better understand the risks of MEV and mitigate them in the best possible way. We have published our tools and data with extreme care to not break the stability of the Ethereum blockchain. Together with our friends we have been educating the other organizations in the space and assisting the people most affected by the rapid changes of the cryptographic economy.

With mev-boost we are executing the next step on our role as stewards of MEV in Ethereum. It solves the centralization problems that we saw in proof-of-work with the list of allowed miners and a single block builder. Now the remaining challenges are to design the security guarantees that enable multiple trustless relays and an auction mechanism that enables builders to get transactions and the block space for them.

Read the open research questions and join us exploring possible solutions.

Is there a list of payout addresses used by block builders to pay the proposers?

A list of payout addresses is maintained at

Block Builders

What is block building?

Block building is a new role introduced by proposer-builder separation (PBS). Using MEV-Boost, validators can sell blockspace to specialized third parties called block builders who collect and sequence transactions to produce a block. Block builders want to produce a block that maximizes the fees collected in the form of priority fees and MEV.

I want to do block building, what next?

Block builders must connect to a MEV-Boost relay in order to submit their payloads to validators for inclusion. Each relay may have different rules and provide access to different validators.

Who will run a relay? Will I be able to send blocks at the merge?

While we expect there will be several relays at the merge, block builders must be careful who they submit their payloads to. A relay has the power to censor or frontrun any block proposed by a block builder.

The Flashbots Relay ( will start accepting block proposals from any block builder and continue our policy of neutrality and transparency. Documentation on the Flashbots Relay will be released closer to the merge.

How will Flashbots make sure that the relay treats their builder fairly compared to other builders?

Our relay will publish the logs of when blocks were received by builders and when they were supplied to proposers.

We expect several relay monitoring dashboards to emerge which keep track of relay performance and help block builders and validators to select a relay.

Where can I find the API spec I need to comply with?
What are slot collisions?

Slot collisions occur when more that one relay delivers a payload for a given slot. Multiple builders build blocks for a given slot, and these blocks can be submitted to multiple relays. If a block is the most profitable block for multiple relays at a given slot, it is possible each of these relays would return the block during a getHeader request for the same slot.

What is high/low builder priority?

High/low builder prioritization works the same way it does for Flashbots searchers, which is to say that low/high priority get different simulation clusters and in times of high load, such that high-priority builders will be prioritized over low-priority builders. Reputation is just a mechanism to help mitigate DDOS attacks, but doesn't affect how Flashbots scores blocks.

This world is confusing, but we are in this together ⚡ If you have additional questions, please ask on GitHub or Discord!

Resources ⛵

Awesome List

The community is maintaining an Awesome List with all relevant MEV-Boost content and resources - check it out!


MEV-Boost logo is provided with CC0 license courtesy of @lekevicius. Download here.

We also have an avatar, courtesy of DALL-E 😄


* Users of this informational material are responsible for determining any applicable legal restrictions on any direct or derivative use of this information, including complying with applicable economic sanctions laws within their home jurisdictions.  Please also see Github’s Trade Controls page. Flashbots makes no representation or warranty as to any Relay Operator or other entity’s compliance with economic sanctions or other laws and regulations.