As far as I know, the flashbots bundles can be found in flashbots explorer (https://flashbots-explorer.marto.lol/) when their block is built by Flashbots: Builder (you can find more mev-builder at https://etherscan.io/accounts/label/mev-builder). However, the blocks build by other mev-builders, such as beaverbuild, builder0x69, and eth-builder, can not be found in flashbots explorer. How to find these bundles?

1 Answer 1


On etherscan in the block page, there is the field "Fee Recipient" where is possible to identify the builder who propose the block.

enter image description here

It is not a complete information since one can not know the bundles, but is possible to supose some bundles inside the block, mainly because some interactions are to MEV contracts.

EDIT: In EigenPhi is possible to browse transactions that are part of MEV attacks.

  • 1
    Thanks! It seems that Flashbots: Builder is using Flashbots relay (you can find all mev-relays at ethstaker.cc/mev-relay-list). However, it's not clear to me which relay is beaverbuild or builder0x69 using. Is there a many-to-many relationship between builer and relay?
    – Yuhua Wei
    Commented Feb 20, 2023 at 16:33
  • 1
    @YuhuaWei Sorry, i forgot to tell you, but take a look at EigenPhi, in which you can find which transactions are MEV attacks. Accordingly to https://www.relayscan.io/ list, builder0x69 is using boost-relay.flashbots.net, relay.ultrasound.money, and some others.
    – Rafael
    Commented Feb 20, 2023 at 17:29
  • Great! I have two questions. 1) The data of the website (mevboost.pics) shows that about 93.7 k blocks built by builder0x69 use flashbots as relay, while only about 6k blocks use ultra sound. What determines the connection of the same builder to different relays? 2) Different relays have their owning flitering, censorship and MEV strategies, as you can see at ethstaker.cc/mev-relay-list. As an MEV researcher, how can one make sure that the builder who accepts his bundles will connect to the relay with the properties he desires, such as no filtering for frontrunning?
    – Yuhua Wei
    Commented Feb 21, 2023 at 16:14
  • 1
    1) Builders interact with relays using the Relay API specification, and is totally possible to interact with two or more relays, but i not aware if some relays demand the builder be whitelisted. 2) Beside to watch the builder activities using the links above i do not know other method to make sure that the builder will connect to the relay with the properties desired.
    – Rafael
    Commented Feb 21, 2023 at 17:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.