We are a values-aligned Ethereum block builder operating since early 2023. Our goal is to provide useful functionality for searchers. To increase your inclusion rate and gain competitive insights, searchers can send bundles to:

https://builder.gmbit.co/rpc

We maximize profit for validators and refunds for users. To help do this we employ advanced bundle merging algorithms and may pick up leftover MEV at the end of the block after it has been built. We do not share bundles with other builders, searchers, or any other 3rd parties.

Documentation

eth_sendBundle

We follow the standard eth_sendBundle interface pioneered by Flashbots. Bundles with any reverting txs will be dropped, unless those that are allowed to revert are listed under revertingTxHashes.^[1]

If the refundPercent field is set, the builder will pass refundPercent of the total bundle tip minus the burned base fee to the refundRecipient. All refunds are processed together at the end of the block as a single transaction (to save gas and allow for smaller refunds). If the cost of the refund transfer is greater than the refund amount, the bundle will still be included, but no refund will occur.

curl --data '{
    "method": "eth_sendBundle",
    "params": [{
      "txs": ["0xf49...", "0x58a..."],  // Array[String], list of signed txs to execute in an atomic bundle
      "blockNumber": "0x10D033F",       // String, a hex encoded block number for which this bundle is valid on
      "minTimestamp": 1688588473,       // (Optional) Number, min timestamp this bundle is valid (seconds since epoch)
      "maxTimestamp": 1688588500,       // (Optional) Number, max timestamp this bundle is valid (seconds since epoch)
      "revertingTxHashes": ["0xa4..."], // (Optional) Array[String], list of tx hashes allowed to revert
      "refundPercent": 90,              // (Optional) Number, the percent (from 0 to 99) of bundle tip that should be passed back to the refundRecipient
      "refundRecipient": "0xf45..."     // (Optional) Address, account that will receive the refund from this bundle, defaults to the sender of the first tx
    }],
    "jsonrpc": "2.0",
    "id": 1
  }' \
  -H "Content-Type: application/json" \
  -X POST "https://builder.gmbit.co/rpc"

Response

Using the transaction hash of one of the transactions in your bundle (e.g. target tx you are backrunning) you can see how you compared to other bundles with the auction stats dashboard. In the search results, you can see your bundle by its hash.

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "bundleHash": "0xd4da0d..."
  }
}

Public Keys

Our builder only submits from the following public keys. Any other public keys not included in the list below should be considered unrelated to our builder.^[2]

0xae7f0dd473d986b277539cca610aba02c437082ac504b998079edf20b0258db6cc6f6f27220d6428283691db53e62c3b
0x817a0833086f904e1bc593dbfb416f2df86f6b2f27bb218ac78f60c63345cb4a013d2bc38dea4bef3df4a2c49e274e12
0xa28379a57611153dd617fe588a97665dd958fefd160265a60a75a1cbed19bb62245fc3e604931a860303387518f79294
0x96a3473f060c37be3eaca7bd88a9cc644ce5d979bfc655e68ef148bd111a856df94d2ae4186ae2ae35e4516dda21aa29
0xaa6cc56cd783b18abea9ed92bd1e5731f40dfdf56595794b6b5ab640fa926309fde68253359dd36608983e54d98567f0

[1]: Bundles may still revert due to chain reorgs, or unbundling at the relay or validator level. We try our best to ensure bundle atomicity, but there could also be risk due to bugs at the builder level. Be mindful of this when using this free API, and use it at your own risk.

[2]: The "extra data" field in the block header is not a reliable way to identify the builder for a given block as impersonation is prevelant.