Bundles Received Daily

1.34 million

Processed Refunds Daily



Top 6

Relays Connected


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:


We maximize profit for validators and refunds for users. To help do this we employ advanced bundle merging algorithms and 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.



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"


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..."

[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.