Bid on transactions

The private mempool broadcasts an auction for every transaction it receives. The auction reveals certain parts of the transaction that searchers can use to post a backrun bid.

MEVBlocker Bots: Migrating from MEVBlocker to Merkle auctions is described here: MEVBlocker compatibility

1. Listen for pending auctions

Auctions last for 1.5 second and are streamed over the following websocket:

wss://mempool.merkle.io/stream/auctions

When starting your bidder, the current list of open auctions can be fetched using the following endpoint:

http://mempool.merkle.io/auctions

Here is an example of an what an auction looks like:

{
  "chain_id": 1, // 1 (ethereum), 137 (polygon) or 56 (bsc)
  "id": "6397ad29b5c6edb1a7eeea18",
  "fee_recipient": "0x1E8e81dC3B221885b386e3d1c9efe93fc2863B24",
  "transaction": {
    "data": "0502b1c500000000000000000000000004969cd041c0cafb6ac462bd65b536a5bdb3a67000000000000000000000000000000000000000000002f38ca25d4a70c3ab633d000000000000000000000000000000000000000000000000282a2d9685378c260000000000000000000000000000000000000000000000000000000000000080000000000000000000000000000000000000000000000000000000000000000100000000000000003b6d0340b767c20d9773adce84d0f0a5bc64e2f114ad3076e26b9977",
    "from": "0x37a89da7BfF274F9E773418ef49caA2aFe393D70",
    "gas": 355000,
    "hash": "0xe3f7d4b7eb34b37e47bd54cd225c79f579d2b52869d87e7b288062ef817e9445",
    "to": "0x1111111254EEB25477B68fb85Ed929f73A960582",
    "value": "0",
    "function_selector": "0x0502b1c5",
    "logs": [
      {
        "address": "0x0319000133d3AdA02600f0875d2cf03D442C3367",
        "data": "0x",
        "topics": [
          "0x5f6ebb64ba012a851c6f014e6cad458ddf213d1512049b31cd06365c2b059257",
          "0x000000000000000000000000c5017be80b4446988e8686168396289a9a62668e",
          "0x0000000000000000000000000f0a35351b1c5512e50c1c7410c59d5bc52bfe37"
        ]
      }
    ]
  },
  "closes_at": "2022-12-12T22:37:32.937Z",
  "created_at": "2022-12-12T22:37:28.937Z"
}

2. Submit bids

Polygon is different, learn how to bid on Polygon.

Bids can be submitted using any Flashbot client with the relay url https://mempool.merkle.io/relay. However, the first transaction needs to be the hash of the target transaction, since the full transaction data is not available to you.

The backrun transaction needs to make a Ether transfer to the fee recipient (0xe142006cd11b352a5d3be644978548f12348c91b in this example). The value of this transfer is considered the bid amount. merkle simulates every bid to determine the amount transferred to the fee recipient.

To recap, a bid is a bundle with 2 transactions:

• The hash of the target transaction

• a backrun: the backrun transaction must pay the fee_recipient the bid with an Ether transfer.

For example, if we wanted to bid on the auction above, the bundle would be:

[
    "0xe3f7d4b7eb34b37e47bd54cd225c79f579d2b52869d87e7b288062ef817e9445", // hash of the transaction
    "0x.....", // my backrun
]

The full request would for this example would be:

// POST https://mempool.merkle.io/relay

{
    "method": "eth_sendBundle",
    "jsonrpc": "2.0",
    "params": [
        {
            "txs": [        
                "0xe3f7d4b7eb34b37e47bd54cd225c79f579d2b52869d87e7b288062ef817e9445", // hash of the transaction
                "0x.....", // my backrun
            ] 
        }
    ]
}

The API responds with a bid id:

{
    "jsonrpc": "2.0",
    // bid uuid
    "result": "0000-0000-0000-0000"
}

Check the status of your bid using the Bid status API endpoint.