Searchers

Searching on Base works a bit differently to Ethereum as there is no builder market.

WebSocket Subscriptions

Please reach out via [email protected] to get set up with an API key.

WebSocket Connection

Connect to Blink's WebSocket endpoint:

wss://baseauction.blinklabs.xyz/ws/v1/{$API_KEY}

Transaction Subscription

The V1 WebSocket requires an explicit subscription to begin receiving transaction data. Send the following message after connecting:

{
    "method": "eth_subscribe",
    "params": ["blink_partialPendingTransactions"]
}

Submitting Bids

Submit bids to:

https://baseauction.blinklabs.xyz/v1/{$API_KEY}

Bundles are submitted using the eth_sendBundle RPC call:

{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "eth_sendBundle",
    "params": [
        {
            "txs": [ 
                "txHash",     // Target transaction hash
                "rawTxHex"    // Your transaction in raw hex format
            ],
            "bidWei": "2198498724181749"  // Your bid amount in wei (string decimal)
        }
    ]
}

Auction Mechanics

Bundle Submission

• Transactions are ordered by the sequencer based on priority fee / gas

• Searchers should set prio fee to be equal to the target transaction prio fee. Transactions with a higher prio fee will be rejected.

• While we ramp up on Base, we're asking Searchers to send 50% of profits for us to pass back to originators. Our refund address is 0xAa29178FC9527fA1410305E52cfee950a2efcB9f . Send this as an ETH transfer within your backrun transaction. The value should match your bidWei parameter. See here for an example.

• This "bid" can be sent in the bundle request as a "bidWei" parameter. If you don't, the bid will be assumed to be 0 and will only be sent if there are no other bids.

• Searchers must not send directly to the sequencer (this is monitored)

• Any sandwiching will result in immediate ban (strictly monitored)

Timing and Inclusion

• With the addition of flashblocks, timing has become extremely important on Base. Each auction is at most 200ms and late backruns will likely revert on-chain.

• At the end of the flashblock, if nobody has won the backrun slot yet, the auction becomes FIFO.

• We highly recommend colocating in AWS us-east-1 for optimal latency.

Blink Monitoring

Due to nature of Base, we can't enforce auctions rules are followed in real time. For this reason, we've invested a lot in our monitoring. We monitor:

• Sandwiches of our transactions

• Searchers sending directly to sequencer

• Searchers sending to both us and directly

• Profit passed back as percentage (should be > 50%)

• Difference between bid and amount passed back

• Revert rates (especially after big competitive bids)

Breaches (depending on severity) could include:

• Reduced Flow

• Delay on websocket

• Complete Ban