Searchers

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

Requirements

By participating in the Blink Base FCFS auction, searchers agree to the following:

• No frontrunning of any kind. Sandwiching or any other form of frontrunning will result in an immediate ban.

• Self-submission to the sequencer. Searchers are responsible for submitting both the target transaction and their own backrun transaction directly to the sequencer. Blink does not submit on your behalf.

• Attribution via eth_sendBundle. Searchers must send an eth_sendBundle request to Blink for attribution purposes. The bidWei field is accepted but ignored — it does not affect ordering.

• Profit kickback of at least 75%. Searchers must send at least 75% of their profits to the address below as a native ETH transfer within the backrun transaction.

Kickback address: 0x743be0db30148336A3DB479f19d4e1828b293869

Example payment transaction: 0x4860d8e...

---

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 Attribution Bundles

Submit bundles to:

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

Bundles are submitted using the eth_sendBundle RPC call. The first element must be the target transaction hash; subsequent elements are your raw backrun transaction(s):

{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "eth_sendBundle",
    "params": [
        {
            "txs": [
                "0xTargetTxHash",  // Target transaction hash (required)
                "0xRawBackrunHex"  // Your backrun transaction in raw hex format (required)
            ],
            "bidWei": "0"          // Ignored in V1 — include any value for compatibility
        }
    ]
}

The bundle must contain at least two transactions. The bidWei field is parsed for compatibility but has no effect on auction ordering or outcome.

---

Auction Mechanics

How it works

• Blink broadcasts pending transactions to connected searchers via WebSocket.

• Searchers submit their backrun transaction directly to the sequencer alongside the target transaction. This results in a FCFS auction.

• Searchers also send an eth_sendBundle to Blink for attribution tracking.

• Transactions are ordered on-chain by the sequencer based on priority fee. Set your backrun priority fee equal to the target transaction's priority fee — transactions with a higher priority fee will result in ejection from the searcher pool.

Profit Kickback

• Send at least 75% of your profit as a native ETH transfer to 0x743be0db30148336A3DB479f19d4e1828b293869 within your backrun transaction.

• This allows Blink to pass profits through to originator sources.

Timing and Inclusion

• Each auction window is approximately 50ms. Late backruns will likely revert on-chain due to flashblock timing.

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

---

Blink Monitoring

Blink actively monitors for rule violations and will take action accordingly:

• Frontrunning or sandwiching of Blink transactions

• Searchers sending directly to the sequencer without attribution

• Profit kickback percentage (must be > 75%)

Violations may result in:

• Reduced flow

• WebSocket delay

• Complete ban