Like the high-frequency trading (HFT) cables that run under the Atlantic Ocean, flash minibuilders are invisible yet essential. They ensure that when you click "swap" on your favorite DEX, the price is fair, the liquidation happens on time, and the blockchain remains solvent.
Use Go or Rust to create an RPC server that accepts eth_sendBundle requests but does not propagate them to the public mempool.
Consider a simple arbitrage scenario: On Chain A, token X costs $100; on Chain B, token X costs $101. A classic arbitrage opportunity. In a public mempool, the first bot to broadcast its transaction wins. However, if a second bot uses a Flash Minibuilder with a direct fiber-optic connection to a validator, the second bot will win every time.
A is not a full block builder. Instead, it is a specialized, high-velocity engine designed to construct "miniblocks" or partial block bundles with extreme efficiency. These miniblocks are usually composed of time-sensitive transactions—often MEV strategies like arbitrage or liquidations—that must be executed within a single slot or even a sub-slot timeframe.
Establish direct TCP connections to validators' engine_api endpoints. Submit your miniblock as a engine_forkchoiceUpdated call with a payload attribute.