The Searcher Stack

What you'll learn

• What a Searcher Actually Does
• Layer 1: Mempool Subscribers and Node Choice
• Layer 2: Simulation Engines
• Layer 3: Bundle Submission and Builder Relationships
• The Numbers: What a Searcher Actually Earns
• For Deeper Reading

Key terms

MEV (Maximal Extractable Value)

The profit a sophisticated actor can capture by reordering, inserting, or censoring transactions inside a block. Cumulative measurable Ethereum MEV exceeded $1.8B by mid-2025.

Searcher

An independent firm or individual who monitors the mempool, simulates opportunities locally, and submits bundles to builders for inclusion in blocks. The "labor" side of MEV extraction.

Mempool

The pool of pending transactions broadcast to the network but not yet included in a block. Public mempool transactions are visible to anyone; private flow bypasses it.

revm

A Rust implementation of the EVM maintained by Paradigm. The de facto simulation engine for modern searcher stacks because it is 10-50x faster than geth interpretation for repeated simulation.

Bundle

A list of transactions submitted atomically to a builder. Either all execute in the specified order at the top of a target block, or the whole bundle is excluded. Atomicity is what makes MEV economically viable.

Builder

A specialized firm that assembles Ethereum blocks from mempool transactions and searcher bundles, then sells the assembled block to validators via MEV-Boost. Major builders: Beaverbuild, Titan, Flashbots, rsync.

Flashbots Builder API

The original searcher submission endpoint, exposing eth_sendBundle and mev_sendBundle methods. Flashbots historically held 40-60% MEV-Boost share; competition has reduced that to roughly 15-25% by 2025-2026.

Coinbase transfer / priority fee

The payment a searcher makes to the block proposer (validator) in exchange for including the bundle. Typically 60-90% of gross extracted value.

Latency budget

The 100-400ms window between observing a transaction in the mempool and submitting a competing bundle. Every component of the searcher stack consumes part of this budget.

MEV-Share

Flashbots' opt-in protocol (2023) that matches user transactions with searcher bundles and refunds a share of captured MEV to the original user. Constructive MEV alternative to extractive private-mempool routing.