Glossary
Private Mempool
A non-public alternative to Ethereum's public mempool — wallets and dApps submit transactions privately to block builders, defeating sandwich attacks.
Ethereum's default mempool is fully public, which is what lets front-running and sandwich attacks happen. A private mempool — Flashbots Protect, MEV Blocker, BloxRoute's private tx — routes transactions directly to selected builders without exposing them to the public pool.
Searchers never see the transaction until it lands on-chain, so they cannot front-run or sandwich. The trade-off is mild centralization on a handful of relay operators. Modern wallets are increasingly private-mempool-by-default.