The Vibe: Jumping ahead in line to profit from someone else’s big trade—like peeking at their order in the queue and buying/selling first to make money off the price move they cause.
The Details: Front-running is when someone (usually a bot or searcher) sees your pending transaction in the public mempool and quickly submits their own trade before yours gets included in a block. They profit from the price change your trade will cause. On DEXs with AMMs, this often leads to sandwich attacks: the bot buys first (driving price up), your trade executes at the worse price, then the bot sells immediately for profit. It creates extra slippage for you and risk-free gains for them. Front-running is a form of MEV and is common on public mempools (Ethereum, BSC, etc.). In 2026, private relays, MEV protection tools, and some chains’ designs reduce it, but it still happens on unprotected trades.
Pro Tip: Protect yourself with MEV-safe tools: use wallets or DEXs with private transaction relays (Flashbots Protect, MEV Blocker, CoW Swap). Set low slippage tolerance (0.5–1%) and split large trades into smaller ones. Avoid high-volatility swaps during busy times—preview expected output and use aggregators that hide your trade from the public mempool.