Searcher
A searcher is an entity that scans the blockchain for MEV opportunities — arbitrage paths, liquidation opportunities, sandwich targets — and submits transaction bundles to extract that value. Searchers run custom infrastructure: modified Ethereum clients that simulate transaction inclusion under different ordering scenarios, mempool listeners that detect profitable opportunities faster than competitors, and bundle-submission pipelines to builders and relays. Successful searchers combine quantitative modeling (identifying cross-venue price discrepancies) with latency optimization (co-location, direct network peering). Searchers typically do not build entire blocks; they submit bundles to builders, who include them in block proposals in exchange for a portion of the extracted value. The searcher market is adversarial and highly competitive — multiple searchers racing for the same opportunity drives gas prices up and margins toward zero in what are known as Priority Gas Auctions.