Quick Answer: 1inch is a decentralized exchange (DEX) aggregator that routes token swaps across 200+ liquidity sources on 13+ blockchains — including Ethereum, Arbitrum, Base, BNB Chain, Polygon, and Solana — to find users the best possible swap rate with minimal slippage and MEV protection. It charges zero platform fees: users pay only network gas fees and liquidity pool fees (typically 0.05%–0.30%). 1inch processes cumulative swap volume exceeding $300 billion and is widely considered the leading DEX aggregator for traders who need best-price execution across fragmented DeFi liquidity. Its Fusion protocol routes orders through professional resolvers via Dutch auctions, eliminating front-running risk on eligible swaps.