Uniswap

Uniswap is the largest decentralized trading and automated market making protocol on Ethereum. Uniswap Protocol is a set of smart contracts that allow for seamless, trustless swaps of tokens between users. The protocol enables anyone to create or participate in liquidity pools for any ERC20 token, making it easy to trade without worrying about counterparty risk. Uniswap has already processed over $1B worth of trades and is quickly becoming the default method for exchanging tokens on Ethereum.