The 0x API is the easiest way to source liquidity from 0x Mesh as well as on-chain sources such as Kyber, Uniswap, Oasis, Curve and other decentralized exchange networks. While the 0x Core Team hosts a version of the 0x API (subject to the 0x Terms of Service), all the code is open source and available at the 0x-API GitHub repo.
Matcha is a DEX built by 0x Protocol. It utilizes the 0x API and 0x Mesh, to leverage aggregated liquidity and price information from Kyber, Uniswap, Oasis, and other sources. By using smart order routing, Matcha automatically provides the end-user with the best possible price for their trade.
0x offers a suite of APIs to enable crypto trading, build frictionless apps, unlock limit orders, show order history, and curate tokens. It provides a fully integrated suite of APIs designed to work seamlessly together, offering core building blocks to create powerful Web3 apps.