CoFiX is a Computable Trading System. DeFi projects have a problem; they cannot calculate and manage risk because they are not using an oracle with controllable and computable risk. The NEST oracle solves this problem by providing a reliable price feed with a computable risk factor that does not rely on centralized infrastructure. By using the NEST oracle, we can provide an entirely new DEX, CoFiX, that brings reliable prices and a computable risk factor for traders and market makers. This article will discuss the background of DEX's today, explain in detail the works of our new DEX, CoFiX, and how we expect it to become an essential product in the space.