Users of decentralized finance (DeFi) applications face significant risks from adversarial actions that manipulate the order of transactions to extract value from users. Such actions—an adversarial form of what is called maximal extractable value (MEV)—impact both individual outcomes and the stability of the DeFi ecosystem. MEV exploitation, moreover, is being institutionalized through an architectural paradigm known Proposer-Builder Separation (PBS). This work introduces a system called PROF (Protected Order Flow) that is designed to limit harmful forms of MEV in existing PBS systems. For further details, please check out our Projects Page.