Immutable Contract

A smart contract whose code cannot be changed after deployment — no admin keys, no proxy, no upgrade path. Immutable contracts have a strong safety property: users can audit once and rely on that forever. Trade-off: bugs cannot be fixed, and protocol evolution requires a full redeployment with user migration. Many highly-trusted protocols (Uniswap V2, original MakerDAO, Liquity) chose immutability for the trust properties.