Universal Upgradeable Proxy Standard

The universal upgradeable proxy standard is an evolution of proxy design that moves the upgrade logic into the implementation contract itself. This allows for more flexible upgrades and reduces the complexity of the proxy contract.

By placing the logic in the implementation, the proxy becomes a simple, lightweight contract that only forwards calls. This pattern is often referred to as UUPS and is highly gas-efficient.

It requires the implementation contract to handle the upgrade logic securely. It is increasingly favored for its balance of security and efficiency in modern Ethereum development.