The first design decision projects building with Polygon Chain Development Kit (CDK) must make is between rollup mode and validium mode. Rollup mode provides the highest degree of security, while validium mode has the lowest transaction fees. Both modes use ZK proofs for validating the state of the Layer 2 (L2), but in validium mode, the transaction data that is costly to post to Ethereum is instead stored cheaply off-chain. Projects building with Polygon CDK inevitably ask, Where does that t...