ZK Rollup

A ZK rollup (also called a Zero-Knowledge Rollup or Validity Rollup) is a type of rollup that submits a cryptographic validity proof alongside every batch of transactions rather than assuming validity by default. Because the base chain verifies that proof on-chain, "there are no delays when moving funds from a ZK-rollup to Ethereum... because exit transactions are executed once the ZK-rollup contract verifies the validity proof"—unlike an optimistic rollup, which needs a multi-day fraud-proof challenge window before a withdrawal is final. ZK rollups bundle thousands of transactions per batch and post only minimal summary data to Ethereum, using proof systems such as zk-SNARKs or zk-STARKs. zkSync Era, Starknet, and Linea are prominent ZK rollups. The trade-off is computational: generating validity proofs is expensive, and full compatibility with Ethereum's virtual machine is technically harder to build than a fraud-proof system. For tokenized domains, a ZK rollup gives the fastest path to layer-1-final ownership transfers of any rollup design.