Zero-knowledge rollups are widely considered the endgame for blockchain scaling. They combine the throughput benefits of off-chain execution with cryptographic proofs that guarantee correctness, providing security equivalent to the base layer. Beyond scaling, zero-knowledge proofs enable privacy-preserving applications that can verify computations without revealing underlying data. Here is how the technology works and where it is heading.
Zero-Knowledge Proof Fundamentals
A zero-knowledge proof allows a prover to convince a verifier that a statement is true without revealing any information beyond the truth of the statement itself. In the context of rollups, the prover demonstrates that a batch of transactions was executed correctly — that all state transitions followed the rules — without the verifier needing to re-execute every transaction. The two main proof systems are ZK-SNARKs (Succinct Non-interactive Arguments of Knowledge), which produce small, fast-to-verify proofs but require a trusted setup, and ZK-STARKs (Scalable Transparent Arguments of Knowledge), which require no trusted setup and are quantum-resistant but produce larger proofs. Both are being actively developed and optimised for blockchain applications.
ZK-EVM Classifications
Vitalik Buterin's classification of ZK-EVMs by compatibility level is essential for understanding the ecosystem:
- Type 1 (fully Ethereum-equivalent): Proves the entire Ethereum execution, including all opcodes and precompiles. Maximum compatibility but highest proving cost. Targets protocols like Taiko.
- Type 2 (EVM-equivalent): Supports all EVM opcodes but may differ in gas costs and some edge cases. Scroll and Polygon zkEVM target this level, offering near-full compatibility with existing Solidity tooling.
- Type 3-4 (partial or language-level): Support Solidity or Vyper compilation but with modified execution environments. zkSync Era and StarkNet (using Cairo) fall here, offering better performance at the cost of requiring some code modifications.
Privacy Applications
Beyond scaling, zero-knowledge proofs enable privacy-preserving blockchain applications. Users can prove they meet certain criteria — age verification, accredited investor status, sufficient balance — without revealing the underlying data. Private transactions allow transfers without exposing sender, receiver, or amount on the public ledger while still proving validity. Identity solutions like Polygon ID use ZK proofs for verifiable credentials that protect user privacy. These privacy capabilities are increasingly important for enterprise adoption and regulatory compliance, where data minimisation principles require sharing only what is necessary.
Developing for ZK Rollups
For developers, the ZK rollup experience varies by implementation. Type 2 ZK-EVMs like Scroll and Polygon zkEVM allow deploying existing Solidity contracts with minimal changes — the same development tools (Hardhat, Foundry) and libraries (OpenZeppelin) work. StarkNet requires learning Cairo, a purpose-built language optimised for ZK proof generation. zkSync Era supports Solidity but uses a custom compiler. The ecosystem is maturing rapidly, with improved developer tooling, growing liquidity, and expanding application ecosystems on each platform. At Born Digital, we help projects evaluate ZK rollup options and develop applications that leverage the scaling and privacy benefits of zero-knowledge technology.