zkEVM comparison: Polygon vs zkSync vs Scroll

Both ZK rollups and optimistic rollups (Arbitrum, Optimism) batch transactions and post them to Ethereum mainnet, but they use different fraud prevention mechanisms. Optimistic rollups assume transactions are valid and allow a 7-day challenge period where fraud proofs can be submitted to contest invalid batches — this creates a 7-day withdrawal delay from L2 to L1. ZK rollups post mathematical proofs (zero-knowledge proofs) with each batch that cryptographically prove correctness — no challenge period is needed, enabling faster withdrawals (hours versus 7 days). ZK rollups provide stronger security guarantees but historically required more proving time to generate; hardware acceleration and optimised proving systems have largely closed this gap in 2025–2026.

For Type 2 zkEVMs (Polygon zkEVM, Scroll), the vast majority of Ethereum smart contracts deploy and run without modification. The exceptions are contracts that use specific precompile operations that are implemented differently or not yet supported on the specific zkEVM, and contracts with very specific assembly optimisations that depend on exact EVM behaviour. For zkSync Era (Type 4), most Solidity contracts compile and run correctly but bytecode-level compatibility is not guaranteed — contracts that rely on CREATE2 address derivation, specific gas behaviour, or low-level assembly may require adjustments. Test deployment on the target zkEVM in a staging environment before production migration to identify any compatibility issues early.

zkEVM transaction fees are typically 10–100× lower than Ethereum mainnet, depending on mainnet gas prices and network congestion. During high Ethereum mainnet activity, the cost differential widens further. Typical simple transfer costs: Ethereum mainnet $3–50, zkEVM L2 $0.01–0.30. Complex DeFi interactions: mainnet $20–200, zkEVM $0.05–2. The fee reduction is the primary driver for user and application migration from mainnet to L2. Fees vary between zkEVM implementations and fluctuate with batch size and prover cost — zkSync Era and Polygon zkEVM typically have the lowest fees due to optimised proving systems and higher transaction volume amortising fixed batch costs.

ZK Stack is Matter Labs' open-source framework for building custom blockchains using zkSync's zkEVM technology — similar to how Polygon CDK allows building custom chains on Polygon's zkEVM. Enterprises and projects can use ZK Stack to launch their own "hyperchain" that uses zkSync's proof system, settles to Ethereum, and can bridge assets to and from the zkSync Era public network. This is the enterprise customisation layer: a private financial institution chain built on ZK Stack inherits zkSync's security without sharing infrastructure with the public network. The hyperchain model allows custom execution environments, access controls, and gas token configurations while remaining connected to the broader Ethereum security and liquidity ecosystem.

zkEVM security is theoretically equivalent to Ethereum mainnet security for the correctness of transaction execution — the ZK proofs provide a mathematical guarantee that the state transitions are valid. The practical security differences are in the trust assumptions around the rollup's operational infrastructure. Most zkEVM deployments retain some centralised elements (sequencer for transaction ordering, prover for proof generation) that introduce trust assumptions absent from Ethereum's fully decentralised consensus. Decentralisation of sequencers and provers is an active development area — all three projects (Polygon, zkSync, Scroll) have published roadmaps for decentralising these components. Current deployments are appropriate for applications where the security of the underlying proof system is the primary concern; fully decentralised operation comparable to Ethereum is a medium-term target for all three implementations.

The choice depends on the primary use case. For enterprise private chain requirements (permissioned access, custom gas token, institutional compliance controls), Polygon CDK is the most mature tooling with the strongest enterprise support relationships. For consumer-facing applications where UX (gasless transactions, account abstraction) and low transaction costs are priorities, zkSync Era's native AA and competitive fees make it the leading choice. For DeFi protocols or applications requiring the highest EVM compatibility to avoid migration complexity, Scroll or Polygon zkEVM are the most compatible options. Evaluate based on your specific compatibility requirements, ecosystem (which DeFi protocols, bridges, and infrastructure exist on each network), and whether you need custom chain infrastructure or are deploying to the public network.

All three zkEVM networks support the standard Ethereum development toolchain: Hardhat and Foundry for smart contract development, testing, and deployment; Ethers.js, Viem, and Web3.js for frontend integration; MetaMask and WalletConnect for wallet integration; and The Graph for indexing and querying on-chain data. zkSync Era has some additional tooling requirements (zkSync-specific Hardhat plugins for deployment) due to its custom VM architecture, but these are well-documented and broadly adopted by the developer community. OpenZeppelin's standard contracts deploy without modification to all three networks. The development experience is substantially the same as Ethereum mainnet — the main operational difference is configuring the RPC endpoint for the target network.

All three networks provide official bridges for moving ETH and ERC-20 tokens between Ethereum mainnet and the L2. The official bridge (typically a smart contract on both chains) is the most secure path but has withdrawal delays (hours for ZK rollups due to proof generation time). Third-party fast bridges (across, Across Protocol, Hop Protocol) provide near-instant cross-chain transfers by using liquidity providers who front the destination funds and wait for L2 settlement themselves — at the cost of a small fee premium. For enterprise deployments, evaluate bridge security audits carefully — bridges have been the source of the largest DeFi exploits, and cross-chain asset movements for significant amounts should use audited, battle-tested bridge infrastructure rather than newer unaudited alternatives.