zkSync vs Starknet: Comparing the Top ZK-Rollups

zkSync Era and Starknet are two of the leading zero-knowledge (ZK) rollups on Ethereum, but they take different technical approaches: zkSync Era pursues zkEVM compatibility so existing Solidity contracts largely work with minimal changes, while Starknet uses its own custom Cairo virtual machine and STARK-based proofs, prioritizing proving efficiency over direct EVM compatibility.

Both fall under the umbrella of validity rollups described in our optimistic vs. ZK rollups guide, meaning both rely on cryptographic proofs rather than fraud-proof challenge windows, but the underlying execution environments diverge significantly.

Execution environment: zkEVM vs. Cairo VM

zkSync Era implements a zkEVM, a virtual machine designed to closely mirror Ethereum's own execution environment, so Solidity and Vyper contracts can generally be deployed with little modification. This lowers the barrier for existing Ethereum teams to migrate or deploy in parallel.

Starknet uses Cairo, a custom-built language and virtual machine designed from scratch around efficient STARK-proof generation rather than EVM compatibility. Developers need to write or port contracts specifically for Cairo, a real barrier compared to zkEVM approaches, though Starknet's tooling has matured significantly since launch.

Proof systems: SNARKs vs. STARKs

zkSync Era primarily relies on SNARK-based proof systems, which tend to produce smaller proofs but, depending on the specific construction, may require a trusted setup ceremony for certain parameters.

Starknet uses STARK proofs, which don't require a trusted setup and are considered more resistant to future quantum computing attacks due to their reliance on hash-based cryptography rather than elliptic curve assumptions, though STARK proofs have historically been larger, which can affect on-chain verification costs.

Account abstraction

Both networks have invested heavily in native account abstraction, letting accounts behave like programmable smart contracts by default rather than being limited to simple externally-owned wallets. This can enable features like paying gas in different tokens, batched transactions, and custom authentication logic such as social recovery, without needing separate smart-contract-wallet infrastructure bolted on afterward.

Developer ecosystem considerations

zkEVM compatibility gives zkSync Era an easier on-ramp for the large existing pool of Solidity developers and audited Ethereum contract code. Starknet's Cairo ecosystem is smaller in comparison but has grown steadily, and some developers building performance-sensitive applications specifically prefer Cairo's design, since it wasn't constrained by needing to replicate the EVM's historical design choices.

Decentralization status

Both networks currently rely on centralized sequencer and prover infrastructure operated primarily by their respective core teams, Matter Labs for zkSync Era and StarkWare for Starknet, with decentralization roadmaps still in progress for both. Treat this as an active, shared risk factor across the ZK-rollup space generally, as discussed in our sequencer decentralization guide, rather than something unique to either project.

Ecosystem expansion frameworks

Both projects have released frameworks allowing other teams to launch their own chains built on the same core technology. Matter Labs offers the ZK Stack, enabling "hyperchains" that share zkSync's proving infrastructure, while StarkWare has similarly worked toward letting other application-specific chains leverage Starknet's STARK-proving technology. This mirrors a broader industry pattern, also seen with Optimism's OP Stack, of major rollup teams positioning their technology as reusable infrastructure rather than a single isolated product.

Fee dynamics

Both networks' transaction costs reflect a combination of proof-generation expense and the cost of posting data back to Ethereum, discussed generally in our data availability guide. zkSync Era's SNARK-based proofs are typically cheaper to verify on-chain due to smaller proof sizes, while Starknet's STARK proofs, though historically larger, benefit from recursive proving techniques that can improve efficiency as transaction volume scales. In practice, day-to-day fees on both networks tend to be broadly comparable and low relative to Ethereum mainnet.

Which one is right for a given project

Teams with substantial existing Solidity codebases and a preference for minimizing migration friction often lean toward zkSync Era's closer EVM familiarity. Teams building new applications from scratch, particularly ones where performance-sensitive or highly custom logic benefits from a purpose-built language, sometimes prefer Starknet's Cairo environment despite its steeper initial learning curve. Neither preference is universally correct, and plenty of successful projects exist on both networks.

zkSync Era vs. Starknet at a glance

Factor	zkSync Era	Starknet
Execution environment	zkEVM (EVM-compatible)	Cairo VM (custom)
Proof system	SNARK-based	STARK-based
Trusted setup	Depends on construction	Not required
Developer familiarity	High, near-Solidity compatible	Requires learning Cairo
Account abstraction	Native	Native

Bottom line

zkSync Era and Starknet both push the boundaries of zero-knowledge rollup technology but make different bets on developer experience: zkSync Era optimizes for immediate EVM familiarity, while Starknet optimizes for a custom, proving-efficient execution environment at the cost of a steeper learning curve. Neither has fully decentralized its sequencer or prover infrastructure yet, so evaluate both similarly on that front. Review our standalone guides to zkSync Era and Starknet for deeper technical detail, and check current adoption figures on our chains page before choosing where to build or deploy capital.