zkSync Era — ZK Rollup for Scalable Ethereum Smart Contracts

Introduction

zkSync Era is a Layer 2 scaling solution for Ethereum built by Matter Labs. It uses zero-knowledge proofs (ZK rollups) to batch thousands of transactions off-chain and post a single validity proof to Ethereum, achieving lower gas costs while inheriting Ethereum's security guarantees. Unlike optimistic rollups, ZK rollups provide instant finality once the proof is verified on L1.

What zkSync Era Does

• Executes EVM-compatible smart contracts at a fraction of Ethereum mainnet gas costs
• Generates zero-knowledge proofs (SNARKs) that cryptographically verify transaction validity on Ethereum
• Supports native account abstraction so every account can have custom validation logic
• Enables Hyperchains (ZK Stack) for deploying custom ZK-powered Layer 2 and Layer 3 chains
• Provides paymaster contracts that allow gas payment in any ERC-20 token or sponsored transactions

Architecture Overview

zkSync Era processes transactions in a sequencer, executes them in the zkEVM, and generates SNARK proofs in a prover pipeline. The sequencer orders transactions and produces blocks. The prover compiles execution traces into zero-knowledge circuits and generates proofs. These proofs are submitted to the L1 verifier contract on Ethereum, which validates correctness. State diffs and calldata are posted to Ethereum for data availability.

Self-Hosting & Configuration

• Run a local development node with npx zksync-cli dev start for testing
• Deploy contracts using Hardhat with the @matterlabs/hardhat-zksync plugins
• Use zksync-cli for bridging assets, checking balances, and interacting with contracts
• Configure custom networks in Hardhat config pointing to Era mainnet or testnet RPC endpoints
• Set up a ZK Stack Hyperchain using the zk_inception tool for custom L2/L3 deployments

Key Features

• Zero-knowledge proofs provide cryptographic transaction validity without revealing execution details
• Native account abstraction makes every account a smart contract with custom authentication logic
• Paymaster support enables gasless transactions or gas payment in any ERC-20 token
• ZK Stack allows deploying sovereign ZK rollup chains that settle to Ethereum
• EVM compatibility through zkEVM lets existing Solidity contracts deploy with minimal modifications

Comparison with Similar Tools

• Optimism/OP Stack — uses fraud proofs with a 7-day challenge period; zkSync uses validity proofs for faster finality
• Arbitrum — optimistic rollup with lower proof overhead; zkSync provides cryptographic guarantees instead of game-theoretic security
• StarkNet — ZK rollup using Cairo language; zkSync Era supports Solidity via zkEVM
• Polygon zkEVM — another ZK rollup with EVM equivalence; zkSync uses a different proof system and compiler approach
• Scroll — ZK rollup targeting full EVM equivalence; zkSync offers native account abstraction and paymasters

FAQ

Q: Is zkSync Era EVM-compatible? A: Yes, with caveats. Solidity and Vyper contracts compile via zkSync's custom compilers (zksolc/zkvyper). Most contracts work, but some EVM opcodes behave differently in the zkEVM.

Q: How do zero-knowledge proofs help with scaling? A: ZK proofs compress thousands of off-chain transactions into a single proof verified on Ethereum. This reduces gas costs while maintaining L1 security.

Q: What is native account abstraction? A: Every account on zkSync Era is a smart contract by default, enabling custom signature validation, multi-sig, session keys, and social recovery without ERC-4337.

Q: What is ZK Stack? A: ZK Stack is the modular framework for deploying custom ZK-powered chains (Hyperchains) that settle to Ethereum. Each chain can customize its data availability, sequencer, and token.

Sources

• https://github.com/matter-labs/zksync-era
• https://docs.zksync.io/