# zkSync Era — ZK Rollup for Scalable Ethereum Smart Contracts

> zkSync Era is a Layer 2 zero-knowledge rollup on Ethereum that provides EVM-compatible smart contract execution with lower gas costs and higher throughput while inheriting Ethereum's security through validity proofs.

## Install

Save in your project root:

# zkSync Era — ZK Rollup for Scalable Ethereum Smart Contracts

## Quick Use
```bash
# Set up a zkSync development environment
npx zksync-cli create my-project --template hardhat_solidity
cd my-project
npm install
npx hardhat compile
npx hardhat deploy-zksync --script deploy.ts
# Or interact via cast
cast send --rpc-url https://mainnet.era.zksync.io <contract> "function()" --private-key $PK
```

## 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/

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Source: https://tokrepo.com/en/workflows/asset-3069e3e1
Author: AI Open Source