What is zkSync?
zkSync is a Layer 2 scaling solution for Ethereum built on zero-knowledge (ZK) rollup technology. Developed by Matter Labs, it bundles hundreds of transactions off-chain, generates a cryptographic proof that they’re valid, and submits only the proof to Ethereum mainnet — reducing gas costs by ~100x while inheriting Ethereum’s security.
zkSync is one of the leading ZK-rollup projects alongside StarkNet, Polygon zkEVM, and Linea.
zkSync Era (ZK Stack)
The current major version, zkSync Era (formerly zkSync 2.0), launched on mainnet in March 2023. Key features:
| Feature | Description |
|---|---|
| EVM-compatible | Runs Solidity smart contracts with minimal changes |
| Native Account Abstraction | Built-in ERC-4337 support (smart accounts, gasless txs) |
| Low fees | ~10–50x cheaper than Ethereum L1 |
| Fast confirmation | Soft confirmation in seconds; full proof in hours |
| Type 2 EVM | Not a perfect EVM equivalent, but close enough for most dApps |
ZK Stack
Matter Labs open-sourced the ZK Stack — a modular framework for building custom ZK-rollups (called “hyperchains”) using zkSync’s technology. Similar to how OP Stack enables anyone to launch an Optimistic rollup.
How zkSync Works
Users transact on zkSync
↓
Sequencer orders + batches transactions
↓
Prover generates a ZK validity proof (STARK → SNARK)
↓
Proof submitted to Ethereum L1 smart contract
↓
L1 contract verifies the proof (cheap) → state is finalizedUnlike Optimistic rollups (which assume transactions are valid and have a 7-day challenge window), ZK-rollups mathematically prove every transaction is valid. There’s no challenge period — once the proof is verified, the state is final.
zkSync vs Other L2s
| Feature | zkSync Era | Arbitrum | Optimism | StarkNet |
|---|---|---|---|---|
| Technology | ZK-rollup | Optimistic | Optimistic | ZK-rollup |
| EVM compat | Type 2 | Full EVM | Full EVM | Cairo (not EVM) |
| Withdrawal | Hours (proof) | 7 days | 7 days | Hours (proof) |
| Account abstraction | Native | Via ERC-4337 | Via ERC-4337 | Native |
| Token | ZK (launched 2024) | ARB | OP | STRK |
The ZK Token Airdrop
zkSync’s ZK token launched in June 2024 with one of the largest airdrops in history — 3.6B tokens (17.5% of supply) distributed to early users. The airdrop criteria were controversial:
- Based on activity snapshots across multiple dates
- Sybil filtering removed millions of farming wallets
- Many active users were excluded (eligibility disputes)
zkSync Ecosystem
Notable protocols on zkSync Era:
- SyncSwap — leading DEX
- EraLend — lending protocol
- Mute.io — DEX + bond platform
- LayerZero — cross-chain messaging (bridges)
- Chainlink — price oracles
TVL peaked around $600M in mid-2024, settling lower post-airdrop.
Strengths and Limitations
Strengths:
- Mathematical finality (no 7-day withdrawal delay)
- Native account abstraction
- Growing ecosystem and developer tooling
- ZK Stack enables custom appchains
Limitations:
- Prover costs are high (though decreasing)
- Not a perfect EVM equivalent (some Solidity features differ)
- Centralized sequencer (decentralization roadmap in progress)
- Lower TVL and ecosystem than Arbitrum/Optimism
Frequently Asked Questions
Q: Is zkSync safe? A: ZK-rollups are considered the most secure L2 design because validity proofs mathematically guarantee correctness. However, the current sequencer is centralized — a risk that decreases as Matter Labs decentralizes.
Q: How do I bridge to zkSync? A: Use the official bridge at bridge.zksync.io, or cross-chain bridges like Orbiter Finance, LayerZero, or Across.
Q: What’s the difference between zkSync and Polygon zkEVM? A: Both are ZK-rollups. Polygon zkEVM aims for full EVM equivalence (Type 3). zkSync Era is Type 2 (mostly compatible with minor differences). zkSync also has native account abstraction that Polygon zkEVM lacks.