ZKsync is a family of layer 2 networks that scale Ethereum using zero-knowledge proofs. It was developed by Matter Labs. The main network, ZKsync Era, processes transactions on its own chain and then proves to Ethereum that they were processed correctly. Users get lower fees while final settlement stays on Ethereum. The project's site is zksync.io.
Why Layer 2 Exists
Ethereum's base layer handles a limited number of transactions per block. When demand is high, users bid against each other and fees rise. Rollups address this by executing transactions elsewhere and posting compressed results to Ethereum. Ethereum's own roadmap expects most everyday activity to happen on rollups, with the base layer acting as the settlement and data layer.
How a ZK-Rollup Works
A zero-knowledge proof lets one party prove that a statement is true without the verifier redoing the work behind it. In a rollup, the statement is that a batch of transactions followed the rules. The ethereum.org page on ZK-rollups explains the model in depth.
On ZKsync Era the flow looks like this:
- Users send transactions to the network.
- A sequencer orders and executes them and gives users a fast confirmation.
- Transactions are grouped into batches, and a prover generates a validity proof for each batch.
- The proof and the data needed to rebuild the state are posted to Ethereum.
- A contract on Ethereum checks the proof and accepts the new state.
Checking a proof is far cheaper than re-running every transaction, and that is where the savings come from. ZKsync's proof system uses STARK-based proofs that are wrapped in a SNARK so verification on Ethereum stays cheap.
ZK-Rollups vs Optimistic Rollups
Optimistic rollups such as Arbitrum and Optimism assume batches are valid and allow about seven days for anyone to challenge them with a fraud proof. Withdrawals through their official bridges wait out that window.
A ZK-rollup proves each batch up front, so there is no challenge period. Withdrawals to Ethereum finish once the proof is verified and the batch is executed. In practice this has taken hours on ZKsync Era, partly because the network applies a safety delay before batches are executed. That is still far shorter than a week.
The cost is complexity. Generating proofs is computationally heavy, and proving Ethereum-style smart contracts took years of engineering.
A Short History
- June 2020: the first version, now called ZKsync Lite, launched on Ethereum mainnet. It supported payments and simple swaps but not general smart contracts. It is being retired.
- March 2023: ZKsync Era opened to the public with smart contract support.
- June 2023: Matter Labs released the ZK Stack, an open-source framework for launching new chains with the same technology.
- March 2024: Ethereum's Dencun upgrade added blob data, which cut the cost of posting rollup data.
- June 2024: the ZK token launched with an airdrop to users and contributors.
Building on ZKsync Era
Era runs smart contracts written in Solidity and Vyper, the same languages used on Ethereum, and works with common Ethereum wallets. It is compatible with Ethereum but not identical to it. Contracts have traditionally been compiled with a dedicated compiler to Era's own virtual machine, and some low-level behavior differs. Developers should test on Era instead of assuming that code behaves exactly as it does on mainnet. The ZKsync documentation lists the differences.
Era also has account abstraction built in. Every account can behave like a smart contract, which allows features such as paying fees in tokens other than ETH or having an app sponsor fees through a paymaster.
ZK Chains and the ZK Stack
The ZK Stack lets other teams run their own chains using the same proving technology. These chains can connect through shared bridge contracts on Ethereum. The project calls this group of chains the Elastic Network. Examples built with the stack include Abstract and Sophon.
The ZK Token
The ZK token has a total supply of 21 billion. In the June 2024 airdrop, 17.5% of that supply was distributed to eligible wallets. The remaining supply was allocated to ecosystem programs, investors and the Matter Labs team, with investor and team tokens subject to vesting.
ZK is a governance token. Holders can delegate votes and take part in decisions about protocol upgrades and token programs. Transaction fees on ZKsync Era are paid in ETH, not in ZK.
Risks to Understand
- Centralized sequencer: one operator currently orders transactions. If it goes offline, the network can stall.
- Upgrade control: the contracts can be upgraded through governance, and a security council can act in emergencies. Users rely on those parties behaving properly.
- New cryptography: proof systems are complex, and a bug in a circuit or verifier could be serious.
- Operational incidents: in April 2025 a compromised admin key on an airdrop distribution contract let an attacker mint about $5 million in unclaimed ZK tokens. User funds were not affected and the tokens were later returned, but the event showed the risk of privileged keys.
- Bridge risk: funds on any layer 2 depend on the bridge contracts that hold them on Ethereum.
- Competition: Arbitrum, Base, Optimism and other ZK networks such as Starknet, Linea and Scroll all compete for the same users.
Nothing in this article is financial advice.
Key ZKsync Facts
- Developer: Matter Labs
- Type: ZK-rollup on Ethereum
- ZKsync Lite launch: June 2020
- ZKsync Era public launch: March 2023
- ZK token launch: June 2024
- ZK total supply: 21 billion
Track on CoinMarketGuy
The ZKsync price page shows the live ZK price, market cap, supply and chart. For tokens that trade on decentralized exchanges, the DEX page lists active pools with volume and liquidity, and the Ethereum page tracks the asset used for fees on the network.