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zkEVMs — What’s The Hype All About?

●   6 min

zkSync is set to launch the first-ever zero-knowledge Ethereum Virtual Machine (or zkEVM) on 28th October, which is set to change the Layer 2 scene on Ethereum.

What’s so special about this technology, and is it really the future of Ethereum scaling?

Here’s everything you need to know about zkEVMs.

What is a zkEVM?

A zkEVM can be broken down into 2 major components:

#1 Zk (Zero-Knowledge) rollups

A rollup is a type of scaling technology that moves both data and computation off-chain, on a Layer 2 that is built on top of a Layer 1.

Multiple transactions on this Layer 2 are then bundled together and posted to the Layer 1, which is the Ethereum network in this case.

Since there is only one transaction that is posted on the Layer 1, the transaction fees are spread across all of the transactions that are bundled together, instead of just one.

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This will help to effectively lower the transaction fees on the Layer 2!

On the Ethereum network, there are 2 main types of rollups:

  1. Optimistic rollups
  2. Zero-Knowledge rollups

Zk-rollups generate zero-knowledge proofs, where the base layer (Ethereum) requires minimal information on the transaction and it will be verified as a valid transaction.

This is done via validity proofs, which are required to finalise transactions on the base layer.

#2 Ethereum Virtual Machine

The second component of a zkEVM is the Ethereum Virtual Machine (EVM). This is an environment that was built for smart contracts to run on the Ethereum network.

If you’ve heard of EVM-compatible networks, this means that these networks are compatible with the Ethereum Virtual Machine.

Some of these include Layer 1s that are separate from Ethereum, such as:

  • BNB Smart Chain
  • Avalanche
  • Fantom
  • Cronos
  • Klaytn

Meanwhile, there are Layer 2s built on top of Ethereum that are EVM-compatible, which include:

  • Polygon
  • Arbitrum
  • Optimism

Arbitrum and Optimism are examples of optimistic rollups, which is the other type of rollup technology used on Ethereum.

To run the EVM, developers will need to be familiar with the Solidity programming language.

Moreover, they are able to port their code from EVM-compatible network to another rather easily, since they are using the same language.

Combining them together

When we combine both of these elements together, here is what we get:

“A Layer 2, zero-knowledge rollup scaling solution that is compatible with the Ethereum Virtual Machine.”

In a podcast episode on Bankless, zkSync’s Chief Product Officer, Steve Newcomb, mentioned the 5 main components of a zkEVM:

  1. General purpose
  2. EVM-compatible
  3. Open-source
  4. Supported by a token model that most people have consensus that is effective
  5. Allows developers to use Solidity

Why do we actually need zkEVMs?

Since we already have optimistic rollups, and Ethereum is set to scale even more with sharding, is there really a use case for zkEVMs?

Here are some of the reasons why we need this technology:

#1 Rollups help to reduce congestion on the Ethereum network

While Ethereum is arguably the best smart contract platform with the highest amount of Total Value Locked (TVL), it is currently not scalable enough.

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The blockchain trilemma is used to describe where 1 out of the 3 major components of every blockchain network has to be sacrificed.

Ethereum chose security and decentralisation, and as a result, it sacrificed the scalability of its network.

Ethereum’s transaction per second (tps) is roughly around 15, which results in the network being congested in periods of high demand.

This is where a lot of transactions are being posted at the same time, but only a few can be processed due to Ethereum’s low tps.

As a result, Layer 2 scaling solutions have been built on top of Ethereum to ease the load off the Layer 1 network.

While Ethereum is set to have a major scalability upgrade when sharding occurs, Vitalik Buterin has mentioned the need for Layer 2s to further improve Ethereum’s scalability.

In his ideal world, Vitalik hopes to see that users would have already adapted to a rollup-centric world by the time sharding is available on Ethereum.

#2 Zk-rollups are superior to optimistic rollups

The most popular rollups on the Ethereum network are Arbitrum and Optimism, both of which are optimistic rollups that have captured the lion’s share of the L2 market.

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One advantage of optimistic rollups is that they are much less complex, making them easier to implement.

However, optimistic rollups are not the best way to scale. This is because optimistic rollups operate on the assumption that all of the transactions on their network are valid.

The only way that someone can challenge the validity of a transaction is by submitting a fraud proof during a challenge period, which is around 1 week.

If no fraud proofs are posted, all transactions are deemed valid and will be posted on the Ethereum network after the challenge period ends.

Due to how optimistic rollups function, it takes a longer time to withdraw funds from these L2s back to Ethereum.

In contrast, funds from a zk-rollup can be transferred immediately to the Ethereum network once the zk-rollup smart contract verifies the validity proof.

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In Vitalik’s blog post, he mentioned that zk-rollups are superior to optimistic rollups in most use cases, but the ZK-SNARK technology is not fully developed yet.

Furthermore, he also mentioned in another article that zk-rollups will be the eventual Endgame for Ethereum, since they are more elegant, scalable and secure.

As a result, zk-rollups seem to be superior compared to optimistic ones!

#3 The current zk-rollups are not EVM-compatible

There are a few Layer 2s on Ethereum that utilise zk-rollup technology, including:

  1. Loopring
  2. ZKSpace
  3. Aztec Network
  4. zkSync

However, none of these technologies is EVM-compatible, which affects its attractiveness for developers to create decentralised applications (DApps) on their network.

For example, we can see that the TVL on Loopring has been steadily declining in 2022.


There are challenges of implementing an EVM-compatible zk-rollup, particularly since they require a lot of computational power.

Due to these limitations in the technology, zkEVMs were only expected in 2023.

Even Vitalik Buterin was surprised at how fast zkEVMs are being developed, with the first one set to come out next week!

Who’s in the race to launch a zkEVM?

Here are the 4 companies that are planning to launch their own zkEVM.

#1 zkSync

zkSync has previously launched a fully functional zk-rollup Layer 2, but it is currently not EVM-compatible.

They have announced that zkSync 2.0 will be launched on 28th October, which will be the first-ever fully functioning zkEVM.

Furthermore, the Uniswap community has overwhelmingly voted for its protocol to be deployed on zkSync, which is a huge vote of confidence.

Uniswap is the second largest decentralised exchange on Ethereum, with roughly $4.5 billion Total Value Locked (TVL).

#2 Polygon

Polygon is a Layer 2 scaling solution for Ethereum, and it already operates other solutions like its sidechain that utilises Proof-of-Stake.

Polygon previously announced its intention to build a zkEVM in July,

and they recently launched its public testnet a few days ago.

Their zkEVM should be expected to launch in 2023.

#3 StarkNet

StarkNet (by StarkWare) is slightly unique as it uses the Cairo programming language, and not Solidity.

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While StarkNet is not fully EVM-compatible, the Nethermind team is building the Warp technology that can convert code from Solidity into Cairo.


Nethermind recently managed to ‘warp’ Uniswap onto its network, and other DApps could be warped in the near future.

Once more of them are warped to StarkNet, this could bring even more users to this Layer 2 solution.

#4 Scroll

Scroll seems to have the least hype over its solution, which could possibly be due to its lower funding as compared to the other companies.

The team recently upgraded its Pre-Alpha testnet, which now allows smart contracts to be deployed on the network.

There are no further updates, and their mainnet may be launched in 2023 as well.

Closing Thoughts

For a blockchain network to become mainstream, it needs to be scalable enough to meet the demands of multiple users.

It is heartening to see that developers are constantly building and improving on the Ethereum network to finally solve its scalability issues, and the zkEVM is definitely the way forward.

This technology could finally be the answer to reducing gas fees on the Ethereum network!

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