What Are ZK Rollups?

By Tokenize Xchange
March 28, 2023

Two of the biggest players in Ethereum gaming: Immutable X and Polygon have announced their partnership to establish a new network designed exclusively for Web3 gaming, powered by zkEVM technology, and new EVM-compatible ZK rollups powered by Polygon technology. So, what are ZK rollups? This article, Tokenize Xchange – Crypto Exchange Platform Singapore will explain ZK rollups and introduce you to 5 ZK rollup projects to watch in 2023. 

understanding zk rollups

What are Rollups?

As we mentioned in the article Layer 2 Blockchain And Scaling Solutions, rollups are one of the scaling solutions with the ability to compute and improve transaction processes besides Sidechain and State channels. Rollups refer to splitting transactions off the main chain, wrapping them in a single batch, creating proof, and then submitting it to the base layer (Layer 1). 

After so many transactions are combined into a single transaction, the “gas” fee is reduced to only one transaction, which is shared among all parties involved which makes them a cheaper option. 

There are two types of rollups: optimistic rollups and zero-knowledge rollups (ZK rollups). Both target solving the blockchain scalability issue, but each has its own pros and cons.

>>> Click HERE to learn more about Optimistic rollups

Understanding ZK proofs (Zero-knowledge proofs)

Zero-knowledge proofs (ZK proofs) refer to the method of digital verification in which the prover can demonstrate that they have access to information without necessarily exposing the underlying information

For example, a verifier provides a prover with the hash H and requests that the prover show proof that it owns the secret data hashing to H. The prover generates a zero-knowledge proof to persuade the verifier that it possesses the data that hashes to H without giving the data to the verifier.

The concept was invented in 1985 by MIT students Shafi Goldwasser and Silvio Micali. Since then, ZK proofs have been widely applied, with real-world applications in creating privacy and security-oriented technology. Clearly, ZK proofs increase cryptography and allow for the creation of privacy-focused cryptocurrencies such as Zcash.

Moreover, ZK proofs provide the basis for building rollups, which dramatically improve the scalability and performance of blockchain networks.

So what are ZK rollups (zero-knowledge rollups)?

ZK rollups use their zero-proof technology to provide regular validity proofs to connected smart contracts on the parent network, certifying the accuracy of the layer-2 network transactions. Because of the dependence on zero-proofs, the volume of shared transaction data is reduced, making ZK rollups privacy-focused by default.

Apart from privacy, ZK rollups free users from waiting many days before withdrawing funds from the layer-2 solution which is the major limitation of the technology’s infancy. 

ZK rollup projects

Below are 5 ZK rollups projects and coins to watch for in 2023:

  • Mina Protocol ($MINA)
  • Immutable X ($IMX)
  • Loopring ($LRC)
  • Polygon ($MATIC)
  • Dusk Network ($DUSK)

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Zk Rollups vs Optimistic Rollups

So, the basic difference between ZK Rollups and Optimistic Rollups is their cryptographic proof. While Optimistic Rollups employs the fraud-proof method, ZK Rollups adopts the zero-knowledge proof that we have mentioned above.  

On-chain processing speed

After an optimistic rollup batch is submitted, there is an amount of time known as a challenging period during which anybody can contest the outcome of a rollup transaction by generating a fraud-proof. If the fraud-proof is successful, the roll-up protocol re-executes the transaction and updates the rollup’s state. On the other hand, if optimistic rollup state transitions are not contested before the end of the challenge period, the batch of transactions is deemed legitimate and accepted to be recorded to layer 1.

Since there is no waiting period during which the transaction’s legality may be questioned, zero-knowledge rollups are recorded to the underlying blockchain ledger faster than optimistic roll-up transactions. Hence, the advantage of zero-knowledge rollups over the optimistic ones is the speed of on-chain processing. 


Because of the elimination of the validity proof calculation, optimistic rollups are now more scalable. A program that utilizes optimistic rollups will be less affected by a great increase in transactions, whereas a zero-knowledge rollup solution may be substantially slower.

Smart contract operation

Optimistic rollups can directly run smart contracts on the main blockchain. ZK Rollups, however, cannot execute smart contracts on the main chain.

Immutable announced a partnership with Polygon for the new zkEVM Ethereum gaming network

Polygon and Immutable, two Ethereum scaling heavyweights, are collaborating to establish a new network designed exclusively for Web3 gaming, powered by Polygon’s expected zkEVM technology. The association intends to create a solution for businesses “that accelerates time-to-market and gives them access to one of the largest and most liquid for end consumers.”

zkEVM is an EVM-compatible virtual machine using zero-knowledge rollups to verify and execute smart contracts. It is sometimes referred to as the “Holy Grail” of Ethereum scaling. This technique enhances transaction speeds and lowers gas fees while leveraging the Ethereum blockchain’s battle-tested security.

Designed to make developing web3-enabled games faster, easier and less risky, Immutable zkEVM will allow both large game studios and independent developers to build high-quality games that support true asset ownership.” According to Immutable.com

“By combining the number one Web3 gaming platform – currently serving hundreds of game studios and millions of players – with Polygon’s best-in-class zkEVM technology, we are building an Ethereum-centric gaming ecosystem that is poised to take Web3 mainstream and bring digital ownership to millions of people around the world,” said Robbie Ferguson, Immutable president, and co-founder. “Billions of dollars of skins are sold each year with no rights for players – we’re changing that so players are in control, and ownership is the expectation.”

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Bottom line

Among different scaling methods presented to expand and test the capabilities of current blockchains, the ZK rollups method is an outstanding name. Due to their potential to improve user experience and solve the issues of the digital asset ecosystem, ZK rollup projects are drawing investors’ attention as interesting investment prospects. If you want to learn more about blockchain technology innovations, don’t forget to follow Tokenize Xchange – Singapore Crypto Trading Platform


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