WTF Is… A Zero-Knowledge Rollup

TLDR: Zero-knowledge (ZK) rollups make blockchains faster and more efficient. They do this by moving some of the complex data computation away from the main blockchain, then they bundle together all the actions that people have taken and put them on the main blockchain in one fell swoop. This way, the blockchain can handle more transactions and work better.

In the ever-evolving realm of blockchain technology, a new acronym has been making waves: ZK rollups. For tech entrepreneurs and professionals seeking to stay at the forefront of innovation, understanding the zero-knowledge rollups and their role in the Ethereum Virtual Machine (EVM) is essential. In this article, we'll explore ZK rollups, their mechanics, and their implications for the Web3 economy, while also comparing them to other scaling solutions.

ZK rollups 101: Solving the blockchain trilemma 

Let’s start with the purpose of ZK rollups. In order for blockchain technology to meet the needs of mainstream use cases, it must achieve three objectives: security, decentralization and scalability. Finding the right balance between all of these three qualities poses a fundamental challenge to developers known as the “blockchain trilemma.” 

The catch-22 of the blockchain trilemma is that striving for improvement in one of these aspects can potentially compromise the others. Balancing these three pillars is an ongoing puzzle that blockchain ecosystems grapple with in the quest for optimal performance.

Demystifying ZK rollups

A ZK rollup is a Layer-2 scaling solution, abbreviated as an “L2.” As you might remember, L2s are blockchains built on top of a main blockchain (Layer 1, or L1) to improve the volume and speed of transactions so that the ecosystem can handle more activity.

Read More: WTF Is... Layer 2

How ZK rollups operate

So when do L2s become zero-knowledge rollups? ZK rollups describe a specific type of L2 that operates by relocating data computation off chain while storing transaction data on an L1 network, most commonly Ethereum. 

The critical innovation of ZK rollups lies in the cryptographic verification of data using zero-knowledge proofs

Basically, instead of posting every single transaction on chain, ZK rollups only periodically present valid bundled transaction batches from the L2 network to the L1. The L1 network, which provides security and censorship resistance, is leveraged solely for transaction settlement. To further optimize data handling, rollups employ data compression techniques, thereby reducing the volume of information posted on the L1.

ZK rollups vs. optimistic rollups

Optimistic rollups are another type of L2 scaling solution that differs from ZK rollups. Instead of using ZK proofs, optimistic rollups employ a mechanism that first approves the transactions then allows users to challenge the outcome during a specific time window if there are any discrepancies.

Optimistic rollups have gained traction due to their relative simplicity and lower risk of implementation bugs. Yet, ZK rollups, with their cryptographic validity proofs, continue to earn recognition as a more robust long-term solution for scalability.

Examples of ZK rollups

Several projects are actively working on ZK implementations in the Ethereum ecosystem. These ZK rollups are known as ZK-EVMs because they operate on the Ethereum Virtual Machine. According to the Ethereum Foundation, these ZK rollup projects are in active development:

Polygon zkEVM

Polygon zkEVM is a decentralized ZK rollup operating on the Ethereum mainnet. It employs a zero-knowledge EVM to execute Ethereum transactions, including smart contracts. This approach offers greater transparency and security by utilizing zero-knowledge-proof validations.

Applied ZKP

This project, backed by the Ethereum Foundation, aims to establish a method for generating validity proofs for Ethereum blocks, which could significantly improve the network's efficiency and scalability.


Scroll is developing a native zkEVM Layer 2 Solution for Ethereum. This solution can help improve the throughput and efficiency of the Ethereum network while maintaining compatibility with the Ethereum Virtual Machine.


Taiko is a decentralized platform that offers an Ethereum-equivalent ZK-rollup. It falls under the category of Type 1 ZK-EVMs, providing compatibility with Ethereum and aiming to boost its performance and scalability.


ZkSync 2.0 is an EVM-compatible ZK Rollup project initiated by Matter Labs. It introduces its zkEVM to the Ethereum ecosystem, enhancing its capabilities and making it more scalable.

Bottom line

ZK rollups present developers with an exciting opportunity to drive innovation in the blockchain space. By integrating scaling solutions, Web3 professionals can usher in a new era of blockchain scalability and privacy, making blockchain technology more accessible and versatile.

Read More: WTF Is… ZK Proofs

‍This article and all the information in it does not constitute financial advice. If you don’t want to invest money or time in Web3, you don’t have to. As always: Do your own research.

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