What is a ZK Rollup? The Ultimate Guide (2024)

What is a ZK Rollup? The Ultimate Guide (2024)

Ethereum has been facing a long-standing issue: scalability. As the network grows in popularity and usage, it struggles to keep up with the increasing demand, resulting in slow transaction speeds and high gas fees.

This scalability challenge has been a major barrier to Ethereum's widespread adoption, hindering its ability to support the ever-expanding ecosystem of decentralized applications (dApps).

Enter ZK rollups, a type of layer-2 scaling solution that promises to address Ethereum's scalability woes without compromising on security or decentralization. This innovative technology has the potential to unlock Ethereum's full potential, enabling it to process thousands of transactions per second while maintaining its core principles.

Understanding ZK Rollups

At its core, a ZK rollup is a layer-2 scaling solution that utilizes zero-knowledge proofs (ZKPs) to bundle multiple transactions off-chain and submit a validity proof to the Ethereum mainnet. This process significantly reduces the computational load on the base layer, allowing for higher transaction throughput and lower gas fees.

Zero-knowledge proofs, particularly zk-SNARKs (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge), are the backbone of ZK rollups. These cryptographic techniques allow one party (the prover) to prove to another party (the verifier) that a statement is true without revealing any additional information beyond the validity of the statement itself.

In the context of ZK rollups, this means that the rollup operator can prove that a batch of transactions is valid without revealing the details of those transactions to the mainnet. This not only enhances privacy but also reduces the amount of data that needs to be stored on the Ethereum blockchain.

Here's a step-by-step breakdown of how ZK rollups work:

  1. Users submit transactions to the ZK rollup contract deployed on the Ethereum mainnet.
  2. The rollup operator aggregates these transactions off-chain into a batch.
  3. The operator generates a validity proof (using zk-SNARKs) for the batch of transactions.
  4. The proof, along with the state root of the rollup, is submitted to the mainnet contract.
  5. The mainnet contract verifies the proof and updates the state root accordingly.
  6. Users can withdraw their funds from the rollup contract by providing a Merkle proof of their inclusion in the state root.

For a deeper technical dive into ZK rollups, refer to the official Ethereum documentation: ZK rollups.

ZK Rollups vs Other Scaling Solutions

While ZK rollups have emerged as a promising scaling solution, they are not the only option available. Other notable scaling approaches include optimistic rollups and sidechains.

Optimistic rollups, like ZK rollups, process transactions off-chain and submit batches to the mainnet. However, instead of using zero-knowledge proofs, they rely on a fraud-proof mechanism. Transactions are assumed to be valid unless challenged within a specified time frame. If a challenge is successful, the fraudulent transaction is rolled back, and the challenger is rewarded.

Sidechains, on the other hand, are separate blockchain networks that run parallel to the Ethereum mainnet. They have their own consensus mechanisms and can process transactions independently. Sidechains are connected to the mainnet via a two-way peg, allowing assets to be transferred between the two chains.

While optimistic rollups and sidechains have their merits, ZK rollups offer several advantages:

  • Faster transaction finality: With ZK rollups, transactions are considered final as soon as the validity proof is verified on the mainnet. In contrast, optimistic rollups have a challenge period during which transactions can be disputed, leading to longer finality times.
  • Higher security: zk rollups inherit the security of the Ethereum mainnet thanks to the validity proofs. Sidechains, while offering high throughput, have their own security models, which may not be as robust as the mainnet.
  • Lower gas fees: By bundling multiple transactions off-chain, zk rollups significantly reduce the gas fees required per transaction. This is particularly beneficial for users looking to perform small-value transactions.

For a more detailed comparison of rollups and sidechains, check out the Infura Blog: Sidechains vs Rollups and the Ankr Blog: Rollups vs Sidechains: Benefits Explained and What to Build in 2024.

The Current Landscape of ZK Rollups

The zk rollup ecosystem has been growing rapidly, with several notable projects leading the charge. Here are a few of the most prominent ones:

  1. zkSync: Developed by Matter Labs, zkSync is a zk rollup solution that supports Ethereum-based payments and token transfers. It utilizes a zk-SNARK based protocol called "zkPorter" to achieve high throughput and low latency.
  2. Loopring: Loopring is a zk rollup-based decentralized exchange (DEX) protocol. It enables high-speed, low-cost trading while maintaining the security and non-custodial benefits of decentralized exchanges.
  3. Starkware: Starkware is a company that develops zk-SNARK based scaling solutions. Their flagship products, StarkEx and StarkNet, enable scalable and privacy-preserving transactions on Ethereum.

These projects have been making significant strides in advancing zk rollup technology. For instance, zkSync recently launched its mainnet, bringing its vision of scalable and low-cost payments closer to reality. Loopring has processed over $1 billion in trading volume, demonstrating the potential of zk rollups in powering high-throughput applications.

However, zk rollups are still a relatively new technology, and there are challenges that need to be overcome. One of the main limitations is the computational complexity of generating zk-SNARKs, which can lead to longer processing times compared to other scaling solutions. Additionally, zk rollups currently have limited smart contract functionality, which restricts the types of applications that can be built on them.

Despite these challenges, the zk rollup community is actively working on solutions. Advancements in zk-SNARK algorithms and the development of more efficient proof systems are expected to improve the performance of zk rollups over time. Moreover, projects like StarkNet are working on bringing general-purpose smart contract capabilities to zk rollups, opening up new possibilities for developers.

For more examples of recent developments in the zk rollup space, refer to the Token Metrics blog: Top Ethereum Zk-Rollup Projects.

Building with ZK Rollups

As ZK rollups gain traction, more developers are looking to build on this promising technology. Platforms like thirdweb are making it easier than ever for developers to get started with zk rollups, offering a suite of tools and services to streamline the development process.

Getting Started for Developers

To begin building on ZK rollups, developers can leverage thirdweb's powerful SDKs and intuitive dashboard. Here's a quick overview of the steps involved:

  1. Choose a ZK rollup network: Select the zk rollup network you want to build on, such as zkSync or StarkNet. Thirdweb supports a wide range of EVM-compatible chains, making it easy to deploy contracts on your preferred network.
  2. Set up your development environment: Install the necessary dependencies and configure your development environment. Thirdweb provides detailed documentation and guides to help you get set up quickly.
  3. Write your smart contracts: Develop your smart contracts using Solidity or the programming language supported by your chosen zk rollup network. Thirdweb offers pre-built contract templates and extensions to accelerate your development process.
  4. Deploy your contracts: Use thirdweb's intuitive dashboard or CLI to deploy your contracts to the zk rollup network. Thirdweb handles the complexity of interacting with the network, making deployment a breeze.
  5. Interact with your contracts: Once your contracts are deployed, you can interact with them using thirdweb's SDKs. Thirdweb provides SDKs for various programming languages, including JavaScript, Python, and Go, allowing you to integrate your contracts seamlessly into your applications.

Here's an example of how you can deploy a contract on zkSync using thirdweb:

import { ThirdwebSDK } from "@thirdweb-dev/sdk";

const sdk = new ThirdwebSDK("zksync-era");

const contractAddress = await sdk.deployer.deployContract({
  name: "MyContract",
  bytecode: "0x...",
  abi: [...]

In this code snippet, we initialize the ThirdwebSDK with the zksync-era network, indicating that we want to deploy our contract on zkSync. We then use the deployer module to deploy our contract, providing the necessary details such as the contract name, bytecode, and ABI.

Thirdweb abstracts away the complexities of interacting with the zk rollup network, allowing developers to focus on building their applications. With thirdweb, deploying contracts and managing transactions on zk rollups becomes a straightforward and efficient process.

References and Resources

For more insights on building with zk rollups and examples of successful projects, check out the following resources:

The Future of zk Rollups

As zk rollups continue to evolve and mature, they hold immense potential for transforming Ethereum's scalability landscape and driving mainstream adoption of decentralized technologies.

Impact on Ethereum's Scalability and Adoption

Zk rollups have the power to significantly enhance Ethereum's scalability, enabling the network to process thousands of transactions per second without compromising on security or decentralization. This scalability boost is crucial for the widespread adoption of Ethereum-based applications, as it allows for faster and cheaper transactions, making them more accessible to a broader user base.

Moreover, zk rollups can help alleviate the congestion on the Ethereum mainnet, reducing gas fees and improving the overall user experience. As more transactions are processed off-chain through zk rollups, the mainnet can focus on high-value, complex transactions, ensuring optimal utilization of its resources.

Upcoming Developments

The zk rollup ecosystem is constantly evolving, with numerous projects working on advancing the technology and expanding its capabilities. Some notable upcoming developments include:

  • Improved proof systems: Researchers are exploring more efficient proof systems, such as zk-STARKs (Zero-Knowledge Scalable Transparent Arguments of Knowledge), which have the potential to further reduce the computational costs associated with generating and verifying proofs.
  • Enhanced interoperability: Efforts are underway to improve the interoperability between different zk rollup networks and the Ethereum mainnet. This will enable seamless asset transfers and communication between various zk rollup solutions, fostering a more interconnected ecosystem.
  • Expanded smart contract functionality: Projects like StarkNet are working on bringing general-purpose smart contract capabilities to zk rollups, allowing developers to build a wider range of applications on these scalable networks.

The Broader Ecosystem

Zk rollups are not just transforming Ethereum; they are also playing a significant role in the broader blockchain ecosystem. As more projects adopt zk rollup technology, we can expect to see a proliferation of scalable, privacy-preserving applications across various domains, such as decentralized finance (DeFi), gaming, and digital identity.

Furthermore, the advancements in zk rollups are driving innovation in other areas of cryptography and computer science. The research and development surrounding zero-knowledge proofs have far-reaching implications beyond blockchain, with potential applications in fields like privacy-preserving computation and secure multi-party computation.


In this comprehensive guide, we have explored the world of zk rollups, a groundbreaking layer-2 scaling solution that aims to address Ethereum's scalability challenges. We have delved into the technical aspects of how zk rollups work, compared them with other scaling solutions, and highlighted the current landscape of zk rollup development.

For developers, zk rollups present an exciting opportunity to build scalable, secure, and privacy-preserving applications on Ethereum. Platforms like thirdweb are making it easier than ever to get started with zk rollup development, offering a suite of tools and services to streamline the process.

As the zk rollup ecosystem continues to evolve and mature, we can expect to see a wave of innovation and adoption in the coming years. With their potential to unlock Ethereum's scalability and drive mainstream adoption of decentralized technologies, zk rollups are poised to play a pivotal role in shaping the future of blockchain.

We encourage developers to explore zk rollup technology further and consider building on this innovative platform. By contributing to the development and advancement of zk rollups, you can be part of the movement that is revolutionizing Ethereum and the broader blockchain ecosystem.

The future is bright for zk rollups, and the possibilities are endless. As a developer, you have the power to shape this future and create applications that can transform industries and improve lives. So, dive in, experiment, and innovate – the world of zk rollups awaits!

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Stay tuned to the thirdweb blog for the latest updates, guides, and insights on zk rollups and other cutting-edge developments in the world of blockchain and decentralized technologies.