Author | Callum@Web3CN.Pro
As the current mainstream Layer2 expansion solution, Rollup has made contributions to Ethereum’s pursuit of scalability. OptimisticRollup and ZKRollup have also been gradually verified by the market. After that, Layer2 expansion began to usher in multiple Rollup directions, and anyone can quickly start their own Rollup by using the SDK and run applications on Rollup at high performance and low cost. In the future Layer2 expansion field, Rollup gradually occupies the dominant position, and the most important thing in this process is to simplify the way developers deploy various types of Rollup.
On June 26th, zkSync launched the modular open source framework ZK Stack for building zk-driven. ZK Stack is a free modular open source framework designed to build custom ZK-supported L2 and L3 (called supernodes) based on the zkSync Era code. Prior to this, the scalability solution OP Stack launched by the Optimism team created a shared, high-quality, fully open-source system for creating new Layer2 blockchains.
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In this article, we will compare the similarities and differences between these two solutions, their respective advantages and disadvantages, and usage scenarios. In the increasingly competitive Layer2 market, who can break through and create greater ecological interoperability?
OP Stack is a standardized, shared, and open-source development stack that supports Optimism and is maintained by Optimism Collective. It includes three design principles: practicality, simplicity, and scalability. As a public product of the Ethereum and Optimism ecosystems, OP Stack consists of many different software components that together form the backbone of Optimism.
Features of OP Stack
OP Stack mainly focuses on creating a shared, high-quality, fully open-source system for creating new Layer2 blockchains. By coordinating shared standards, Optimism Collective can avoid rebuilding the same software in isolation. OP Stack can be viewed as a software component that helps define specific layers of the Optimism ecosystem and can also play the role of a module in existing layers. Although the core of OP Stack currently runs the infrastructure of Layer2 blockchains, OP Stack can theoretically be extended to layers above the underlying blockchain, including tools such as block explorers, messaging mechanisms, and governance systems.
OP divides blockchain into three layers: consensus layer, execution layer, and settlement layer. Then, the three layers are standardized. In terms of specific architecture, the OP Stack can be divided into six layers:
DA (Data Availability Layer): The data availability layer defines the source of raw data based on Layer2 of OP Stack. OP Stack can use one or more data availability modules to obtain its input data. Ethereum DA is currently the most widely used data availability module in the OP stack, but in the future, more and more other chains may be added.
Sequencing Layer: The sequencing layer determines how user transactions on the OP Stack chain are collected and published to the data availability layer module in use. In the default Rollup configuration of OP Stack, sequencing is usually handled by a single dedicated sequencer. Rules defined in the derived layer often limit the sequencer’s ability to retain transactions for a specific period of time. In the proposed future, sequencing will be modular so that chains can easily choose and change the mechanisms that currently control their sequencers.
Derivation Layer: The derivation layer defines how to process the raw data in the data availability layer to form a processed input that is sent to the execution layer via standard Ethereum engine APIs.
Execution Layer: The execution layer defines the state structure within the OP Stack system and provides an entry point to the underlying VM, which is abstracted as an EVM modification or a completely different VM.
Settlement Layer: Used to verify the current transaction result, after Layer2 confirmation, the confirmation information will be sent to the target blockchain for final settlement to obtain data validity.
Governance Layer: The governance layer refers to a set of general tools and processes used to manage system configuration, upgrade, and design decisions.
The goal of OP is to upgrade to a super chain through this architecture. OP Stack deconstructs the various components needed to build a Layer2 chain and packages them as separate modules. Developers can combine the most appropriate modules to create their own Layer2, making it easier and more efficient for developers to implement proprietary chains.
The completion of the Bedrock upgrade represents the complete modular rewrite of the core components of the OP mainnet Rollup architecture and the launch of the first official version of the OP Stack. It is also the next major version of the Optimism network, further narrowing the difference between Optimism and Layer1 Ethereum. The Bedrock version will support the use of multiple proof schemes and multiple clients to attract different developers and projects. In addition, it will keep up with the technical decentralization through different routes while maintaining a decentralized governance structure. This provides a key advantage for OP to achieve a super chain in the future:
- Reduce Network Fees: Optimized data compression strategy eliminates Gas Fees associated with EVM execution when submitting data to L1, reducing additional fees by about 10%;
- Reduce Deposit Wait Time: Introduced support for Layer1 restructuring in node software, and deposits are expected to be confirmed within 3 minutes;
- Improve Proving Modularity: Abstract the Proof System separately from the OP Stack to choose in fault-tolerant proofs or validity proofs such as Zk-Snark;
- Improve Node Performance: Execute multiple transactions at once in a single rollup block, reducing data volume by 15G annually;
- Improve Ethereum Equivalence: Remove multiple deviations from previous versions regarding Ethereum, add support for EIP-1559, chain restructuring, and other Ethereum features on Layer1.
After Bedrock upgrade, not only has Optimism’s Layer2 Rollup been improved, but Optimism has also been upgraded to a superchain. The next significant scalability improvement for the OP Stack is the introduction of the concept of a superchain: a chain network of shared bridging, decentralized governance, upgrades, communication layers, etc., all built on the OP Stack. The launch of the superchain will merge Optimism’s mainnet and other chains into a unified OP chain network, marking an important step towards bringing scalable and decentralized computing to the world.
OP Stack simplifies the process of creating Layer2 blockchains, supporting all Optimism software. As Optimism develops, so will the OP Stack. Coinbase is preparing to launch Base Layer2 later this year, based on OP Stack development, and BNB Chain has announced that the opBNB testnet is built on the OP Stack. The OP Stack currently appears in the form of software behind the Optimism mainnet, and will eventually appear in the form of the Optimism superchain and its governance.
ZK Stack is a free modular open-source framework that aims to build custom ZK-supported L2 and L3 (called superchains) based on zkSync Era code. The core of ZK Stack provides two key features: sovereignty and seamless connectivity. Developers have full code rights and unrestricted autonomy to customize and shape all aspects of the chain. Superchains run independently, relying only on Ethereum Layer1 to ensure their activity and security, while the Superbridge network promotes interconnectivity between each superchain, achieving trustless, fast, and cheap interoperability. Overall, ZK Stack has three features: open source, composability, and modularity.
Characteristics of ZK Stack
- Free: ZK Stack is developed under the fully permissive MIT/ABlockingche open source license, ensuring its availability for free.
- Composable: Chains built with ZK Stack can seamlessly connect in trustless networks, with low latency and shared liquidity.
- Modular: Customize and shape every aspect of your chain, from choosing sorters and data availability modes to defining unique token economics.
- Ultra-low cost: Due to the simplicity of ZK proofs, certain transaction types (e.g., oracle updates) are 1,000x cheaper on ZK Stack than on other aggregation platforms. In addition to the ZK rollup mode, ZK Stack can also use extremely affordable zkPorter accounts for optional scaling where appropriate.
- Battle-tested: The zkSync Era is the most widely adopted ZK rollup on Ethereum, with significant TVL and transaction volume to prove it. With this track record, ZK Stack is a safe choice in terms of security and reliability.
- Future-proof: ZK rollups are the future of Ethereum scaling. Build the right architecture from the start to fully leverage the potential of ZK superpowers.
Upgrading to ZK Stack
ZK Stack is also a significant upgrade for the zkSync core team. From zkSync Era to zkstack, the team’s focus has shifted from building ZK tech to helping numerous teams understand ZK Stack and contribute to it. As more chains are launched, the number of core contributors will increase, making the community the true owner of the zkSync network, especially when building custom chains. Deploying a general DeFi dapp or NFT project on existing chains like zkSync Era will be a simpler process, enabling it to sync and combine with other protocols in the ecosystem.
Furthermore, ZK Stack allows for the creation of sovereign chains without sacrificing interoperability and composability. This will greatly increase the scalability of ZK Stack. Each chain seamlessly integrates into its infinitely scalable ecosystem, supported by shared provers and fractal scaling, cultivating a complete liquidity network. In this ecosystem, users can transfer assets quickly and trustlessly without incurring additional costs. Smart contracts will make cross-chain asynchronous calls, and the chains themselves will have sovereignty, enabling them to join alternative ecosystems and take their on-chain assets with them when they choose to leave.
The ZK Stack team will make modifications to the codebase to make it easier to check out, configure, and deploy ZK Stack instances, with the ultimate goal of one-click deployment.
OP Stack VS ZK Stack
The launch of ZK Stack is not so much a competition with OP Stack as a new situation of multi-chain interaction.
From a technical point of view, ZK Stack’s super-chain maximally reuses Ethereum’s security and consensus methods and can directly rely on Ethereum’s security. Compared with OP’s interaction fraud proof, ZK proof directly verifies state changes, does not need to wait for Ethereum’s underlying state changes, simplifies design, avoids duplicate investment, and improves inter-chain interaction efficiency. In comparison, OP Stack still has a lot of restrictions on asynchronous cross-chain calls: its state changes need to wait for Ethereum’s underlying verification, and fraud proofs also need to wait for confirmation.
In addition, unlike OP Stack’s focus on the transformation of the Layer2 market, ZK Stack wants to include both the Layer2 and Layer3 markets. Although both want to realize a multi-chain empire through inter-chain operability, the Layer3 and multi-chain networks built by ZK Stack are intended to develop highly customized expansion.
From an ecological perspective, OP Stack has the advantage of being the first mover. Shortly after the launch of OP Stack, it received support from many projects. In February of this year, Coinbase announced the launch of the multi-chain Layer2 platform Base based on OP Stack, and will build a super chain with the Optimism Collective. Secondly, OP Stack also received support from BNB Chain. On the evening of June 19th, BSC announced a new expansion solution: opBNB, which is based on the Bedrock version of OP Stack and is compatible with EVM. In addition, many application development teams such as NFT trading market Zora, and the client Magi launched by a16z Crypto are also starting to choose OP Stack to develop application chains.
In comparison, the Layer2 of zkSync itself has not been well established, and there have been compatibility and downtime issues with ZkRoullup. The ecology is mostly domestic dog projects, and there are few supports from well-known large factories and projects. In this respect, zkSync is eager to build Layer3, and cannot convince the market’s recognition.
From the perspective of blockchain scalability, super chains and super scalability are worth paying attention to, but from the current development, the project is still in the early stage. Who can occupy the market with the ecological advantage of OP Stack and the technical advantage of ZK Stack remains to be seen, but despite the differences in technology, details, and opinions, they both have the goal of unlimited scalability. Ethereum’s new round of multi-chain scalable narratives is gradually unfolding.
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