Scroll aims to extend the abilities of the Ethereum mainnet through the use of zero-knowledge and we will be covering it extensively in this article.

Scroll is an EVM-equivalent zkRollup designed to scale Ethereum, aiming to make blockchain technology more accessible and scalable for billions of users. It leverages zkEVM, a core component that proves the correctness of EVM execution in Layer 2, to increase transaction throughput and reduce fees significantly. This approach allows existing applications and developer tooling to migrate from Ethereum to Scroll without deep modifications or rewrites, ensuring a seamless migration path for developers and users.

Scroll's development is closely connected to the PSE group. The project has been built in the open, with contributions from the community and the PSE team, emphasizing transparency and open-source ethos. This collaboration aims to build a zkEVM that is both secure and robust, with the ultimate goal of advancing Ethereum scaling.

Scroll is built to be community-centric and fully open-source from day one, allowing anyone to understand, audit, and contribute to its development. This open-source approach fosters a culture of transparency and responsibility, ensuring that the platform is secure and robust. Scroll's development is supported by a network of developers, ZK researchers, and community organizers, all working towards building a developer- and user-friendly scaling solution for Ethereum.

Scroll was founded in 2021 with the mission to enhance the scalability of the Ethereum network through its Layer 2 solutions. The company is based in Seychelles and primarily serves users and developers within the blockchain and cryptocurrency sectors. Scroll's innovative approach involves an EVm-equivalent zk-Rollup, which is designed to facilitate near-instant and cost-efficient transactions while maintaining the security features of the Ethereum network.

The founding team of Scroll, including Sandy Peng, Shen Haicheng, and Ye Zhang, leveraged zero-knowledge-proof technology to create a scalable solution for Ethereum. This technology allows transactions to be mathematically proven upon posting to the main Ethereum chain, enhancing security and efficiency. The company's focus on scalability and efficiency is a direct response to the challenges of Ethereum's current infrastructure, which struggles to handle a large number of transactions per second at lower fees.

Scroll's technology, zkEVM, is a type of Layer-2 scaling solution that processes transactions off the main Ethereum blockchain, and then posts proof to the main Ethereum network. This method ensures the authenticity of transactions without the need for re-execution, making it a promising solution for Ethereum's scalability issues. The company's approach to scalability and efficiency has garnered attention and support from several protocols, venture capital firms, and blockchain foundations, including OKX Ventures, Polychain Capital, Bain Capital Crypto, Qiming Venture Partners, and IOSG, among others.

Scroll's commitment to decentralization and community involvement is evident in its operations and future plans. The company has been actively engaging with the Ethereum Foundation and the broader open-source community to develop its zkEVM technology, ensuring compatibility and interoperability with Ethereum's existing infrastructure. Scroll's approach to decentralization extends to its principles of community engagement, aiming to build in an open and community-driven way, seeking values-aligned individuals to contribute to its development.

In summary, Scroll was founded to address the scalability challenges of the Ethereum network using innovative zero-knowledge-proof technology. The company's focus on scalability, efficiency, and decentralization, along with its backing from major investors and its commitment to community involvement, positions Scroll as a significant player in the Ethereum ecosystem.

Before understanding the technical details, let's see why this L2 matters. Scroll stands out as a compelling Layer 2 (L2) solution for Ethereum developers and users for several reasons, despite the crowded L2 space:

• Security-Focused Design: Scroll emphasizes security, using innovations in scaling design and zero-knowledge proofs to build a new layer on Ethereum. This focus on security is crucial for developers and users who prioritize the safety and integrity of their applications and transactions.

• High Accessibility and Responsiveness: Scroll is designed to be more accessible and responsive than Ethereum alone, supporting more users at once. This is particularly beneficial for developers looking to build applications that can scale and handle a large number of transactions efficiently.

• High Activity and Growth: Since its Mainnet launch, Scroll has seen substantial activity, with over 100,000 transactions in just the first week. This level of engagement and growth indicates a growing community and ecosystem around Scroll, which can be a positive sign for developers looking to build on this platform.

• EVM Compatibility: Scroll promises a higher degree of EVM compatibility than previous generations of L2 solutions. This compatibility ensures that developers can leverage their existing Ethereum knowledge and tools while benefiting from the scalability and cost-efficiency improvements offered by Scroll.

• User-Friendly Platform for dApps: Scroll was developed with the vision of creating a user-friendly platform for the full spectrum of decentralized applications (dApps). This focus on usability and versatility makes Scroll an attractive option for developers looking to build a wide range of applications on the Ethereum network.

• Innovation in Scaling Solutions: With more than a dozen Ethereum scaling solutions already available, Scroll differentiates itself by offering a unique approach to scaling. Its innovative use of zero-knowledge proofs and a focus on creating a user-friendly platform for dApps set it apart from other L2 solutions.

In summary, while the Ethereum ecosystem is indeed crowded with L2 solutions, Scroll stands out for its security-focused design, high accessibility and responsiveness, strong investor support, high activity and growth, EVM compatibility, and its vision for a user-friendly platform for dApps. These factors make Scroll a compelling choice for developers and users looking to leverage the scalability and efficiency improvements offered by L2 solutions while ensuring the security and compatibility of their applications.

Scroll's architecture is designed to enhance Ethereum's scalability and efficiency through a combination of Layer 2 solutions and zkEVM technology. It consists of three main components: the Scroll Node, the Roller Network, and the Rollup and Bridge Contracts.

1. Scroll Node: The scroll node is mainly responsible for the construction of Layer 2 network blocks from the user transactions. It commits these transactions to the Ethereum Base Layer and facilitates message passing between Layer 1 and Layer 2. The Scroll Node includes modules like Sequencer, Coordinator, and Relayer (covered below). The Sequencer provides an interface to JSON-RPC and accepts Layer 2 transactions. The Coordinator receives the proof of execution from the newly created block and the Relayer monitors the performance of the bridges and rollups deployed on both the Ethereum mainnet and Scroll.

2. Roller Network: The Roller Network is crucial for generating zkEVM validity proofs, which are essential for proving that transactions are executed correctly. Rollers act as provers in the main network, converting the execution trace received from the Coordinator into circuit witnesses and generating proofs for each zkEVM circuit. These proofs are then aggregated to form a new proof block, ensuring the correctness of transactions on the Layer 2 network.

3. Rollup and Bridge Contracts: These contracts are pivotal for providing data availability for Scroll transactions, verifying zkEVM validity proofs, and enabling users to move assets between Ethereum and Scroll. The Rollup contract receives blocks and state roots from the Sequencer and stores the root state in the Ethereum state with block data from Scroll as Ethereum calldata. Bridge contracts, deployed on both Ethereum and Scroll, allow users to transfer arbitrary messages between Layer 1 and Layer 2, facilitating asset movement and interaction between the two layers.

The interaction between these components is essential for Scroll's operation. The Scroll Node constructs L2 blocks from user transactions and commits them to the Ethereum base layer, ensuring that transactions are processed and recorded. The Roller Network generates zkEVM validity proofs, which are used to verify the correctness of these transactions. Finally, the Rollup and Bridge Contracts provide the necessary infrastructure for data availability, proof verification, and asset movement, allowing for a seamless and secure Layer 2 experience on Ethereum.

The Scroll Node is the core component of the Scroll architecture, facilitating the interaction between applications, users, and the Scroll network. It comprises three key modules: the Sequencer, Coordinator, and Relayer. Each plays a crucial role in processing transactions, generating Layer 2 (L2) blocks, and ensuring the security and efficiency of the Scroll network.

1. Sequencer: The Sequencer acts as the entry point for L2 transactions. It provides a JSON-RPC interface, accepting transactions from the L2 mempool. Every few seconds, the Sequencer receives a batch of transactions executes them, and generates a new L2 block along with a new state root. This process ensures compatibility and security and is based on Go-Ethereum [Geth] implementation.

2. Coordinator: Once a new L2 block is generated by the Sequencer, the Coordinator is notified. It receives the execution trace of this block from the Sequencer and dispatches this trace to a randomly selected Roller from the roller pool for proof generation. The Coordinator's function is to manage the execution trace and facilitate the generation of zkEVM validity proofs, which are essential for verifying the correctness of transactions on the L2 network.

3. Relayer: The Relayer monitors the bridge and rollup contracts deployed on both Ethereum and Scroll. It has two main responsibilities. First, it keeps track of the status of L2 blocks, including their data availability and validity proof, by monitoring the rollup contract. Second, it watches for deposit and withdrawal events from the bridge contracts deployed on both Ethereum and Scroll and relays messages between the two chains. This ensures that assets can be moved seamlessly between Ethereum and Scroll, facilitating a trust-free bridge protocol for ERC-20 assets.

The interaction between these modules is crucial for the operation of the Scroll Node. The Sequencer processes transactions and generates L2 blocks and state roots, which are then validated and proofed by the Coordinator and the Roller Network. The Relayer ensures that these proofs are verified and that assets can be moved between Ethereum and Scroll, maintaining the integrity and security of the network.

The Roller Network plays a pivotal role in Scroll's architecture by generating zkEVM validity proofs, which are crucial for ensuring that transactions are executed correctly on the Layer 2 (L2) network. This process is essential for maintaining the security and integrity of the Scroll network, as it verifies the correctness of transactions without revealing their contents.

Rollers in the Roller Network serve as provers, responsible for generating these proofs. They utilize accelerators such as GPUs, FPGAs, and ASICs to reduce the proving time and cost, making the process more efficient. The workflow of generating a validity proof involves several steps:

1. Conversion to Circuit Witnesses: A Roller first converts the execution trace received from the Coordinator into circuit witnesses. This step is crucial for preparing the data in a format that can be used to generate the proofs.

2. Generation of Proofs: The Roller then generates proofs for each of the zkEVM circuits. These proofs serve as cryptographic evidence that the transactions within a block have been executed correctly according to the rules defined by the zkEVM.

3. Proof Aggregation: Finally, the Roller uses proof aggregation to combine proofs from multiple zkEVM circuits into a single block proof. This aggregation process simplifies the verification process on the Ethereum mainnet, making it more efficient and scalable.

The Coordinator plays a key role in managing this process. It randomly selects a Roller to generate a validity proof for each block trace and can dispatch proofs for different blocks in parallel to speed up the process. After generating the block proof, the Roller sends it back to the Coordinator. Every few blocks, the Coordinator dispatches an aggregation task to another Roller to aggregate these proofs into a single aggregate proof. This aggregate proof is then submitted to the Rollup contract on Ethereum to finalize L2 blocks by verifying the aggregate proof against the state roots and transaction data commitments previously submitted to the rollup contract.

In summary, the Roller Network, through its Rollers, is responsible for generating zkEVM validity proofs, which are essential for verifying the correctness of transactions on the Scroll network. This process, facilitated by the Coordinator, ensures that transactions are executed securely and efficiently, contributing to the overall scalability and security of the Scroll Layer 2 solution.

The Rollup and Bridge contracts are integral components of Scroll's architecture, ensuring data availability for Layer 2 (L2) transactions and facilitating asset and message transfers between Ethereum (Layer 1, L1) and Scroll.

Scroll integrates with the Ethereum base layer through the use of Rollup and Bridge smart contracts, facilitating a trustless bridging protocol for ERC-20 assets and other types of assets. This integration is crucial for enabling seamless and secure cross-layer interactions, allowing users and applications to operate across both Layer 1 (L1) and Layer 2 (L2) environments.

The Rollup contract is responsible for receiving L2 state roots and blocks from the Sequencer. It plays a crucial role in ensuring data availability for Scroll transactions by storing state roots in the Ethereum state and L2 block data as Ethereum calldata. This mechanism leverages the security and decentralization of the Ethereum network to ensure that indexers, including the Scroll Relayer, can reconstruct L2 blocks. Once a block proof establishing the validity of an L2 block has been verified by the Rollup contract, the corresponding block is considered finalized on Scroll. This process ensures that transactions are securely and efficiently processed, contributing to the overall scalability and security of the Scroll network.

Bridge contracts deployed on both Ethereum and Scroll enable users to pass arbitrary messages between L1 and L2, as well as bridge ERC-20 assets in both directions. The Bridge contracts facilitate a trust-free bridge protocol, allowing users to send messages or funds from Ethereum to Scroll by calling a sendMessage transaction on the Bridge contract. The Relayer indexes this transaction on L1 and sends it to the Sequencer for inclusion in an L2 block. Similarly, sending messages from Scroll back to Ethereum uses a similar process on the L2 Bridge contract. This functionality is essential for enabling seamless interaction between the two layers, supporting the development of decentralized applications (dApps) and smart contracts that can operate across both L1 and L2.

In summary, the Rollup contract ensures data availability for Scroll transactions by storing L2 block data and state roots on Ethereum, while the Bridge contracts facilitate asset and message transfers between Ethereum and Scroll, enabling a seamless and secure cross-layer interaction. These contracts are pivotal for the operation of the Scroll network, supporting its scalability and security goals.

The trustless bridging protocol for ERC-20 assets is a key feature of Scroll's integration with Ethereum. This protocol ensures that assets can be securely transferred between Ethereum and Scroll without the need for trusted intermediaries. The Bridge contracts on both Ethereum and Scroll facilitate this process by allowing users to lock their assets on one chain and mint corresponding assets on the other chain. This mechanism is designed to be secure, transparent, and efficient, leveraging the cryptographic proofs generated by the zkEVM and the Rollup contract to ensure that assets are correctly transferred and that no double-spending occurs.

In summary, Scroll's integration with Ethereum through Rollup and Bridge smart contracts enables a secure and scalable Layer 2 solution. The trustless bridging protocol for ERC-20 assets, facilitated by these contracts, supports the development of decentralized applications and smart contracts that can operate across both L1 and L2, enhancing the utility and interoperability of the Scroll network.

Scroll is focusing on enhancing the developer experience (DX) for Ethereum builders by streamlining the process of building on its Layer 2 network. It achieves this through several key initiatives and features designed to make it as seamless as possible for developers to migrate their applications from Ethereum to Scroll, without requiring significant modifications.

Scroll is built to be compatible with Ethereum, ensuring that existing code, dependencies, and tooling work with Scroll out of the box. This compatibility is crucial for developers, as it allows them to leverage their existing knowledge and resources when building on Scroll. The network is designed to feel just like developing on Ethereum, with Scroll gaining its security and speed by executing transactions off-chain and producing cryptographic proof that transactions were executed correctly. These proofs are verified in a smart contract on Layer 1, ensuring that all code executed on Scroll behaves just as if it were executed on Ethereum Layer 1.

To facilitate a smooth transition for developers, Scroll provides a Developer Quickstart guide and a Contract Deployment Tutorial. These resources are designed to help developers get started with building on Scroll quickly and efficiently. The tutorials walk through deploying smart contracts on Scroll, providing a hands-on introduction to the platform. Additionally, Scroll offers several deployed contract addresses for developers to build on, further streamlining the development process.

Scroll introduces several bridging solutions to facilitate asset and message transfer between Ethereum and Scroll, including ETH & ERC20 Token Bridge, ERC721 NFT Bridge, ERC1155 Token Bridge, and The Scroll Messenger. These bridges enable developers to easily move assets and interact across chains, supporting the development of decentralized applications (dApps) that can operate across both Layer 1 and Layer 2 environments. The Scroll Messenger, in particular, allows for cross-chain interaction, enabling more complex and interconnected applications.

Scroll has a strong community of users and builders, with a Discord community of over 500,000 members. This community is a valuable resource for developers, providing real-world feedback and support. Scroll's commitment to building a community that brings together users and builders is part of its strategy to enhance the developer experience, ensuring that developers have access to a supportive network as they build on Scroll.

In summary, Scroll focuses on the developer experience by ensuring compatibility with Ethereum, providing comprehensive documentation and tutorials, introducing robust bridging solutions, and fostering a supportive community. These initiatives aim to make it as easy as possible for developers to build on Scroll, leveraging the platform's scalability and security benefits while maintaining the familiarity and efficiency of Ethereum development tools and practices.

Scroll offers a range of tools and services aimed at making the lives of Ethereum developers easier, focusing on scalability, transaction fee reduction, and compatibility with existing Ethereum tools. Here's a breakdown of the key offerings:

• Layer 2 Scaling Solution: Scroll is a Layer 2 scaling solution for Ethereum, utilizing zkRollup technology. This technology is designed to improve the scalability of the Ethereum network and reduce transaction fees, making it more efficient for developers and users alike.

• EVM Compatibility: Scroll is fully compatible with the Ethereum Virtual Machine (EVM), meaning that existing Ethereum applications and tools can seamlessly work with Scroll without the need for modifications. This compatibility ensures that developers can leverage their existing knowledge and tools while benefiting from the scalability and cost-efficiency improvements offered by Scroll.

• Blockchain Explorer: Scroll provides 3 blockchain explorers - Scrollscan, L2 Scan, and Dora Explorer, allowing developers and users to explore transactions, addresses, and other blockchain data in a user-friendly interface. This tool is crucial for developers to debug, monitor, and understand the state of the blockchain.

• Developer Portal and Documentation: Scroll offers a developer portal where developers can manage their projects and API keys. Additionally, comprehensive documentation and SDKs are available to help developers integrate Scroll into their applications and understand its capabilities.

• Web3 Infrastructure Suite: As part of the OKX Build, Scroll provides a suite of Web3 infrastructure tools designed to support the development and deployment of decentralized applications (DApps) on the Ethereum network. This includes APIs and SDKs that developers can use to build on top of Scroll.

In summary, Scroll offers a comprehensive set of tools and services aimed at enhancing the development experience for Ethereum developers, from scalability and transaction fee reduction to compatibility with existing Ethereum tools, as well as security and compliance support.

The launch of Scroll to Mainnet is a big step forward for Ethereum, making it easier and faster to process transactions. Here's a simpler explanation of what it took to get Scroll ready for Mainnet:

• Two Years of Work: Scroll has been in development for over two years. This long period was needed to build and test the technology thoroughly.

• Testing and Auditing: Before going live, Scroll was tested on three different testnets over a year. This helped find and fix any issues. It also went through security audits to make sure it was safe.

• zkEVM Technology: Scroll uses a technology called zkEVM, which is a type of Layer-2 scaling solution. This technology helps make Ethereum faster and cheaper to use by processing transactions off the main Ethereum blockchain.

• Developer-Friendly: Scroll is designed to be easy for developers to use. It's compatible with the Ethereum Virtual Machine (EVM), so developers can use their existing tools and knowledge.

• Community and Security: Scroll is open-source, meaning anyone can contribute to its development. It also places a high priority on security to protect against attacks.

• Real-World Testing: During testing, Scroll processed over 90 million transactions, showing that it can handle a lot of activity efficiently.

• Future Plans: Scroll plans to make its network more decentralized and secure. It's also working on making it easier for developers to use.

Scroll addresses several technical challenges and has future plans that highlight its commitment to decentralization and community involvement, making it a compelling choice for Ethereum developers and users.

• Scalability and Efficiency: Scroll is designed to address the scalability challenges of the Ethereum network by leveraging zkRollup technology. It aims to provide a scalable solution that maintains low transaction fees and fast finality, which are critical for a seamless user experience.

• Decentralization: Scroll emphasizes decentralization across various aspects, including node operators, provers, and the developer and user community. This commitment to decentralization ensures that the protocol is resilient against censorship or coordinated attacks, aligning with the core values of blockchain technology.

• Innovation and Optimization: Scroll focuses on open research-driven innovation, integrating recent breakthroughs in proof systems, proof aggregation, and ZK hardware acceleration. This approach allows Scroll to work with the Ethereum Foundation and other collaborators to find the best ideas, aiming to produce the most efficient solution.

• Developer-Friendly Solutions: Scroll is committed to providing a developer-friendly experience, ensuring that programs written for the EVM can run on its platform without major changes to the development process. This facilitates a seamless migration path for existing dApps and developer tooling.

• Decentralizing Sequencing Nodes: As Scroll approaches the mainnet, it plans to decentralize the sequencer alongside the prover network. This move is expected to enhance censorship resistance and the robustness of the protocol, further emphasizing its commitment to decentralization.

• Community Engagement and Decentralization: Scroll's approach to decentralization extends to its principles of community engagement. It aims to build in an open and community-driven way, seeking values-aligned individuals to contribute to its development. This includes ZK researchers, ZKP, Go or Solidity developers, and GPU engineers, as well as developer advocates and community organizers.

• Nurturing Developer Engagement: Scroll recognizes the importance of fostering and sustaining developer engagement in the Web3 domain. It prioritizes creating clear, comprehensive documentation and engaging content for developers. Additionally, it actively participates in major conferences, and hackathons, and collaborates with universities and blockchain clubs to support and reward developers.

In summary, Scroll addresses critical technical challenges related to scalability, efficiency, and decentralization, while also committing to future plans that emphasize community involvement and developer-friendly solutions. Its approach to decentralization, innovation, and community engagement positions it as a forward-thinking and developer-centric Layer 2 solution for Ethereum.

In conclusion, Scroll represents a significant advancement in the Ethereum ecosystem, offering a scalable and efficient solution to the network's scalability challenges. Its innovative architecture, which includes the Scroll Node, Roller Network, and Rollup and Bridge Contracts, is designed to enhance transaction processing, ensure data availability, and facilitate seamless asset movement between Ethereum and Scroll. The integration of zkEVM technology ensures that Scroll transactions are as secure as those on the Ethereum base layer, leveraging the security of Ethereum and the mathematical guarantees of zero-knowledge cryptography.

Scroll's commitment to decentralization, as evidenced by its plans to decentralize sequencing nodes and its open collaboration with the Ethereum Foundation and the broader open-source community, underscores its dedication to building a robust and secure Layer 2 solution. The company's focus on developer-friendly solutions and its efforts to address technical challenges such as scalability and security make it a promising player in the Ethereum ecosystem.

As Scroll continues to develop and grow, it remains to be seen how it will impact the broader blockchain and cryptocurrency landscape. However, its innovative approach to scalability, security, and decentralization, combined with its commitment to community involvement and developer support, positions Scroll as a key player in the future of Ethereum and beyond.