Layer 2

OP Stack is an open source modular blockchain development framework launched by Optimism to help developers build Ethereum compatible Layer 2 networks. By modularizing functions such as the execution layer, settlement layer, sequencing layer, and data availability layer, OP Stack lowers the barrier to developing Rollup networks and provides a unified technical standard for multi-chain coordination.

Optimism and Arbitrum are both Layer 2 scaling networks built on Ethereum, and both use Optimistic Rollup technology to reduce transaction costs and increase network throughput. However, they differ significantly in technical implementation, governance systems, ecosystem strategies, and developer frameworks. Optimism focuses on developing the OP Stack and Superchain ecosystem, while Arbitrum advances scalability through Arbitrum Orbit and a multi layer Rollup architecture.

Superchain and Polygon AggLayer are both infrastructure solutions designed to address liquidity fragmentation, fragmented user experiences, and cross chain interoperability in the multi-chain blockchain ecosystem. However, they take different development paths. Superchain is driven by Optimism and connects multiple Layer 2 networks through the unified technical standard of OP Stack. Polygon AggLayer connects different types of blockchain networks through aggregated proofs and a unified settlement layer.

Optimism is an Ethereum Layer 2 scaling network built on Optimistic Rollup technology. It is designed to reduce transaction costs, increase transaction throughput, and inherit Ethereum’s security. As blockchain applications continue to scale, Optimism moves large volumes of transactions off chain for processing, then submits the results to the Ethereum mainnet, allowing the network to operate more efficiently.

Optimism Explorer is a blockchain explorer purpose-built for the Optimism network, offering users detailed transaction lookup and address data analysis. It enables real-time tracking of transaction statuses, covering both unconfirmed and confirmed transactions, and shows the final settlement outcomes on the Ethereum mainnet (Layer 1).

Linea donated its core ZK Rollup technology stack to an open-source organization under the Linux Foundation, launching an open-source project called Lineth. This article explains the relationship between Linea, ZK Rollup, Lineth, and decentralized governance in accessible terms, and examines the potential impact of this partnership on the Ethereum Layer 2 ecosystem.

Lineth is an open-source ZK Rollup technology project donated by Linea to the Linux Foundation, covering the execution layer, consensus system, Proof System, and Layer1/Layer2 smart contracts. This article delves into Lineth's technical architecture and explores how ZK Rollup leverages zero-knowledge proofs to boost the efficiency and scalability of Ethereum Layer2.

As Ethereum increasingly shifts toward a Rollup-centric development model, Layer 2 governance and decentralization are drawing growing market scrutiny. By placing its core technology under the Linux Foundation's stewardship, Linea is doing more than just open-sourcing—it marks a fundamental transformation in how Layer 2 ecosystems are governed.

Citrea is a ZK Rollup network that uses Bitcoin as its data availability layer and settlement layer. Through BitVM and Type 2 zkEVM technology, it provides BTC with smart contract and BTCFi capabilities. Compared with traditional Bitcoin sidechains, Citrea places greater emphasis on a “Bitcoin native” architecture, aiming to let BTC support DeFi, stablecoins, lending, and on-chain financial applications without changing Bitcoin’s consensus rules.

The ctUSD Vault is a core stablecoin liquidity module in Citrea’s BTCFi ecosystem. Through stablecoin deposits, on-chain asset allocation, and CTR incentives, it provides foundational liquidity support for the Bitcoin DeFi market. Its goal is to build a more stable on-chain capital flow system within a Bitcoin Layer2 environment.

Citrea uses zkEVM, zero knowledge proofs, or ZK Proofs, and BitVM to provide BTC with smart contract and BTCFi capabilities. Unlike traditional Bitcoin sidechains, Citrea places greater emphasis on a “Bitcoin native” architecture, aiming to bring final security back to the Bitcoin mainnet. Citrea’s Rollup process mainly includes five stages: transaction execution, state batching, ZK Proof generation, data submission, and Bitcoin verification. User transactions are first executed in Layer2 zkEVM. The system then generates state proofs and completes final verification and settlement through BitVM and Bitcoin.

Citrea and Stacks both fall under the Bitcoin Layer2 category, but they differ significantly in their underlying architecture and security mechanisms. Citrea uses ZK Rollup, BitVM, and Bitcoin Settlement to bring final state security back to Bitcoin, while Stacks uses an independent chain and PoX, or Proof of Transfer, to enable smart contract functionality through its own network.

Kaskad is a decentralized lending protocol built on the Kaspa ecosystem and running on Igra EVM Layer2. It allows users to access on-chain liquidity by collateralizing digital assets while keeping exposure to their original assets. The protocol uses an overcollateralized model, dynamic interest rates, a partial liquidation system, and a non-custodial smart contract architecture to provide native DeFi lending infrastructure for the Kaspa ecosystem.

Kaskad’s security model mainly includes Health Factor risk monitoring, Partial Liquidation, the COB Oracle price system, Bounded Governance limits, and smart contract audit mechanisms. These designs aim to reduce bad debt, governance attacks, and price manipulation risks in on-chain lending.

Kaskad and Aave are both decentralized lending protocols built on an overcollateralized model, allowing users to access on-chain liquidity by using digital assets as collateral. However, the two differ clearly in their underlying network architecture, governance model, risk controls, and ecosystem positioning.