Ethereum is a powerful but overloaded network. Layer 2 solutions (L2) alleviate the load from the main layer, reducing fees and increasing speed. Among them, three projects stand out: Arbitrum, Optimism, and zkSync. Let’s figure out what unites them and what distinguishes them.
What is Layer 2?
Layer 2 is a solution that operates on top of Ethereum (or another L1), which processes transactions separately and then publishes their results on the main network. This is:
-reduces the load on Ethereum.
-cheaper and faster for users.
-maintains the security of Ethereum L1.
L2 is divided into two categories: Optimistic Rollups and ZK-Rollups.
Optimism and Arbitrum — Optimistic Rollups
Both use an optimistic model: they assume that all transactions are honest until someone proves otherwise.
Optimism
The first mass Optimistic Rollup.
Simple architecture, compatible with EVM (Ethereum Virtual Machine).
Rapid adoption, supported by a large number of projects.
Uses Canonical Chain — the native bridge between L1 and L2.
Arbitrum
More technologically advanced Optimistic Rollup.
Uses its own VM (Arbitrum Virtual Machine) with flexible configuration options.
Recognized as the leader in TVL among L2.
Supports Arbitrum One and Arbitrum Nova (for gaming/social applications).
The main downside of Optimistic Rollups is the withdrawal delay (up to 7 days) due to the 'challenge period'.
zkSync — next-generation ZK-Rollup
ZK-Rollups use Zero-Knowledge Proofs — cryptography that proves the correctness of transactions without the need to disclose all data.
zkSync Era
The first ZK-Rollup with EVM support (zkEVM).
Almost instant transaction confirmations.
High level of security — everything is verified mathematically.
Great UX, especially for payments and DeFi.
The main challenge of ZK-Rollups is technical: creating ZK proofs requires significant computation, but they are becoming more efficient.
Who is suitable for what?
Optimism — for quick integration and simplicity.
Arbitrum — for large-scale applications with flexible requirements.
zkSync — for those who want maximum security and advanced cryptography.
The future belongs to hybrids
The world of Ethereum L2 is rapidly evolving. In the coming years, we will see:
Mass adoption of ZK technologies.
Growth of cross-L2 interactions.
Simplifying UX — users will not know where they are: L1, Arbitrum, or zkSync. Everything 'just works'.