zkEVMs Could Change the Layer 2 Landscape
3 min readFeb 21, 2023

Rollup-based layer 2 scaling solutions have soared in popularity since the 2021 bull run when users saw just how expensive transactions could get. Some of these solutions have native tokens, such as Optimism, which experienced a 200% rally in January this year. But, the users are not only gravitating to layer 2 scaling solutions for gains; it’s the low-cost and high speed that makes them so attractive.

Rollups aim to make blockchains faster and cheaper without compromising security and decentralization. Rollups run on top of other blockchains, like Ethereum, to improve their efficiency and scalability. Two popular Rollup-based layer 2 scaling solutions are Optimism and zkSync.

zkSync and Optimism

As described in a Gate Learn article, “Optimism is a solution for Ethereum scaling, dedicated to sharing the workload of Ethereum Mainnet and lowering the cost of on-chain transactions. Optimistic rollups, adopted by Optimism, can run almost all dApps on Ethereum while charging rather low gas fees.”

In comparison, zkSync is described on Gate Learn as a ZK-rollup layer 2 scaling solution “that grants quicker and inexpensive payments compared to Layer-1 protocols on Ethereum.”

Transactions on optimistic rollups are initially assumed as valid upon submission but can later be disputed if challenged by a fraud-proof. The side effect is a significant waiting time for withdrawals from the chain, as much as seven days. In contrast, ZK-rollups use zk-proofs that cryptographically validate each transaction before submission, with delays from minutes to hours.

Both solutions aim to solve similar problems but differ in their approach and outcome. Optimism’s technology is much more compatible with Ethereum dApps. At the same time, zkSync suffers from compatibility challenges due to the complexity of ZK-rollups. However, zkSync has significantly lower transaction fees, faster withdrawals, and better security, scalability, and privacy potential.

The future of layer 2 scaling, one of the world’s largest crypto exchanges, has expressed that “while users have favoured optimistic rollups for some time, new developments, specifically with zkEVMs, may lead ZK-rollups to dominate layer 2 scaling in the future.”

Currently, solutions that utilize optimistic rollups dominate the layer 2 space in terms of total value locked, and this is due to the tech being much more mature. On the other hand, zk-based solutions like zkSync stand to replace optimistic rollups in the future, as they can offer more significant benefits to the users. However, there is still a long way to go in developing ZK-rollups, especially regarding compatibility with existing dApps on Ethereum.

Overall, both solutions currently offer various advantages over Layer 1 Ethereum in terms of user experience. Furthermore, the underlying technologies powering Optimism and zkSync, respectively, can even overlap and complement each other if certain concepts are integrated together. However, zk solutions are expected to become the dominant layer 2 scaling solution.