The Ultimate Guide to zkEVM: A Comprehensive Comparison of 6 zkEVM Solutions

Original Author: @thirdweb

Original compilation: @BitalkNews

zkEVM is bringing Ethereum to the masses. But with so many options, which one is the best? We compare PolygonzkEVM (+ 2.0), zkSync Era, Linea, Scroll and Taiko, your ultimate zkEVM guide.

A quick recap:

zkEVM is the layer 2 network that processes transactions and sends proofs back to Ethereum. They use zero-knowledge proofs (ZK) and EVM compatibility to reduce computational load and improve scalability on Ethereum (L1) without sacrificing security or decentralization.

But not all zkEVMs are the same, there are different types of zkEVMs:

Vitalik has a great framework showing the pros and cons of each type, from Ethereum equivalent (type 1) to EVM compatible (type 4). The main tradeoff is EVM compatibility vs. performance:

So which zkEVM is the best? We compared the most popular options:

→ Polygon zkEVM (+ 2.0)

→ zkSync Era

→ Line

→ Scroll

→ Taiko

Let’s break them down.

Polygon 2.0 (zkEVM Validium)

In June 2023, Polygon Labs proposed to upgrade Polygon PoS to zkEVM validium.

Polygon PoS has a strong ecosystem:

→ 2B+ TVL (assets on the chain)

→ Tens of thousands of dApps

→ about 2.5 million transactions/day

Migrating PoS to zkEVM validium will retain its network effects and low fees without affecting its existing applications, user and developer experience. But, doesn’t Polygon already have a zkEVM?

Polygon sees 2.0 (its proposed zkEVM validium) as a lower-cost, higher-throughput version of its Polygon zkEVM Rollup.

Rollups uses Ethereum to publish transaction data and verify proofs, inheriting its security and decentralization. But there are trade-offs:

The disadvantage of Rollup is that publishing transaction data to Ethereum is expensive and limits throughput. Validium provides security guarantees similar to Rollup (ZK proofs guarantee transaction validity), but transaction data is provided off-chain.

This gives Validiums two main advantages over Rollup:

• Fees are lower because they don’t consume expensive Ethereum Gas (i.e. block space to store transaction data)
• Higher scalability, as the throughput of Rollups is limited by the amount of transaction data that can be published to Ethereum

The tradeoff for Validium is that they must ensure transaction data availability outside of Ethereum, which can be challenging. But Polygon PoS’s existing more than 100 validators can serve as a highly secure and reliable guarantee of data availability.

So why use Polygon zkEVM?

Polygon zkEVM

Polygon zkEVM is a type 3 ZK-Rollup. It aims to be equivalent to the EVM - meaning greater scalability (by preserving EVM opcode compatibility) when working with existing Ethereum tools and clients.

Currently, Polygon PoS (2.0) and Polygon zkEVM rollup are the two public networks of the Polygon ecosystem. This is still the case after the upgrade: one as Rollup and the other as Validium.

But why not just deprecate Polygon zkEVM?

Polygon 2.0 and Polygon zkEVM complement each other: Polygon zkEVM (Rollup) has slightly higher fees and slightly lower throughput, but offers the highest level of security. This is best suited for applications that handle high-value transactions (such as DeFi).

On the other hand, Polygon 2.0 (zkEVM validium) will provide the highest scalability. This is best for applications with high transaction volume and low fees (e.g. Web3 games, social)

The mainnet launch of Polygon zkEVM is in March 2023, and the current TVL on the network is about $54 million. Built on Polygon zkEVM:

zkSync Era

The zkSync Era is currently Type 4 zkEVM, though it may add EVM bytecode compatibility over time. Era (its mainnet) was built by Matter Labs and will go live in March 2023, with a current TVL of about $450 million and a transaction volume of 27 million in the past month.

The goal of zkSync is not EVM equivalence, but to increase proof generation speed through its custom virtual machine (VM). It natively supports Ethereum cryptographic primitives, simplifies testing of Hardhat plugins, and improves user experience through native account abstractions.

zkSync Era uses its LLVM compiler to convert Solidity, Vyper, and Yul code into executable code on the zkSync VM, with Rust and C++ compatibility planned for the future. It has a powerful L1-L2 contract messaging system that helps developers pass data between contracts on Ethereum and zkSync.

The upcoming zkPorter integration in zkSync will give users the choice of:

• High security zkRollup account, compared with Ethereum, the fee is reduced by about 20 times

• zkPorter accounts with stable transaction fees and different security models, allowing for a flexible user experience

For data availability, zkSync Era publishes state diffs instead of transaction inputs - providing data compression and integration with zkPorter.

As the only type 4 zkEVM on this list, its custom virtual machine enables some features (and greater scalability) on zkSync Era.

For example: zkSync Era enhances the developer experience by natively supporting account abstraction using its custom virtual machine. However, EVM equivalent chains cannot natively support account abstraction, they are implemented through Ethereum’s ERC-4337.

The downside of type 4 zkEVM is the lack of compatibility - the development process needs to be adjusted to build applications on top of zkSync. Build on zkSync Era:

Line

Built by ConsenSys (creators of MetaMask, Truffle, and Infura), Linea is currently a Type 3 zkEVM. With a native MetaMask wallet and Truffle developer kit integration, its Alpha mainnet launches in July 2023 and has amassed a TVL of $50 million.

Linea is unique in its ability to execute unaltered native bytecode according to the Ethereum Virtual Machine specification. The goal is to provide a Type 2 zkEVM in the future, ensuring near-full compatibility with Ethereum while maintaining scalability.

Linea does not use transpilers or custom compilers. It directly uses Solidity compiled bytecode to generate ZK proofs for smart contracts, reducing the risk of bugs and hacks. For users, this means Ethereum-like security with much lower transaction costs.

Build on Linea:

Scroll zkEVM

Scroll is a zk-Rollup on Ethereum, currently a type 3 zkEVM, and plans to transform into a type 2.

Its long-term goal is to prioritize EVM compatibility and decentralization over ZKP rapid generation, thus moving to Type 1 zkEVM.

A successful Type 1 is the ultimate form of EVM compatibility, decentralization, and scalability—essentially replicating Ethereum L1. But as we have seen with Ethereum itself, this is much harder to achieve.

Currently, Scroll’s alpha testnet is a type 3 zkEVM, which is open to the public. Build on Scroll:

Taiko

Similar to Scroll, Taiko is a generalized zk-Rollup that aims to be a Type 1 native zkEVM. Taiko took a different approach than Scroll to becoming a Type 1, prioritizing decentralization over speed from the start:

Scroll is gradually enhancing EVM compatibility (starting with type 3 testnets) and making its orderers and provers more decentralized when mainnet launches. Although ZKP generation is slower, Taiko decentralizes these components from the beginning and maximizes EVM compatibility.

Taiko’s Type 1 testnet is currently available. Build on Taiko:

Use Vitalik’s framework: → Taiko: Type 1 (testnet launch) → Polygon zkEVM: Type 3 (mainnet launch + plan to migrate to Type 2) → Linea: Type 3 (mainnet launch + plan to migrate to Type 2) → Scroll : Type 3 (testnet launch + plan to switch to Type 1) → zkSync Era: Type 4 (mainnet launch)

All in all, L2 development and adoption is the key to the future of Ethereum + solving blockchain scalability issues. Each zkEVM has unique strengths and faces unique challenges, but they all play key roles in enabling an accessible web3 ecosystem.