A Ground-Up Guide to zkEVM, EVM Compatibility, and Rollups

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The future of Ethereum scalability hinges on rollups — particularly zero-knowledge rollups (zk-rollups). Long considered the endgame for Ethereum’s Layer 2 evolution, zk-rollups promise massive throughput while preserving Ethereum’s unmatched security. But despite their growing prominence, confusion remains around key concepts: What exactly is a zkEVM? What does “EVM compatible” really mean? And how do different rollup designs impact developers and users?

This guide breaks down the fundamentals of zk-rollups, EVM compatibility, and the trade-offs shaping the next generation of scalable blockchains.

Understanding ZK-Rollups

At their core, zk-rollups leverage cryptographic proofs — specifically zero-knowledge proofs like STARKs or SNARKs — to process transactions off-chain while securely anchoring the results to Ethereum Layer 1 (L1).

Here’s how they work:

  1. Users deposit assets into a smart contract on Ethereum.
  2. Transactions are sent to an off-chain sequencer, which batches them and generates a validity proof (e.g., SNARK/STARK) along with a state update.
  3. The proof and updated state are submitted back to L1, where the contract verifies the proof and applies the changes.
  4. Users can withdraw their funds at any time using data published on L1, ensuring full self-custody.

👉 Discover how leading platforms are implementing zero-knowledge technology today.

Because verifying a proof is far cheaper than re-executing all transactions on-chain, zk-rollups drastically reduce gas costs and increase scalability. For deeper insight, Vitalik Buterin’s Incomplete Guide to Rollups offers an excellent technical foundation.

Application-Specific vs. General-Purpose Rollups

Most live zk-rollups today are application-specific — optimized for narrow use cases like NFT minting or perpetual trading. Examples include:

These rollups excel by limiting supported operations, enabling superior performance, lower fees, and better user experiences. For instance, Immutable subsidizes gas fees for NFT transfers thanks to predictable transaction patterns.

However, application-specific rollups lack flexibility. They don’t allow arbitrary smart contract deployment or composability — the ability for apps to interact seamlessly, as seen in DeFi protocols using Uniswap as a price oracle.

To support open-ended development, we need general-purpose zk-rollups — systems capable of running any EVM-compatible code. This shift introduces new challenges in performance and complexity but unlocks full programmability.

Projects like StarkNet, zkSync, Polygon zkEVM, and Scroll are pioneering this space, each adopting distinct approaches to balance compatibility, speed, and developer experience.

What Is the EVM?

The Ethereum Virtual Machine (EVM) is the runtime environment for executing smart contracts on Ethereum. Defined in the Yellow Paper and updated via EIPs (Ethereum Improvement Proposals), it includes:

Every Ethereum transaction runs within this sandboxed environment. The EVM’s design prioritizes security and decentralization over raw performance — a trade-off that has proven resilient since 2015.

Due to Ethereum’s dominance, many blockchains adopted the EVM directly. Chains like Polygon and BNB Chain are EVM forks, ensuring broad tooling support. However, they often lag behind Ethereum’s latest upgrades (e.g., EIP-1559), creating subtle incompatibilities.

Beyond the VM: What "EVM Compatible" Really Means

While “EVM compatible” suggests runtime equivalence, it often refers to broader ecosystem alignment:

True compatibility means more than just supporting EVM bytecode — it’s about enabling seamless migration of tools, dApps, and developer workflows.

Chains that deviate — even slightly — risk breaking tooling or requiring custom configurations. Conversely, non-EVM chains like Solana must build parallel ecosystems from scratch, though they gain freedom to innovate beyond Ethereum’s constraints.

👉 Explore how next-gen rollups are redefining blockchain compatibility.

The Rise of zkEVMs

A zkEVM is a general-purpose zk-rollup that executes EVM-compatible code and produces validity proofs. The goal? Maximize developer adoption by minimizing friction when moving from L1 Ethereum.

But proving EVM execution is hard. Zero-knowledge proofs require computations to be expressed as algebraic circuits — mathematical representations that can be efficiently verified. Translating complex EVM operations (especially cryptographic ones) into circuits is a major engineering challenge.

There are three primary strategies:

1. Prove the EVM Execution Trace (Scroll)

Scroll aims to directly prove EVM execution by compiling every opcode into a zk-friendly circuit. This approach ensures maximum compatibility with Ethereum — in theory, any Solidity contract runs unchanged.

However, building circuits for all ~140 opcodes is extremely complex. Scroll collaborates with the Ethereum Foundation’s Privacy & Scaling Explorations group to achieve this ambitious goal.

While highly compatible, this method sacrifices performance due to circuit overhead. Still, it offers long-term maintainability as Ethereum evolves.

2. Custom VM + Opcode Mapping (Polygon zkEVM)

Polygon zkEVM uses a custom runtime called zkExecutor, which translates EVM opcodes into optimized zkASM instructions. This intermediate layer allows faster proving at the cost of slight deviations from native EVM behavior.

Most Solidity code works out of the box, but low-level assembly or complex contracts may require adjustments. Polygon claims full tooling compatibility via JSON-RPC adherence — though real-world integration depends on how tightly tools assume pure EVM equivalence.

This design trades some compatibility for significantly better prover performance.

3. Custom VM + Transpiler (StarkNet & zkSync)

StarkNet and zkSync take a different path: build a purpose-built VM optimized for ZK proofs.

These systems prioritize performance and innovation over direct compatibility. For example, zkSync supports account abstraction natively — a feature not yet available on Ethereum.

While powerful, this approach risks fragmentation. Contracts written in Cairo and Solidity may struggle to interoperate. Additionally, ecosystem tools must add explicit support for these chains.

Vitalik’s zkEVM Types: A Framework for Comparison

Vitalik Buterin proposed a classification system for zkEVMs based on compatibility levels:

Scroll leans toward Type 1/2, Polygon targets Type 2/3, while StarkNet and zkSync align with Type 4.

Crucially, no single approach is “best.” Each makes trade-offs between performance, upgradeability, and developer experience.

Current State of General-Purpose Rollups

As of now, no general-purpose zkEVM operates at full production scale. StarkNet leads in deployment but faces UX hurdles due to limited tooling. Others are in testnet or late development stages.

Expect at least a year of iteration between testnet launch and stable mainnet performance — as seen with StarkNet’s evolution.

For projects needing scale today, application-specific rollups remain the strongest choice, offering proven reliability for targeted use cases like gaming or DeFi.

Even once general rollups mature, specialized solutions will likely dominate niche domains where customization and efficiency matter most.

Key Factors Beyond Compatibility

When choosing a rollup, consider more than just EVM alignment:

These factors directly impact decentralization, user trust, and long-term viability.

👉 See how top rollups are addressing scalability without compromising security.

FAQs

Q: Can I deploy my existing Solidity contracts on zkEVMs?
A: Most can be deployed with little or no changes — especially on Type 1–3 zkEVMs like Scroll or Polygon. Type 4 systems may require minor adjustments or transpilation.

Q: Are zkEVMs as secure as Ethereum?
A: Security relies on correct implementation and data availability. With on-chain data publishing (like Rollup mode), they inherit Ethereum’s security guarantees.

Q: Do zkEVMs support all Ethereum tools?
A: Not always. While JSON-RPC is often supported, tools relying on deep EVM behavior (e.g., debuggers) may not work perfectly across all zkEVM types.

Q: What’s the difference between optimistic and zk-rollups?
A: Optimistic rollups assume validity by default and use fraud proofs; zk-rollups use validity proofs. ZK-proofs offer faster finality and stronger security assumptions.

Q: Will gas fees disappear on zkEVMs?
A: Fees are drastically reduced due to batched proofs, but not eliminated. Users still pay for computation and data publication.

Q: Which zkEVM should I build on today?
A: For production apps, consider application-specific rollups first. For experimental or future-facing projects, evaluate testnet maturity and roadmap clarity of general-purpose options.

Final Thoughts

The race to build scalable Ethereum is well underway. While debates over “true” EVM compatibility dominate headlines, the reality is nuanced: every solution balances trade-offs between performance, compatibility, and innovation.

Developers should look beyond marketing claims and ask concrete questions:

As merge-complete Ethereum evolves, both specialized and general-purpose rollups will play vital roles. The ecosystem isn’t moving toward one winner — but toward a diverse landscape where choice empowers innovation.

The future of scalable smart contracts isn’t just coming — it’s being built now.