A ZK-EVM is a core component of zero-knowledge rollup (zk-rollup) scaling solutions. It is a specialized virtual machine that is fully compatible with the Ethereum Virtual Machine (EVM) at either the bytecode or opcode level, allowing developers to deploy existing smart contracts and tools with minimal changes. Its primary function is to process transactions off-chain and produce a zero-knowledge proof (typically a ZK-SNARK or ZK-STARK), a small cryptographic certificate that verifies all computations were performed correctly according to Ethereum's rules, without revealing the underlying transaction data.
LABS
Glossary
ZK-EVM
A Zero-Knowledge Ethereum Virtual Machine (ZK-EVM) is a virtual machine that executes Ethereum smart contracts and generates cryptographic validity proofs of that execution, enabling trust-minimized Layer 2 scaling.
Chainscore © 2026
definition
BLOCKCHAIN SCALING TECHNOLOGY
What is ZK-EVM?
A ZK-EVM (Zero-Knowledge Ethereum Virtual Machine) is a virtual machine that executes Ethereum smart contracts and generates cryptographic proofs of the correctness of that execution, enabling scalable Layer 2 networks.
The generated validity proof is then posted to the Ethereum mainnet, where it is verified by a smart contract. This allows the Layer 1 to inherit the security guarantees of the off-chain execution while only storing a tiny proof and minimal data on-chain. This architecture provides massive scalability improvements by compressing thousands of transactions into a single proof, drastically reducing gas costs and increasing transaction throughput. Key implementations include zkSync Era, Polygon zkEVM, Scroll, and Starknet (with its Cairo VM).
ZK-EVMs are categorized by their level of equivalence to the mainnet EVM. A Type 1 ZK-EVM aims for full Ethereum equivalence, proving even consensus-layer details, while a Type 4 ZK-EVM compiles high-level Solidity code to a different, proof-optimized instruction set. The choice involves a trade-off between compatibility, proof generation speed (prover time), and ease of development. This technology is fundamental to achieving the Ethereum scaling roadmap's vision of a secure, high-throughput network via Layer 2 rollups.
etymology
TERM ROOTS
Etymology & Origin
The term ZK-EVM is a compound acronym that reveals its core technological ambition: to combine the privacy and scalability of zero-knowledge proofs with the universal compatibility of the Ethereum Virtual Machine.
The term ZK-EVM is a portmanteau of ZK (Zero-Knowledge) and EVM (Ethereum Virtual Machine). Its etymology directly maps to its function: a virtual machine that executes smart contracts in a manner compatible with Ethereum's EVM, but which produces a zero-knowledge proof (specifically a ZK-SNARK or ZK-STARK) to verify the correctness of that execution. This proof, known as a validity proof, allows any observer to be convinced of the state transition's integrity without re-executing the transactions, enabling secure scaling through ZK-rollups.
The conceptual origin of ZK-EVMs lies in the convergence of two major blockchain research trajectories. The first is the long-standing pursuit of scalability solutions, particularly rollups, which process transactions off-chain. The second is the advancement in cryptographic proving systems, which made generating proofs for complex computations like EVM execution pragmatically feasible. Early implementations, such as those by zkSync and Scroll, emerged around 2021-2022, striving to create a bytecode-compatible environment where existing Ethereum smart contracts could run with minimal modification.
The development of ZK-EVMs introduced a key taxonomy based on their level of compatibility with Ethereum, often described as a spectrum. A Type 1 ZK-EVM (fully equivalent) aims for perfect compatibility at the expense of proof generation speed. A Type 2 ZK-EVM (EVM-equivalent) matches Ethereum's state and bytecode exactly for developers, while a Type 3 (language-compatible) and Type 4 (high-level language compatible) make trade-offs for performance. This classification, popularized by Ethereum co-founder Vitalik Buterin, helps delineate the trade-off between developer experience, proof efficiency, and decentralization.
The ultimate origin story of the ZK-EVM is part of Ethereum's broader rollup-centric roadmap. As Ethereum transitioned to Proof-of-Stake with The Merge, scaling emphasis shifted to Layer 2 solutions. ZK-rollups, powered by ZK-EVMs, are seen as a critical endgame technology for achieving scalability without compromising security. Their evolution is marked by milestones like the introduction of custom precompiles, specialized proof circuits, and ongoing work to make them as seamless and accessible as the native Ethereum chain for developers and users alike.
key-features
ZK-EVM
Key Features
A Zero-Knowledge Ethereum Virtual Machine (ZK-EVM) is a virtual machine that generates cryptographic proofs of correct EVM execution. It enables Layer 2 scaling by bundling transactions and submitting a succinct proof to Ethereum, inheriting its security.
01
EVM Equivalence
The highest standard for compatibility, where a ZK-EVM executes bytecode identically to the Ethereum mainnet. This ensures:
- No code modifications required for existing smart contracts.
- Full compatibility with all Ethereum developer tooling (e.g., MetaMask, Hardhat).
- Seamless portability of dApps from L1 to L2.
02
ZK Proof Generation
The core cryptographic engine that produces a validity proof (e.g., a SNARK or STARK). This process:
- Verifies that all transactions in a batch were executed correctly.
- Compresses the computation into a small proof (a few KB).
- Enables trustless bridging, as the Ethereum L1 only needs to verify the proof, not re-execute the transactions.
03
Fast Finality
Transactions achieve cryptographic finality as soon as the proof is verified on Ethereum, typically in minutes. This is distinct from the probabilistic finality of Optimistic Rollups, which have a 7-day challenge period. Users and bridges do not need to wait for a dispute window.
04
Data Availability
Critical for ensuring state can be reconstructed. Most ZK-Rollups post calldata (transaction data) to Ethereum L1. Key models include:
- ZK-Rollup (on-chain data): Full data posted, maximizing security.
- Validium: Data kept off-chain with a Data Availability Committee (DAC), offering higher throughput but introducing a trust assumption.
05
Prover Architecture
The specialized hardware/software system that generates proofs. Key components are:
- State Manager: Tracks the rollup's world state (accounts, storage).
- Witness Generator: Creates the computational "witness" for the proof.
- Prover: Runs the proving algorithm (e.g., Plonk, STARK). Proving is computationally intensive, often requiring optimized hardware.
06
Cross-Chain Messaging
Enables secure communication between the ZK-EVM and Ethereum L1 via bridges. This allows for:
- Trustless deposits: Users send assets from L1 to L2.
- Trustless withdrawals: Users prove ownership of L2 assets to withdraw to L1, secured by the validity proof.
- Contract calls: L1 contracts can securely read state from the L2.
how-it-works
TECHNICAL DEEP DIVE
How a ZK-EVM Works
A Zero-Knowledge Ethereum Virtual Machine (ZK-EVM) is a specialized virtual machine that executes Ethereum transactions and smart contracts while generating cryptographic proofs of their correctness, enabling trustless scaling and interoperability.
A ZK-EVM is a core component of ZK-rollup scaling solutions. It functions as a deterministic state machine that processes transactions identically to the standard Ethereum Virtual Machine (EVM), ensuring full bytecode-level compatibility. However, its primary output is not just a new state root, but a zero-knowledge proof (typically a ZK-SNARK or ZK-STARK). This cryptographic proof, known as a validity proof, attests that the state transition was executed correctly according to Ethereum's rules, without revealing the underlying transaction data.
The operational workflow involves several distinct phases. First, a sequencer or prover node executes a batch of transactions within the ZK-EVM, generating an execution trace. This trace is then fed into a proof system (e.g., a circuit built with libraries like Halo2 or Plonky2), which generates a succinct proof. This proof is posted to the Ethereum mainnet, where a verifier smart contract checks its validity. If the proof is valid, the new state root is accepted, finalizing the batch. This process decouples expensive execution and proof generation from the inexpensive on-chain verification.
Architecturally, ZK-EVMs are categorized by their level of equivalence to the standard EVM. A Type 1 (fully equivalent) ZK-EVM aims for perfect compatibility but is complex to build. A Type 2 (EVM-equivalent) ZK-EVM is compatible at the bytecode level but may have minor gas cost differences. A Type 3 (almost EVM-equivalent) ZK-EVM may sacrifice some compatibility for easier proof generation, while a Type 4 compiles high-level Solidity code directly to a custom ZK-friendly language. Each type represents a different trade-off between compatibility, performance, and development effort.
The proving process is computationally intensive, often requiring specialized hardware or cloud services. Key technical challenges include efficiently representing EVM opcodes (like SSTORE, CALL, and SHA3) within arithmetic circuits and managing the large state witnesses required for proofs. Innovations in proof recursion and aggregation, such as proof of proofs, are critical for reducing the final verification cost on Ethereum L1 and enabling sustainable, low-fee transactions for end-users.
In practice, ZK-EVMs enable a new paradigm for blockchain scaling and interoperability. Projects like zkSync Era, Polygon zkEVM, Scroll, and Linea implement different ZK-EVM architectures to provide developers with a seamless experience. By generating cryptographic guarantees of correctness, ZK-EVMs provide the security of Ethereum L1 with the throughput of a separate execution layer, forming the foundation for a scalable, unified multi-chain ecosystem.
ZK-EVM TYPES
Spectrum of EVM Compatibility
A comparison of different approaches to building a Zero-Knowledge Ethereum Virtual Machine, categorized by their level of equivalence to the standard EVM.
| Architectural Feature | Type 1 (Fully Equivalent) | Type 2 (EVM-Equivalent) | Type 3 (EVM-Compatible) | Type 4 (Language-Compatible) |
|---|---|---|---|---|
Goal | Full Ethereum L1 equivalence | EVM equivalence at L2 | Major EVM compatibility | Ethereum toolchain compatibility |
Data Structures | Identical to Ethereum (Patricia Merkle Trie) | Identical to Ethereum | Modified (e.g., different state tree) | Custom for ZK-friendliness |
Precompiles | All Ethereum precompiles supported | Most precompiles supported; some may be modified | Key precompiles supported; some omitted | Only essential precompiles; often re-implemented |
ZK-Prover Overhead | Highest (proves all EVM opcodes directly) | High | Medium (optimizes problematic opcodes) | Lowest (uses custom ZK-friendly VM) |
Developer Experience | Identical to Ethereum L1 | Virtually identical | Most dApps work; some re-audits needed | Requires recompilation or source code adaptation |
Proving Time (Relative) | Slowest | Slow | Faster | Fastest |
Example | zkEVM (Privacy-focused L1) | Polygon zkEVM, Scroll, zkSync Era | Early versions of zkSync, some optimistic rollups | zkSync Lite, StarkNet (Cairo VM) |
examples-ecosystem
ZK-EVM
Examples & Ecosystem
The ZK-EVM landscape is defined by different approaches to compatibility and performance. This section breaks down the major types and leading implementations.
01
Type 1: Fully Equivalent
A Type 1 ZK-EVM aims for perfect, byte-for-byte equivalence with the Ethereum mainnet. It does not modify any core Ethereum structures (consensus, state tree, precompiles), making its proofs verifiable directly on Ethereum L1. This provides the highest security and compatibility but is the most computationally intensive to prove.
- Example: Taiko, which is building a Type 1 ZK-Rollup.
- Trade-off: Maximum decentralization and security, but slower proof generation.
02
Type 2: EVM-Equivalent
A Type 2 ZK-EVM is functionally equivalent to Ethereum at the EVM level but may have minor state structure differences (e.g., a modified Merkle tree). It aims for full compatibility with existing developer tooling, smart contracts, and dApps without modification.
- Example: The zkSync Era ZK-Rollup.
- Key Benefit: Developers can deploy existing Solidity/Vyper contracts with minimal changes, preserving the Ethereum experience while improving scalability.
03
Type 3 & 4: High Performance
These types prioritize proof generation speed and cost over strict equivalence.
- Type 3: Almost EVM-Equivalent: Supports most popular dApps but may lack support for some precompiles or opcodes, requiring minor contract adjustments. Scroll began as Type 3 and is evolving toward Type 2.
- Type 4: High-Level Language Compatible: Operates at the language level (e.g., Solidity, Vyper), compiling source code directly into a custom ZK-friendly VM. This enables very fast proofs but breaks bytecode-level compatibility.
- Example (Type 4): Polygon zkEVM uses a custom zkASM to execute translated bytecode.
security-considerations
ZK-EVM
Security Model & Considerations
A Zero-Knowledge Ethereum Virtual Machine (ZK-EVM) is a core component enabling ZK-Rollups by generating cryptographic proofs of correct EVM execution. Its security model is defined by the integrity of its proof system and the trust assumptions of its data availability layer.
01
Soundness & Validity Proofs
The primary security guarantee of a ZK-EVM is soundness: if the proof verifies, the underlying execution is correct with cryptographic certainty (e.g., 2^128 security). This is enforced by a validity proof (ZK-SNARK or ZK-STARK) that attests to the integrity of state transitions, making invalid state transitions computationally impossible to prove. The system's security reduces to the hardness of the underlying cryptographic assumptions (e.g., elliptic curve discrete log).
02
Data Availability & Censorship Resistance
A ZK-Rollup's security depends on the data availability of its transaction batches. Users must be able to reconstruct the rollup state to exit, even if the sequencer is malicious. Solutions include:
- Ethereum calldata: Highest security, inheriting from L1.
- EigenDA / Celestia: External data availability committees with crypto-economic security.
- Validiums: Data kept off-chain, introducing a trust assumption that the committee will not withhold data. The choice directly impacts liveness and censorship resistance.
03
Prover Centralization & Trusted Setup
Two key operational risks exist:
- Prover Centralization: If proof generation is controlled by a single entity, they could censor transactions or stop producing proofs, halting the chain. Decentralized prover networks mitigate this.
- Trusted Setup: Some ZK-SNARK constructions require a trusted setup ceremony to generate public parameters. A compromised ceremony could allow forging proofs. Transparent systems like ZK-STARKs or perpetual powers-of-tau ceremonies aim to eliminate or minimize this trust.
04
EVM Equivalence & Implementation Bugs
A ZK-EVM's security is only as good as its correctness. Bugs in the circuit implementation (the code that defines provable constraints) are a critical risk. A bug could allow a malicious prover to generate a valid proof for an invalid state transition. Levels of equivalence:
- Bytecode-level: Proves EVM bytecode execution; must perfectly emulate all EVM edge cases.
- Language-level: Proves higher-level language (e.g., Solidity) execution, introducing a compiler trust assumption. Formal verification and extensive audit cycles are essential.
05
Upgradeability & Governance Risk
Most ZK-EVM implementations have upgradeable contracts for their verifier and bridge. This introduces governance risk: a malicious or coerced upgrade could introduce a bug or a backdoor. Security models vary:
- Multi-sig / Council: Fast upgrades, higher trust assumption.
- Timelock + Governance Token: Slower, more decentralized, but subject to token-holder capture.
- Immutable: Highest security but no ability to fix critical bugs. The upgrade mechanism is a central point of failure.
06
Sequencer & Bridge Security
The sequencer orders transactions and submits batches + proofs. A malicious sequencer can:
- Censor user transactions.
- Steal MEV through transaction reordering.
- Cause liveness failures. The bridge contract on L1 holds all locked funds. Its security is paramount. Risks include:
- Verifier contract bugs.
- Proof verification DoS via gas limit issues.
- Fraudulent proof acceptance due to the above risks. Economic slashing and decentralized sequencing are active areas of development to mitigate these.
ZK-EVM
Common Misconceptions
Zero-Knowledge Ethereum Virtual Machines are often misunderstood. This section clarifies key technical distinctions and addresses frequent points of confusion in the ecosystem.
No, a ZK-EVM is a core proving technology, while a Layer 2 is a blockchain scaling solution that may use it. A ZK-EVM is the engine that generates cryptographic proofs (ZK-SNARKs or ZK-STARKs) of correct EVM execution. A ZK-Rollup is a specific type of Layer 2 that bundles transactions and uses a ZK-EVM to create a validity proof for the entire batch, which is then posted to Ethereum Layer 1. Other scaling approaches, like Optimistic Rollups, do not use ZK-EVMs. Therefore, while all ZK-Rollups require a ZK-EVM, not all ZK-EVMs are deployed as independent Layer 2 chains; they can also be used for other applications like privacy or interoperability.
TECHNICAL DEEP DIVE
ZK-EVM
Zero-Knowledge Ethereum Virtual Machines (ZK-EVMs) are specialized proving systems that generate cryptographic proofs of correct EVM execution, enabling trustless scaling and interoperability.
A ZK-EVM is a virtual machine compatible with the Ethereum Virtual Machine (EVM) that produces zero-knowledge proofs (ZKPs) to cryptographically verify the correctness of transaction execution. It works by executing transactions in a prover node, generating a computational trace. This trace is then used to create a succinct proof (like a zk-SNARK or zk-STARK) that attests to the validity of the state transition. A separate verifier node can check this proof almost instantly, without re-executing the transactions, enabling high-throughput Layer 2 rollups like zkSync, Polygon zkEVM, and Scroll.
Core Process:
- Execution: Transactions are processed in a ZK-EVM environment.
- Proof Generation: A prover creates a cryptographic proof of the execution's correctness.
- Verification & Settlement: The proof is posted to Ethereum L1, where a verifier contract checks it and finalizes the state update.
ZK-EVM
Frequently Asked Questions
Zero-Knowledge Ethereum Virtual Machines (ZK-EVMs) are a critical innovation for scaling and privacy. This FAQ addresses the core technical concepts, implementation types, and practical implications for developers and users.
A ZK-EVM (Zero-Knowledge Ethereum Virtual Machine) is a virtual machine that executes Ethereum smart contracts and transactions, then generates a cryptographic proof (a zk-SNARK or zk-STARK) attesting to the correctness of that execution. It works by processing transactions in a specialized environment, generating a witness (the execution trace), and using a prover algorithm to create a succinct proof. A verifier can then check this proof in milliseconds, confirming the entire batch of transactions is valid without re-executing them. This enables Layer 2 scaling (like zkRollups) by posting only the tiny proof to Ethereum mainnet, drastically reducing cost and increasing throughput while inheriting Ethereum's security.
ENQUIRY
Get In Touch
today.
Our experts will offer a free quote and a 30min call to discuss your project.
NDA Protected
Confidentiality24h Response
Time to ValueDirectly to Engineering Team
No Sales Fluff10+
Protocols Shipped
$20M+
TVL Overall