EVM Compatibility on Layer 2 Networks

LABS

EVM Compatibility on Layer 2 Networks

Core Concepts of L2 EVM Compatibility

Understanding the technical foundations that allow Layer 2 networks to execute Ethereum smart contracts and transactions seamlessly.

EVM Equivalence

EVM Equivalence means the L2's execution environment is a perfect replica of Ethereum's, ensuring bytecode compatibility. This guarantees that any contract deployed on Ethereum L1 will execute identically on the L2 without modification. For developers, this eliminates the need for re-auditing or rewriting code, significantly reducing deployment risk and complexity for protocols like Uniswap or Aave when expanding to L2s.

Bytecode Compatibility

Bytecode Compatibility is the ability for the L2's virtual machine to interpret and execute the exact compiled EVM bytecode from Ethereum. This is a stricter standard than just supporting the Solidity language. It ensures that low-level opcodes and precompiled contracts behave identically, which is critical for complex DeFi applications that rely on specific gas costs and execution paths for security and economic logic.

Gas Economics & Fee Markets

L2s must maintain compatible gas economics to ensure predictable transaction costs. While fees are paid in the L2's native token or ETH, the underlying gas metering for opcodes mirrors Ethereum's. This allows existing tooling like gas estimators to function. However, L2s implement their own fee markets and compression techniques to reduce costs, which users encounter when bridging assets or interacting with dApps like OpenSea on Polygon.

RPC & Developer Tooling

A compatible JSON-RPC API allows developers to use existing Ethereum tools like MetaMask, Hardhat, and Ethers.js without changes. The L2 node must respond to standard calls (eth_getBalance, eth_sendTransaction) identically. This seamless integration is why users can add an Arbitrum network to their wallet with a familiar interface, and developers can deploy using the same scripts and testing frameworks they use for Ethereum mainnet.

State & Storage Layout

EVM-compatible state structure means the L2's account model, storage slots, and Merkle Patricia Trie layout are identical to Ethereum's. This is essential for trustless bridging and cross-chain messaging, as state proofs can be verified on L1. For users, this ensures that their token balances and NFT ownership represented by storage slots remain consistent and provable when moving assets between layers via bridges like the Arbitrum bridge.

Precompiled Contracts

Support for Ethereum's set of precompiled contracts is required for advanced cryptographic operations. These are hardcoded addresses (like 0x05 for MODEXP) that perform complex computations (e.g., elliptic curve pairings for zk-SNARKs) more efficiently. L2s must implement these precompiles identically for protocols like Aztec or applications using signature verification to function correctly, ensuring interoperability for privacy and scaling solutions.

Implementation Approaches by L2 Type

Understanding EVM Compatibility

EVM compatibility means a Layer 2 network can execute the same code and understand the same data structures as the Ethereum mainnet. This allows developers to deploy existing smart contracts with minimal changes and users to interact with familiar wallets like MetaMask.

Key Differences by L2 Type

Optimistic Rollups (Arbitrum, Optimism): These run a full EVM environment, offering near-perfect compatibility. Your contracts work as-is, but transactions have a 7-day challenge period before finalizing on Ethereum.
ZK-Rollups (zkSync Era, Polygon zkEVM): These use zero-knowledge proofs for security. They implement a zkEVM that translates EVM bytecode, sometimes requiring compiler adjustments or specific precompiles for complex operations.
Validiums (StarkEx): These offer high throughput but keep data off-chain. While they support Solidity via transpilers, their architecture is fundamentally different, which can limit compatibility with certain contract patterns.

Practical Implication

When bridging assets from Ethereum to an L2, you interact with a bridge contract. On Optimism, this feels identical to an Ethereum transaction. On a ZK-Rollup, you might need to use a custom bridge interface provided by the network.

Deploying Smart Contracts to an EVM-Compatible L2

Process overview for deploying a contract to a Layer 2 network like Arbitrum, Optimism, or Base.

Set Up Your Development Environment

Configure your project and wallet for the target L2 network.

Detailed Instructions

Initialize a new project using a framework like Hardhat or Foundry. Install the necessary dependencies, including the Ethers.js library and the specific L2's network package. Configure your hardhat.config.js to include the L2 network. You must add the network's RPC endpoint (e.g., https://arb1.arbitrum.io/rpc for Arbitrum One) and the corresponding chain ID (42161 for Arbitrum). Fund your deployment wallet with the L2's native gas token, which typically requires bridging assets from Ethereum Mainnet using the official bridge.

Sub-step 1: Run npm init -y and npm install --save-dev hardhat
Sub-step 2: Add network configuration for your target L2 in the Hardhat config file
Sub-step 3: Bridge ETH to your wallet address on the L2 via the canonical bridge

javascript
// Example Hardhat network config for Arbitrum
module.exports = {
  networks: {
    arbitrumOne: {
      url: "https://arb1.arbitrum.io/rpc",
      accounts: [process.env.PRIVATE_KEY]
    }
  }
};

Tip: Use a .env file to securely manage your private key and RPC URLs.

Adapt Contract Code for L2 Specifics

Review and modify smart contracts for L2 gas optimization and compatibility.

Detailed Instructions

While EVM compatibility ensures most Solidity code works, L2s have different gas economics and potential opcode support. Audit your contracts for operations expensive on L2, like excessive storage writes or use of SELFDESTRUCT. Consider using L2-native precompiles for features like cryptographic verification if available. If your contract interacts with Ethereum Mainnet, you must implement a cross-chain messaging pattern, such as Arbitrum's L1 to L2 retryable tickets or Optimism's cross-domain messengers. Ensure address aliasing is handled if your contract expects messages from an L1 contract.

Sub-step 1: Profile gas costs of key functions using a local L2 testnet fork
Sub-step 2: Replace any Mainnet-specific assumptions (e.g., block times, gas limits)
Sub-step 3: Integrate the L2's official bridge or messaging contract interface

solidity
// Example: Importing Optimism's cross-domain messenger interface
import { ICrossDomainMessenger } from "@eth-optimism/contracts/L1/messaging/ICrossDomainMessenger.sol";

contract MyL2Contract {
    ICrossDomainMessenger public immutable MESSENGER = ICrossDomainMessenger(0x4200000000000000000000000000000000000007);
}

Tip: Use tx.gasprice in your contracts cautiously, as L2 gas prices are more volatile.

Test Extensively on L2 Testnets

Deploy and validate contract functionality on a dedicated L2 test network.

Detailed Instructions

Deploy your contract to the L2's testnet (e.g., Arbitrum Sepolia, Optimism Goerli). Use a forked testing environment to simulate complex interactions with Mainnet contracts. Write comprehensive tests that verify both core logic and L2-specific behaviors, such as cross-chain message finality and fee payment with the L2's native token. Test edge cases related to sequencer downtime by submitting transactions directly to the L1 inbox contract. Validate that all event emissions and storage changes occur correctly. Use a block explorer for the testnet to manually verify deployments and transactions.

Sub-step 1: Run npx hardhat test --network arbitrumSepolia to execute your test suite
Sub-step 2: Simulate a cross-chain withdrawal and challenge period using a local fork
Sub-step 3: Verify contract source code on the L2 testnet block explorer

bash
# Example command to run tests on a forked Arbitrum mainnet
npx hardhat test --network hardhat
# Config for forking in hardhat.config.js:
# hardhat: { forking: { url: "https://arb1.arbitrum.io/rpc" } }

Tip: Account for the longer block time on some L2s (e.g., 2 seconds) in your timing-dependent tests.

Deploy to L2 Mainnet and Verify

Execute the mainnet deployment and publish source code verification.

Detailed Instructions

Execute the deployment script targeting the L2 mainnet network. Monitor the deployment transaction closely on the block explorer, as L2 transactions have a different confirmation flow; they are first processed by the sequencer before being proven on Ethereum. After deployment, immediately verify the contract source code using the block explorer's verification tool or a Hardhat plugin. This is critical for user trust and interaction. Set up initial contract parameters, transfer ownership to a multisig wallet or DAO, and revoke any temporary admin privileges. Finally, conduct a final suite of live mainnet tests on a small scale.

Sub-step 1: Run npx hardhat run scripts/deploy.js --network arbitrumOne
Sub-step 2: Use npx hardhat verify --network arbitrumOne <CONTRACT_ADDRESS> <CONSTRUCTOR_ARGS>
Sub-step 3: Call a initialization function to set up roles and link required addresses

javascript
// Example deployment script snippet for Hardhat
async function main() {
  const MyContract = await ethers.getContractFactory("MyContract");
  const myContract = await MyContract.deploy("ConstructorArgument");
  await myContract.deployed();
  console.log("Contract deployed to:", myContract.address);
}

Tip: Budget for deployment costs, which include L2 execution gas and a portion of the L1 data availability fee.

Monitor and Manage Post-Deployment

Implement ongoing monitoring, upgradeability, and cross-chain management.

Detailed Instructions

Establish monitoring for contract events, balance changes, and gas usage spikes using a service like Tenderly or The Graph. If your contract uses a proxy upgrade pattern, ensure the admin functions are securely managed. For contracts that hold funds, implement a withdrawal process that accounts for the L2's withdrawal delay (e.g., 7 days for Optimistic Rollups). Monitor the L1 bridge contract for any security announcements or upgrades that may affect your application. Keep track of L2 network upgrades and test your contracts on a pre-release testnet before the upgrade goes live.

Sub-step 1: Set up alerts for failed transactions or unusual event patterns from your contract
Sub-step 2: Test and execute a contract upgrade via your proxy admin on the L2 testnet first
Sub-step 3: Initiate a withdrawal of funds to L1 and track the challenge period

solidity
// Example: Function to initiate a withdrawal on an Optimistic Rollup
function withdrawToL1(address l1Recipient, uint256 amount) external {
    // Burn the L2 tokens
    _burn(msg.sender, amount);
    // Send cross-domain message to finalize withdrawal on L1
    MESSENGER.sendMessage(
        l1BridgeAddress,
        abi.encodeWithSignature("finalizeWithdrawal(address,uint256)", l1Recipient, amount),
        1000000 // Gas limit for L1 execution
    );
}

Tip: Consider using a relayer service to pay gas fees for users on L2 to improve UX.

EVM Compatibility Comparison Across Major L2s

A technical comparison of EVM implementation, performance, and operational characteristics across leading Layer 2 networks.

Feature / Metric	Arbitrum One	Optimism	zkSync Era	Base
EVM Opcode Compatibility	Full (Arbitrum Nitro)	Full (EVM-Equivalent)	~99% (zkEVM)	Full (OP Stack Bedrock)
Average Time to Finality	~5 minutes	~1 minute	~10 minutes	~1 minute
Avg. Transaction Fee (Simple Swap)	$0.10 - $0.30	$0.05 - $0.15	$0.01 - $0.05	$0.01 - $0.10
Max Transaction Gas Limit	~30M gas	~30M gas	~13M gas	~30M gas
Contract Size Limit	24KB	24KB	~48KB (post-EIP-170)	24KB
Precompile Support	All Ethereum precompiles	All Ethereum precompiles	Limited (e.g., no MODEXP)	All Ethereum precompiles
Native Account Abstraction	No (via third-party)	Yes (via EIP-4337 Bundler)	Native (AA by default)	Yes (via EIP-4337 Bundler)
Data Availability Layer	Ethereum (calldata)	Ethereum (calldata)	Ethereum (calldata + state diffs)	Ethereum (calldata)

Technical Challenges and Considerations

Implementing EVM compatibility involves navigating a series of technical trade-offs and architectural decisions that directly impact security, performance, and developer experience.

State Management

State synchronization between L1 and L2 is a core challenge.

Optimistic rollups post state roots with a delay for fraud proofs, creating a withdrawal period.
ZK-rollups generate validity proofs for each batch, enabling faster finality but with higher computational cost.
This dictates user experience for fund withdrawals and contract state finality.

Gas Cost & Opcode Parity

Achieving gas equivalence is difficult as L2s have different cost structures.

Some precompiles (e.g., BLAKE2f) or opcodes may be disabled or repriced.
Storage operations are often optimized and cheaper on L2.
Developers must audit gas usage, as contracts optimized for L1 may behave unexpectedly on specific L2s.

Sequencer Centralization

Most L2s use a single sequencer to order transactions for efficiency, creating a trust assumption.

Users rely on the sequencer for transaction inclusion and latency.
Censorship resistance is reduced compared to L1.
The ecosystem is evolving towards decentralized sequencer sets and based sequencing to mitigate this.

Proving System Complexity

ZK-rollups require integrating a zero-knowledge proof system (e.g., SNARKs, STARKs) with the EVM.

This involves creating a circuit for EVM execution, which is computationally intensive.
Prover hardware requirements are high, affecting who can participate.
Proof generation time can become a bottleneck during network congestion.

Contract Upgradeability

L2s often implement custom upgrade mechanisms for their core contracts (e.g., verifiers, bridges).

This introduces governance risk distinct from the underlying application.
A malicious upgrade could compromise bridge security.
Users must monitor the security model of both the L2 protocol and its bridge.

Data Availability

Ensuring data availability for transaction data is critical for security.

Validium solutions post proofs to L1 but keep data off-chain, relying on a committee.
This trades off scalability for reduced trustlessness.
Applications holding significant value may require the full data-on-L1 guarantee of a rollup.

SECTION-FAQ

Frequently Asked Questions on L2 EVM Compatibility

Developer Resources and Documentation

Optimism Developer Documentation

Details Optimism's EVM equivalence, L2 execution model, opcode differences, and deployment considerations for Solidity contracts.

Visit resource

Arbitrum Developer Docs

Covers Arbitrum Nitro architecture, EVM compatibility guarantees, precompiles, gas mechanics, and L1 to L2 contract interactions.

Visit resource

zkSync Era Documentation

Explains zkEVM design tradeoffs, Solidity and Vyper support, system contracts, and differences from Ethereum mainnet semantics.

Visit resource

Polygon zkEVM Docs

Technical reference for Polygon zkEVM including bytecode-level compatibility, proving system constraints, and deployment workflows.

Visit resource

Scroll Documentation

Describes Scroll's bytecode-level EVM equivalence, supported tooling, and limitations affecting contract portability from Ethereum.

Visit resource

Ready to Start Building?

Let's bring your Web3 vision to life.

From concept to deployment, ChainScore helps you architect, build, and scale secure blockchain solutions.

Start Your Project View Our Work