Smart Contract Deployment to Optimism

Deploying Smart Contracts to Optimism

Optimism is an EVM-equivalent L2 based on OP Stack with Bedrock architecture. From a deployment perspective, contracts compile exactly as for Ethereum mainnet. Differences appear when working with L1↔L2 messaging, getting L1 block data and calculating gas fees.

Deployment Configuration

Add Optimism to Hardhat or Foundry configuration:

// hardhat.config.ts
networks: {
  optimism: {
    url: process.env.OPTIMISM_RPC ?? "https://mainnet.optimism.io",
    accounts: [process.env.DEPLOYER_PRIVATE_KEY!],
    chainId: 10,
  },
  "optimism-sepolia": {
    url: "https://sepolia.optimism.io",
    accounts: [process.env.DEPLOYER_PRIVATE_KEY!],
    chainId: 11155420,
  },
}

# Foundry
forge create src/MyContract.sol:MyContract \
  --rpc-url https://mainnet.optimism.io \
  --private-key $DEPLOYER_PRIVATE_KEY \
  --etherscan-api-key $OPTIMISM_ETHERSCAN_KEY \
  --verify

Gas on Optimism: Two Components

The main feature of Optimism (and all OP Stack chains) — gas fee consists of two parts:

L2 execution gas — like regular Ethereum gas, but significantly cheaper. Paid in ETH.

L1 data fee — cost of publishing transaction calldata to Ethereum mainnet (for data availability). After EIP-4844 (blobs), cost decreased 90%+.

The GasPriceOracle contract (address 0x420000000000000000000000000000000000000F) provides methods l1BaseFee(), baseFee(), gasPrice() for full cost calculation.

Contract Verification

Optimism has its own Etherscan (optimistic.etherscan.io) with separate API key:

npx hardhat verify --network optimism \
  --contract contracts/MyToken.sol:MyToken \
  DEPLOYED_ADDRESS \
  "Constructor Arg 1" "Constructor Arg 2"

For proxy contracts (OpenZeppelin TransparentUpgradeableProxy) verify implementation and proxy separately, then use Etherscan UI to link them.

OP Stack Specifics

Predeploys — system contracts deployed at fixed addresses. Important ones:

• 0x4200...0006 — L2CrossDomainMessenger (for L1↔L2 messages)
• 0x4200...0010 — L2StandardBridge (ERC-20 bridge)
• 0x4200...000F — GasPriceOracle

Sequencer and finality — transactions confirmed by sequencer quickly (2 seconds), but L1 finality takes ~7 days (challenge period). For most dApps this is not important, but account for it when working with L1 withdrawals.

Block time — 2 seconds. If contract uses block.timestamp for timeouts or TWAP calculations — this affects parameters.

Deployment via Foundry Script

// script/Deploy.s.sol
pragma solidity ^0.8.20;
import "forge-std/Script.sol";
import "../src/MyProtocol.sol";

contract DeployScript is Script {
    function run() external {
        uint256 deployerKey = vm.envUint("DEPLOYER_PRIVATE_KEY");
        vm.startBroadcast(deployerKey);
        
        MyProtocol protocol = new MyProtocol(
            0x4200000000000000000000000000000000000006 // L2CrossDomainMessenger
        );
        
        console.log("Deployed at:", address(protocol));
        vm.stopBroadcast();
    }
}

forge script script/Deploy.s.sol:DeployScript \
  --rpc-url https://mainnet.optimism.io \
  --broadcast \
  --verify \
  -vvvv

The --verify flag automatically verifies the contract after deployment. Foundry saves deployment addresses in the broadcast/ directory.

Testing on Optimism Sepolia

Before mainnet deployment test on Optimism Sepolia (chainId 11155420). Get test ETH through official faucet or Alchemy/Infura faucets. Optimism Sepolia mirrors mainnet configuration including system contracts.