Building and auditing on Base, an OP Stack rollup on Ethereum: EVM equivalence, cross-domain messaging, sequencer assumptions and how to prepare.
Base is an Ethereum layer 2 network built on the OP Stack, the same open-source rollup framework as Optimism. It executes transactions off Ethereum, posts their data back to it and inherits the optimistic rollup security model. For a project, it offers Ethereum-style development at lower transaction cost, with the rollup assumptions that come with it.
Building on Base
Base is EVM-equivalent: Solidity and Vyper contracts compile and behave as on Ethereum, and the usual development tools work unchanged. A single sequencer orders transactions, bridge and messenger contracts connect Base to Ethereum, and withdrawals to Ethereum finalize after a challenge period. Many projects deploy the same codebase on Base and on other EVM networks, which makes consistent configuration across chains a recurring concern.
Languages: Solidity, Vyper
Frameworks: Foundry, Hardhat
Fees combine L2 execution gas with the cost of posting data to Ethereum
What auditors look at
Sequencer assumptions: impact of downtime or delayed transactions on liquidations, auctions and time-sensitive logic
Cross-domain messaging with Ethereum: authentication of the messenger and original sender, failed or replayed messages
Bridged tokens: whether the contract accepts the canonical bridged version, a wrapped variant, or both
Multichain deployments: addresses, roles and parameters that must be set correctly on each network
Classic EVM risks such as reentrancy, oracle manipulation and access control, which remain the main sources of findings
Before requesting quotes
List every network where the code will run and the per-chain differences in configuration
Document the oracles, bridged assets and external protocols your contracts rely on
Describe how the system should behave if the sequencer stops or withdrawals are delayed
Provide a test suite that runs against a fork of the network where external integrations matter