Base Network Architecture: OP Stack and Sequencer Design

Frequently Asked Questions

01.What is Base built on?

Base is an Ethereum Layer 2 built on the OP Stack, the modular rollup stack developed by Optimism. It is EVM-equivalent, which means contracts that run on Ethereum mainnet run on Base without modification. The OP Stack splits the node into op-node for consensus and L2 chain derivation, op-geth for execution, op-batcher for posting transaction batches to L1, and op-proposer for posting output roots. Base went to public mainnet on August 9 2023 and inherits the Bedrock architecture that OP Mainnet shipped on June 6 2023.

02.How does the Base sequencer work?

Base runs a single centralised sequencer in 2024, the same model OP Mainnet uses. The sequencer orders incoming L2 transactions, builds L2 blocks with op-geth, and gives users a soft confirmation within roughly two seconds. op-batcher then compresses those blocks into channels and frames and posts them to an L1 inbox as calldata, while op-proposer posts output roots to the L2OutputOracle contract. Decentralised sequencing is on the OP Stack roadmap but has not shipped. Censorship resistance comes from forced inclusion through L1 deposit transactions.

03.Are fault proofs live on Base?

No. As of January 2024 fault proofs are not yet live on Base or OP Mainnet. Cannon, the OP Stack fault prover, is in development and the dispute path remains permissioned. The security model therefore relies on the security council and upgrade keys rather than a permissionless fraud proof. Builders must treat this honestly: bridge withdrawals and state finality currently depend on social trust in the operator set and the upgrade governance, not on a live on-chain proof of fault.