Based Rollup (L1-sequenced)

A based rollup is a layer-2 scaling solution for Ethereum that uses the layer-1 blockchain’s validators for transaction sequencing, enhancing decentralization and alignment with Ethereum’s security model.

What is a Based Rollup?

Based rollups, also known as L1-sequenced rollups, are a specialized type of Ethereum layer-2 solution where transaction ordering and sequencing are handled directly by Ethereum’s layer-1 validators rather than a dedicated, often centralized sequencer.

Proposed by Ethereum Foundation researcher Justin Drake in March 2023, this approach inherits Ethereum’s liveness guarantees, censorship resistance, and decentralization, addressing key pain points in traditional rollups like potential sequencer failures or MEV (maximum extractable value) capture by single entities. Transactions enter the shared mempool visible to Ethereum’s searchers, builders, and proposers, who include them in L1 blocks permissionlessly, ensuring no special permissions are needed and aligning the rollup’s block order with Ethereum’s.

This model promotes synchronous composability across based rollups, allowing smart contracts on different L2s to interact in near-real-time within the same Ethereum block, reviving Ethereum’s “money legos” vision for seamless DeFi interoperability without asynchronous bridges. Economically, based rollups route MEV back to Ethereum validators, reducing costs by eliminating sequencer signature overheads and fostering better incentive alignment—for instance, Taiko, the first based rollup to launch its mainnet in June 2024, returns approximately five times more revenue to Ethereum than centralized sequencer rollups like Base or Arbitrum. Taiko, built as a Type-1 zkEVM, processes transactions off-chain using zero-knowledge proofs while leveraging Ethereum’s sequencing, achieving up to 100,000 TPS in tests and fees under $0.01, with over 1 million active addresses and $500 million in TVL as of 2025.

This design addresses Ethereum’s layer-2 fragmentation by realigning L2s with L1, potentially enabling up to thousands of transactions per second with fees as low as fractions of a cent, as seen in prototypes like Ethrex’s upcoming based rollup mode. However, based rollups may face challenges like dependency on L1 block times for sequencing, which could limit speed compared to centralized sequencers, though innovations in preconfirmation tech, as in Puffer, aim to make withdrawals near-instant.