Coordinated Sequencer
Also known as: Rollup Sequencer, Layer 2 Transaction Orderer, Batching Coordinator
An entity in rollup-based blockchains that orders transactions and proposes batches to the Layer 1 chain.
A coordinated sequencer is a centralized or semi-centralized component in Layer 2 rollup architectures responsible for ordering transactions before they are posted to the Layer 1 blockchain. This design provides low latency and high throughput but may limit decentralization. Sequencers often participate in MEV capture and can implement censorship if not monitored. Some rollups are developing decentralized sequencer sets to mitigate these risks. Coordinated sequencers are essential for UX optimization and are used in Arbitrum, Optimism, and zkSync for transaction batching and rollup submission.