CashboardGlossary · Onchain
What is a sequencer?
A sequencer is the node that orders transactions on a rollup, confirms them almost at once and later posts them to Ethereum in batches.
How does a sequencer work?
On most Ethereum L2s one operator decides the order of every transaction. Its sequencer takes what users send, builds the blocks and gives wallets an early confirmation, then batches the result to Ethereum, where it joins the permanent record. Arbitrum's docs call that early answer a provisional confirmation that depends on the sequencer behaving honestly. For a trade it is usually enough.
Coinbase runs the sequencer on Base, and Offchain Labs runs the one on Arbitrum One. The fees users pay are, in growthepie's words, collected by the chain's sequencers, so a sequencer is a business as well as a single point of failure. The failure part is not theoretical. On August 5, 2025, Base produced no blocks for 33 minutes after a handoff to a backup sequencer failed.
What keeps a sequencer honest is a way around it. On OP Stack chains you can send a transaction to the OptimismPortal contract on Ethereum, and the chain has to include it within a 12-hour sequencing window. Arbitrum lets you force one in through its delayed inbox after 24 hours. Both routes are slow on purpose. They are there for outages and censorship, and nobody uses them to trade.
Picture a made-up halt at 14:00, just as you want to sell. Nothing confirms, and an explorer shows the same last block for minutes. Forcing the sale in through Ethereum could still leave it waiting until 02:00 the next day on an OP Stack chain, and the price will not wait with it.
Also called: L2 sequencer, rollup sequencer, centralized sequencer.
Where does a sequencer show up in Cashboard?
Cashboard does not say who runs a sequencer. It shows what a stopped one looks like. Chain status reads the newest block on Ethereum and on each L2 you add, and marks an L2 row Lagging once that block is 15 seconds old and Stalled at 90 (Ethereum gets 30 and 120). A stuck public RPC looks the same from outside, so check a second source before you blame the chain. Chain pulse calls Base or Robinhood Chain stalled after a minute without a block. On the L2 scoreboard, Fees is what users paid each chain on the day, the revenue its sequencer collects, and Cost is the median transaction, both growthepie data used under CC BY 4.0.
Frequently asked questions
What happens when an L2 sequencer goes down?
Blocks stop, and anything you send waits. Your funds stay where they were. Most rollups let you force a transaction in through Ethereum, within a 12-hour window on OP Stack chains and after 24 hours on Arbitrum, so the escape hatch is real but slow. Base's 33-minute halt on August 5, 2025 started with a failed sequencer handoff.
Who runs the sequencer on Base and Arbitrum One?
Coinbase runs Base's and Offchain Labs runs Arbitrum One's. Arbitrum's own docs say its sequencer can reorder transactions or hold one back for up to 24 hours, but can do nothing to compromise the chain's safety.
Related terms
Last reviewed . Market data in Cashboard comes from the providers named on each widget and may be delayed. Nothing here is financial advice.