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Optimistic Rollup

A rollup that assumes off-chain transactions are valid by default and relies on a fraud-proof challenge window instead of cryptographic proofs.

FBFenwei BianAuthorVZVictor ZhouEditorJuly 2, 2026
  • glossary

An optimistic rollup is a type of rollup that "assume[s] offchain transactions are valid and don't publish proofs of validity for batches of transactions," relying instead on a fraud-proof challenge system to catch errors. After a batch of transactions is posted to layer 1, a challenge window—commonly around seven days—opens during which anyone running a full node can dispute the batch with a fraud proof; if unchallenged, the batch is treated as final. That window is why withdrawing funds from an optimistic rollup back to Ethereum normally takes about a week, unlike a ZK rollup, which finalizes as soon as its validity proof is verified. Arbitrum, Optimism, and Base are the largest optimistic rollups by usage. For tokenized domains held on an optimistic rollup, that challenge window is a practical detail worth knowing: a transfer can be usable immediately on the rollup but not fully final against layer 1 until the window closes.

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Contributors

Fenwei Bian

Software Developer & Writer • Namefi
Author

Fenwei Bian is a software developer in her thirties who spends her working hours in pull requests and her weekends with her hands in soil or sawdust. Years of open source on GitHub taught her that names are interfaces: a good one is clear, honest about what it does, and kind to whoever has to use it next.

She gardens because it rewards patience and punishes wishful thinking, and she does woodwork because a joint either fits or it doesn't. Both habits show up in how she writes about naming — measure twice, check the source, and don't sand over a rough spot and hope no one notices.

For Namefi she writes about how domain markets actually move, the practical trade-offs of tokenizing and flipping names, and picking a domain you'll still be glad you own in twenty years.

GitHub

Victor Zhou

Founder & Standards Editor • Namefi
Editor

Victor Zhou is a technology founder and standards editor focused on digital identity and trust. He founded Namefi, edits Ethereum Improvement Proposals, and previously led smart-contract architecture work at Google Labs.

His work sits at the intersection of naming, ownership, and the systems people use to establish identity online. That perspective makes him especially interested in the way names move between personal meaning, public recognition, and digital infrastructure.

For Namefi, Victor edits and writes about domains as durable digital identity: how names become ownable onchain assets, how tokenization changes custody and trust, and what naming can learn from the systems people use to establish identity online.

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