Optimistic rollups
Optimistic rollups accept proposed state changes subject to a dispute process that can demonstrate incorrect execution.
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A USEFUL DISTINCTION
Optimistic vs validity rollups
Different ways to establish that an offchain state transition is acceptable.
| Look at | Optimistic rollup | Validity rollup |
|---|---|---|
| Core approach | State claims can be disputed through a fault-proof process. | State transitions are accompanied by validity proofs. |
| Verification dependency | Working challenges, participants, and dispute rules. | Proof-system soundness, circuits, verifier implementation. |
| Withdrawal considerations | Often includes a challenge period for canonical exits. | Requires proof and settlement processing; not necessarily instant. |
| Shared requirements | Accessible transaction data and functioning settlement contracts. | Accessible transaction data and functioning settlement contracts. |
| Remaining controls | Sequencers, upgrades, emergency powers, and bridge design. | Sequencers, upgrades, emergency powers, and bridge design. |
ethereum.org contributors · Optimistic rollups ↗Checked 13 Nov 2026Optimism contributors · Fault proofs explainer ↗Checked 13 Nov 2026ethereum.org contributors · Zero-knowledge rollups ↗Checked 13 Nov 2026ethereum.org contributors · Data availability ↗Checked 13 Nov 2026ethereum.org contributors · Validium ↗Checked 13 Nov 2026
THE KEY DISTINCTION
What to carry forward
A proof category alone does not establish the maturity or decentralization of a deployed rollup. Inspect its actual controls and escape mechanisms.
MAKE IT CONCRETE
A worked perspective
A fast sequencer acknowledgment can precede settlement in either architecture. The reader should distinguish local acceptance from the base chain’s finalized state.
Follow the underlying mechanisms
Validity proofs and rollups
A validity rollup proves that an offchain state transition follows specified rules before the settlement contract accepts it.
Data availability
A compact commitment can identify data without supplying it. Verification and independent recovery require the necessary data to be obtainable.