Optimistic rollup
ORU
An L2 that posts state roots to L1 and assumes them valid unless a fraud proof is submitted within a challenge window.
Optimistic rollups (Arbitrum, Optimism, Base) trade slower withdrawals (typically 7 days) for cheaper computation than ZK rollup (zero-knowledge rollup)s. Withdrawal-queue depth and sequencer-decentralisation roadmaps factor into the StableLens chain risk score.
Related terms
- ZK rollup (zero-knowledge rollup)An L2 that posts validity proofs to L1, enabling near-instant withdrawals and stronger trust assumptions than optimistic rollups.
- L2 (Layer-2)A scaling network that inherits security from an L1 by posting state roots back — rollups, validiums, plasma.
- RollupAn L2 architecture that batches transactions off-chain and posts compressed state + proofs back to L1 for settlement.
- SequencerThe entity that orders transactions on a rollup — typically centralised today, with decentralisation roadmaps in progress.