Optimistic Rollup
Also known as: Layer 2 Optimistic Chain, EVM-Compatible Rollup, Fraud-Proof Rollup
A Layer 2 scaling solution that assumes transactions are valid by default and only runs fraud proofs if challenged.
Optimistic Rollups are Layer 2 scaling solutions that batch and process transactions off-chain and post the results to Ethereum, assuming they are valid unless proven otherwise. Unlike ZK-Rollups, which verify every transaction with cryptographic proofs, Optimistic Rollups allow a challenge period during which anyone can submit a fraud proof if they detect invalid behavior. This design reduces computation costs and scales Ethereum while maintaining decentralization. Popular implementations include Optimism and Arbitrum. They support EVM compatibility, fast finality, and lower gas fees, making them suitable for DeFi and dApp development.