Layer 2

Arbitrum

An optimistic rollup that scales Ethereum.

Executes transactions off-chain and posts their data to Ethereum, with interactive fraud proofs to challenge invalid state. Arbitrum One is EVM-compatible, and Stylus adds contracts in Rust and other languages that compile to WebAssembly.

Type: Layer 2
Maintained by: Offchain Labs / Arbitrum DAO
License: BSL 1.1 (Nitro)
Articles: 1

ArbitrumIntermediate

How do rollups work? Optimistic vs ZK rollups explained

Rollups execute off-chain and post data to Ethereum. Optimistic rollups like Arbitrum assume validity unless a fault proof wins during a challenge window; ZK rollups post a validity proof per batch.

#scaling#zero-knowledge

Deepak Tewatia · 5 min

Sep 14, 2026