Arbitrum One ¹

Ethereum's largest L2 by ecosystem depth, where GMX invented perps-on-L2 and dozens of projects launched their own Orbit L3s. The rollup that chose interactive fraud proofs over ZK to ship first and dominate DeFi.

Unique Position Arbitrum lets developers write smart contracts in Rust/C++ through Stylus, making compute-heavy apps 10x cheaper than Solidity-only chains. While Optimism builds a unified Superchain, Arbitrum enables anyone to launch customizable L3s using Orbit. The only L2 with both massive DeFi liquidity and a thriving L3 ecosystem.

Primary Use Cases

• DeFi protocols requiring deepest L2 liquidity pools
• Compute-intensive applications leveraging Stylus WASM
• Projects launching their own Orbit L3 chains
• Perpetual trading and derivatives platforms
• Gaming studios needing customizable infrastructure

Ecosystem Character Mature DeFi ecosystem with native protocols like GMX and Camelot rather than Ethereum clones. Strong builder culture spawning dozens of Orbit chains. Community values technical innovation over marketing, evident in Stylus adoption and BoLD protocol development. The "serious DeFi" L2 where protocols launch first.

Trade-offs

• Centralized sequencer with theoretical censorship risk
• 7-day withdrawal delay for optimistic fraud proof window
• Verifier whitelist prevents fully permissionless validation
• Ecosystem fragmenting as successful projects migrate to Orbit L3s
• Higher fees than Alt-L1s and newer L2s prioritizing cheap transactions

Technical Details

Architecture Optimistic rollup with interactive multi-round fraud proofs that isolate disputed computation steps. Nitro stack runs custom Arbitrum Virtual Machine supporting EVM bytecode plus Stylus WASM contracts. Orbit framework enables deploying customized L3s with different gas tokens and parameters.

Performance Transaction costs 10-50x cheaper than Ethereum L1 but higher than ultra-low-cost chains like Nova or Polygon. Handles highest aggregate throughput in Ethereum ecosystem when including Orbit chains. Calldata compression and batching optimize costs while maintaining security guarantees.

Security & Trust Model Inherits Ethereum security through fraud proofs with 7-day challenge window. BoLD protocol prevents delay attacks through execution history commitments. Posts compressed transaction data to Ethereum L1 ensuring data availability. Interactive fraud proofs more capital efficient than single-round systems but require active validators.

Control & Governance Offchain Labs operates the centralized sequencer with no firm decentralization timeline. Arbitrum DAO controls protocol upgrades and treasury through on-chain governance. Verifier whitelist controlled by security council, preventing permissionless validation despite technical capability.