Arbitrum One ¹

What is Arbitrum One?

A general-purpose optimistic rollup and the main chain of the Arbitrum ecosystem.

• Security: Inherits Ethereum security via fraud proofs. Verifier whitelist is still in place — not fully permissionless.
• Infra: Nitro stack with custom WASM EVM (Arbitrum Virtual Machine), calldata compression, and support for chain-local precompiles.
• Sequencer: Centralized and run by Offchain Labs. Censorship resistance depends on fallback L1 posting (24h+ delay).
• Cost: ~10–50x cheaper than Ethereum L1, varies with calldata usage and compression. More expensive than Nova.
• Ecosystem: Large and composable, but fragmented with the rise of Orbit chains. Main home for DeFi protocols like GMX, Radiant, and native infra.
• Governance: Arbitrum DAO controls upgrades. Security Council (9/12 multisig) can fast-track upgrades or pause the system.
• Trade-offs:
  • Fraud proofs still rely on trusted parties; challenge game not yet widely used
  • Sequencer is centralized, upgrade delay can be bypassed
  • Complexity of Nitro adds non-trivial surface area for bugs and audit requirements

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