Arbitrum
Optimistic rollup on Ethereum (Arbitrum One) built on the Offchain Labs Nitro stack, governed by ARB holders.
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Arbitrum key facts
| Category | Layer 2 network |
|---|---|
| Chains | Ethereum L2 |
| Platforms | Web, API |
| Fees | L2 network fee plus parent chain (L1) data poster fee |
| Token | ARB (governance) |
| Company | Offchain Labs (Nitro implementation) |
| Open source | Yes (github.com/OffchainLabs/nitro) |
What is Arbitrum?
Arbitrum One is an optimistic rollup on Ethereum running the Offchain Labs Nitro software. Users pay a network fee for L2 resources and a poster fee for parent chain data. Withdrawals to Ethereum pass a challenge period of 45,818 blocks, about 6.4 days, so the full exit takes about 7 days.
Arbitrum pros and cons
- BoLD dispute protocol resolves challenges within a fixed period
- Nitro node code is public on GitHub
- Censorship timeout lets users force inclusion if the Sequencer stalls
- Withdrawals to Ethereum take about 7 days
- Sequencer is still centralized per Arbitrum docs, with decentralization a long-term goal
- Withdrawal claims must be executed manually on Ethereum
Arbitrum FAQ
What is Arbitrum?
Arbitrum One is an optimistic rollup on Ethereum running the Offchain Labs Nitro software. Users pay a network fee for L2 resources and a poster fee for parent chain data. Withdrawals to Ethereum pass a challenge period of 45,818 blocks, about 6.4 days, so the full exit takes about 7 days.
Which chains does Arbitrum support?
Ethereum L2.
How much does Arbitrum cost?
L2 network fee plus parent chain (L1) data poster fee, according to Arbitrum’s own page (checked Sep 26, 2026).
Sources
How this page works
Sources: Arbitrum: official site, Arbitrum: Gas and fees, Arbitrum DAO: Conceptual overview. Data as of Sep 26, 2026.
Not affiliated with any project listed. Educational content, not financial advice.