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) |
ARB token
- Price
- $0.1698 +2.2% 24h
- Market cap
- $1.2B
- Fully diluted value
- $1.7B
- 30-day change
- -5.2%
Market data: CoinGecko, updated Nov 8, 2026. Educational content, not financial advice.
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.
How Arbitrum works
A Sequencer orders transactions on Arbitrum One and posts them to Ethereum in compressed batches.
Each fee has two parts. The poster fee repays the batch poster for Ethereum data: every transaction is compressed alone with Brotli, the size is multiplied by 16 to estimate its data units, and an adaptive price per unit keeps the fees collected close to the poster's real costs. The network fee covers L2 computation and storage at the current base fee.
Arbitrum One validation follows the BoLD protocol, so any node that implements BoLD can join and challenge an invalid state claim. Chain ownership sits with the ArbitrumDAO, where ARB holders and their delegates vote. A 12-member Security Council, elected by the DAO, can act through a 9-of-12 multisig in emergencies and for minor upgrades.
How to start with Arbitrum
- Install a web3 wallet such as MetaMask and add Arbitrum One: RPC arb1.arbitrum.io/rpc, chain ID 42161, currency ETH, explorer arbiscan.io.
- Most major exchanges let you withdraw ETH straight to Arbitrum.
- You can also deposit from Ethereum at bridge.arbitrum.io: connect, pick the source and destination networks, choose the token and press Move funds.
- Deposits arrive in roughly 15 to 30 minutes.
- Arbitrum One supports two forms of USDC, native and bridged, so check which one you will receive before you deposit.
- Keep some ETH on the source chain for gas, or the wallet prompt will not appear.
Arbitrum fees and limits
- Above the gas target it rises exponentially: going 1% over the target adds a 10% fee, and 2% over adds 15%.
You pay the L2 base fee times gas used, plus the poster fee converted into L2 gas units. The base fee has a floor, readable through the getMinimumGasPrice method on ArbGasInfo. Because the poster fee follows Ethereum data prices, eth_estimateGas can return different values over time.
Risks to know before using Arbitrum
- The Arbitrum Foundation runs the Sequencer for Arbitrum One.
- It can delay a transaction by up to 24 hours and reorder transactions over short periods, but it cannot change state or block a transaction forever.
- If 9 of the 12 Security Council members were compromised, funds could be at risk.
- For a malicious proposal passed through the DAO, users have several weeks to withdraw to Ethereum before it takes effect.
- Offchain Labs says its Nitro code is audited by several independent firms and sponsors a multi-million dollar bug bounty.
- It still warns that undiscovered bugs could put funds at risk.
- Withdrawals through the Arbitrum bridge take at least seven days to reach Ethereum.
- Anyone can deploy contracts on Arbitrum, so the docs advise treating its apps exactly as you would on Ethereum.
Arbitrum alternatives
Other projects people compare with Arbitrum.
Ethereum layer 2 network built by Coinbase, with no native token and ETH used for gas.
zkEVM rollup on Ethereum incubated within Consensys, with ETH for gas and a LINEA burn token.
Optimistic rollup on Ethereum and reference chain of the open-source OP Stack.
Gaming-focused Ethereum layer 2 on the OP Stack, launched by Sky Mavis, with RON as its gas and staking token.
Validity rollup on Ethereum using STARK proofs and the Cairo language, with fees paid in STRK.
ZK rollup on Ethereum that proves every operation with zero-knowledge proofs, with its own EraVM.
Where Arbitrum ranks on DappAtlas
Listed next to Arbitrum
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).
Does Arbitrum have a token?
Yes, ARB. Its market cap was $1.2B on CoinGecko on Nov 8, 2026. Educational content, not financial advice.
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.