Arbitrum review

Overview

Arbitrum is a Layer 2 network for Ethereum. It processes transactions on its own, cheaply and quickly, and then posts the results to Ethereum, which keeps them secure. It was built by Offchain Labs, a company founded by Princeton computer scientists, and its main network, Arbitrum One, launched in 2021.

Arbitrum quickly became one of the biggest Layer 2s, home to DeFi apps such as GMX, Aave and Uniswap. In 2023 it launched the ARB token and handed control of the network’s treasury and rules to the Arbitrum DAO, a community of token holders.

How it works

Arbitrum is an optimistic rollup. It bundles thousands of transactions together and posts them to Ethereum, assuming (“optimistically”) that they are correct. Anyone can challenge a wrong result during a dispute window of about a week; if they prove fraud, the wrong result is thrown out.

Since 2025, a system called BoLD lets anyone take part in these challenges, rather than only an approved list, which makes Arbitrum more trustless. Arbitrum also offers Stylus, which lets developers write apps in popular languages like Rust, not just Ethereum’s Solidity.

For users, Arbitrum feels like Ethereum, with the same wallets and apps, but transactions cost a cent or less. The trade-off: withdrawing directly to Ethereum takes about a week, though bridges and exchanges can do it faster for a fee.

Arbitrum chains and Robinhood Chain

Companies can use Arbitrum’s technology to launch their own chains, which settle to Ethereum. In return, many of them share part of their revenue with the Arbitrum DAO.

The biggest example is Robinhood Chain, which reached public mainnet on 1 July 2026. Built by the trading app Robinhood for tokenized stocks and other assets, it sends 10% of its net protocol revenue back to the Arbitrum ecosystem, 8% to the DAO treasury. Its launch sent ARB sharply higher over the summer.

The ARB token

ARB is a governance token: holders vote on how the DAO spends its treasury and on upgrades. Fees on Arbitrum are paid in ETH, not ARB, and revenue flows to the DAO, not directly to token holders. This is the main criticism of ARB: the network can do well without the token benefiting much.

Tokens set aside for the team and early investors are released every month. In September 2026, about 92.6 million ARB were unlocked. The last of these unlocks is expected in March 2027, after which selling pressure should ease.

Security and reliability

Arbitrum’s core technology has a good record and has been audited extensively. The main risks are:

• Upgrade powers. A Security Council of 12 members can make emergency changes. This protects users against bugs but means the system isn’t fully trustless yet.
• Sequencer outages. Arbitrum uses one main sequencer, run by Offchain Labs, to order transactions. It has gone down a few times, most notably for over an hour in December 2023 during a wave of “inscription” transactions. Funds remain safe in these cases, and users can still post transactions directly to Ethereum.
• App risk. As on any chain, DeFi apps built on Arbitrum can be hacked.

Money deposited in DeFi apps on Arbitrum stood at about $1.4 billion in October 2026, according to DeFiLlama, well below its earlier peaks.

Arbitrum vs. the competition

Base, run by Coinbase, has become the busiest Layer 2 by users. Optimism powers Base and many other chains through its OP Stack. Arbitrum’s edge is its deep DeFi, mature technology and Robinhood Chain.

Our verdict

Arbitrum is one of the most important pieces of Ethereum’s scaling plan: mature, widely used and now powering Robinhood’s blockchain. As a network, it is a success.

As an investment, ARB is harder to love. It is mainly a voting token, revenue goes to the DAO rather than holders, unlocks continue until 2027, and the price is more than 90% below its high. ARB is a high-risk bet on Arbitrum’s ecosystem growing and on the DAO finding ways to reward holders. Invest only what you can afford to lose.

This review is for information only and is not financial advice.