Arbitrum Nova.

Arbitrum Nova is an Ethereum layer-2 chain built on Arbitrum's AnyTrust protocol, a variant of the Nitro rollup stack that stores transaction data with a Data Availability Committee instead of publishing all of it to Ethereum. It shares the same execution engine as Arbitrum One, so contracts written in Solidity deploy to Arbitrum Nova without modification, but it makes a different choice about where data lives after a transaction executes. That choice is what lets everyday actions on Arbitrum Nova cost a small fraction of what the same action costs on a full rollup, which matters most to applications that run thousands of cheap transactions rather than a handful of expensive ones.

Built on the Nitro stack

Arbitrum Nova runs the same Nitro technology that powers Arbitrum One: a WASM-based fraud-proof system, Ethereum-equivalent execution, and the same developer tooling described in the Arbitrum documentation. The difference is confined almost entirely to how transaction data is made available, not how transactions are executed or verified.

Why a second chain instead of one setting

Arbitrum One and Arbitrum Nova exist side by side rather than as one configurable chain because the data-availability choice carries a trust trade-off that not every application wants to make. Separating them lets a DeFi protocol stay on the fully trust-minimized chain while a game or social app that cannot tolerate rollup-level fees opts into Arbitrum Nova instead.

The core difference between Arbitrum Nova and Arbitrum One is where transaction data is stored after a batch executes. Arbitrum One posts that data to Ethereum as calldata, inheriting Ethereum's full security for data availability. Arbitrum Nova instead hands that job to a committee of known, reputable entities who store the data and sign attestations that it is available on request. Everything else — the sequencer, the fraud-proof window, the bridge back to Ethereum — follows the same Nitro design on both chains.

Aspect	Arbitrum Nova	Arbitrum One
Data availability	Data Availability Committee (off-chain)	Full calldata on Ethereum
Typical fees	Sub-cent for most actions	Low, but higher than Nova
Security model	Rollup security + committee trust assumption	Rollup security, no added committee
Best fit	Gaming, social, high-volume apps	DeFi, high-value transfers
Fallback if committee fails	Can post data to Ethereum directly	Not applicable

AnyTrust is the protocol that defines Arbitrum Nova's approach to data availability, and understanding it is the key to understanding why fees stay so low. Rather than asking every Ethereum node to store a chain's full transaction history, AnyTrust asks a smaller, accountable group to vouch for it.

The Data Availability Committee

Arbitrum Nova's committee is a fixed set of members — typically well-known infrastructure and crypto organizations — who each hold a copy of batch data and sign a certificate confirming it is available. A transaction only needs a defined threshold of committee signatures to be considered final, which the independent risk tracking on L2BEAT documents in detail alongside other rollups and sidechains.

What happens if the committee doesn't respond

If the committee cannot produce the requested data, Arbitrum Nova falls back to posting that data on Ethereum directly, the same way Arbitrum One always does. This fallback is what keeps Nova's trust assumption bounded rather than open-ended: the committee can make the chain cheap, but it cannot make data permanently unavailable without the chain reverting to Ethereum-level costs for that batch.

Arbitrum Nova was purpose-built for applications where transaction volume is the defining constraint, not transaction value. A handful of categories make up most of its real-world usage.

• On-chain games that need every move, craft, or trade recorded cheaply enough to feel instant
• Social applications with frequent posts, likes, or tips that would be uneconomical on a full rollup
• Micro-payment and tipping systems moving small amounts at high frequency
• NFT platforms minting large collections where per-item gas matters
• Loyalty and rewards programs that issue many small on-chain credits

Reddit's Community Points

Arbitrum Nova gained early visibility through Reddit's Community Points program, which used it to distribute token rewards to large subreddit communities — a workload defined by volume rather than value, and exactly the profile Nova was designed to serve cheaply.

What doesn't belong on Nova

High-value transfers, lending, and other DeFi activity generally stay better suited to Arbitrum One or Ethereum itself, where every byte of data availability carries Ethereum's full security guarantee. Arbitrum Nova trades a sliver of that guarantee for cost, which is the right trade for volume-driven apps but not for protocols securing large sums.

Arbitrum Nova's ecosystem is smaller and more specialized than Arbitrum One's, concentrated around gaming studios, social platforms, and NFT projects rather than general DeFi. Bridging into Arbitrum Nova works through the same canonical Arbitrum bridge used for Arbitrum One, and assets can move between the two chains by routing back through Ethereum. Activity on the chain can be verified directly through the Nova explorer, which shows live blocks, contracts, and transactions the same way Etherscan does for Ethereum.

Choosing Arbitrum Nova means accepting one additional assumption beyond what a full rollup like Arbitrum One asks of you, and it is worth being precise about what that assumption is and is not.

What stays the same as Ethereum

Execution correctness on Arbitrum Nova is still enforced by fraud proofs that settle on Ethereum, the same mechanism ethereum.org's layer-2 overview describes for optimistic rollups generally. No one — not the sequencer, not the committee — can forge a valid state transition or steal funds locked in the bridge.

What the committee adds

What the Data Availability Committee changes is who you rely on to retrieve transaction data, not who verifies that data once retrieved. If enough committee members were to collude or disappear, users could be temporarily unable to reconstruct recent state until the fallback to Ethereum kicks in — a narrow, well-defined risk rather than a path to lost funds.

Using Arbitrum Nova looks like using any other Arbitrum chain: connect a self-custody wallet, add the Nova network, and bridge ETH or supported tokens in through the canonical Arbitrum bridge. Gas is still paid in ETH, just a far smaller amount than the same action would cost on Arbitrum One or Ethereum. Developers deploying to Arbitrum Nova use the same contracts, the same RPC interface, and the same tooling covered in background references on Arbitrum's architecture, with only the network endpoint changing.