Arbitrum Orbit AnyTrust Chains

Olivia Jurkowitz
Offchain Labs
Published in
6 min readAug 17, 2023

Written by Lee Bousfield and Olivia Jurkowitz — August 17, 2023

TL;DR: Today we’re making it easier than ever to launch Arbitrum Orbit AnyTrust chains. You can now use the Orbit documents and deployment portal to create a devnet AnyTrust chain that hosts EVM-compatible smart contracts. Orbit Anytrust chains enable ultra low-cost transactions for high-volume use cases.


Arbitrum AnyTrust technology is one of the two technologies that you can use today to build Arbitrum Orbit chains (the other being Arbitrum Rollup). Starting today, you can use our open-source deployment tool to launch a local AnyTrust chain that settles to Arbitrum Goerli.

As a refresher, Arbitrum Orbit chains are dedicated chains that settle to one of Arbitrum’s Layer 2 chains: Arbitrum One, Arbitrum Nova, or Arbitrum Goerli for testnets.

You own your Orbit chain and can customize its privacy, permissions, fee token, governance, and more. By creating an Orbit chain you are joining the largest Ethereum L2 ecosystem of protocols, communities, and partners. Learn more here.

With increasing interest in deploying Orbit chains, we wanted to go over the core benefits of launching an AnyTrust chain in particular, and some new developments to look forward to.

Arbitrum Orbit Deployment Portal

Who is AnyTrust for?

AnyTrust technology was purpose-built for high-volume use cases. Examples of these include:

  • Gaming: Users can mint items on-chain at a high frequency, from currency to personalized assets. The recently announced Xai chain is being built specifically for on-chain games.
  • Social: Social projects that seek to record interactions on-chain can do so sustainably. For example, Reddit’s community points system operates on Arbitrum Nova, an AnyTrust chain.
  • Finance: Companies and protocols with high infrastructure costs can move some of their infra to an Anytrust chain. For example, Premia Finance launched their orderbook on Nova to reduce costs for placing signed orders.

In addition to the examples above, there are new use cases that will be enabled by the high-speed and low-cost of AnyTrust technology. Let us know about the novel use cases you are building by contacting us.

Why Should I Choose AnyTrust?

AnyTrust chains enable 1. lower costs in exchange for a minimal extra trust assumption, and 2. faster withdrawals of non-fungible assets, all while benefiting from Ethereum’s security.

1. Significantly lower transaction costs, ~30–150x cheaper than L1

With Rollup technology, chains put all transaction data on the Ethereum chain as calldata, to ensure that everyone can get the transaction data if they need it. That’s the biggest cost of operating a Rollup chain.

AnyTrust chains however, rely on a Data Availability Committee (DAC) to store calldata. If a quorum of DAC members says that they are storing some transaction data and will provide it to others on demand, then the chain doesn’t need to put that data on Ethereum. This is because the AnyTrust honesty assumption guarantees that there is an honest DAC member who will provide the data to anyone who needs it.

That’s how AnyTrust lowers the cost of L2 transactions.

2. Faster withdrawals — from days to minutes (coming soon)

No longer wait 7 days for confirmation. In a Rollup, a validator’s claim about the outcome of transactions must remain pending for a week, so that any validator will have a chance to challenge that claim. That’s why withdrawals (and L2-to-L1 transactions more generally) take a week.

Later this year, alongside our work on the BOLD Protocol, AnyTrust chains will be able to immediately confirm and execute transactions. If a quorum of DAC members says that a claim about transaction outcomes is correct, that claim can be confirmed and executed immediately, because the AnyTrust honesty assumption guarantees that an honest committee member stands behind the claim.

That’s how AnyTrust makes withdrawals faster.

3. Custom Fee Tokens (coming soon)

Support for custom fee tokens will be formally added to Arbitrum Nitro in the coming weeks. Initial support will be targeted at AnyTrust chains since the cost of posting data to the settlement layer is incredibly cheap. We’re working on a sustainable model for Rollup chains as well, particularly around managing exchange rates, and will share more details when ready.

This feature allows chains to receive a native ERC20 token as payment for transaction fees instead of ETH. In practice, the fee token will be escrowed on in the bridge contract on the parent chain (Arbitrum One or Nova for Orbit chains) and it will be minted on the Orbit chain as native currency. This feature further enables value capture and flexibility for project teams and their ecosystems.

4. Built on Ethereum, with extremely strong security guarantees

A chain is operated by a committee of nodes, with a minimal assumption about how many committee members are honest. As an example, there might be 20 committee members, and an assumption that at least two of them are honest.

This is a much smaller trust assumption compared to conventional BFT sidechains, which require more than ⅔ of the members–that would be 14 out of 20–to be honest. We can reduce the trust requirement from 14 to 2 because of the “fallback to rollup” feature, built on top of Ethereum as explained below.

How does AnyTrust technology differentiate from Rollup technology?

Arbitrum Rollup is an Optimistic Rollup protocol; it is trustless and permissionless. Part of how these properties are achieved is by requiring all chain data to be posted on Layer 1. This means the availability of this data follows directly from the security properties of Ethereum itself, and, in turn, that any party can participate in validating the chain and ensuring its safety.

By contrast, Arbitrum AnyTrust introduces a trust assumption in exchange for lower fees; data availability is managed by a Data Availability Committee (DAC), a fixed, permissioned set of entities. We introduce some threshold, K, with the assumption that at least K members of the committee are honest. For simplicity, we’ll hereby assume a committee of size 20 and a K value of 2:

If 19 out of the 20 committee members and the Sequencer are malicious and colluding together, they can break the chain’s safety (and, e.g., steal users’ funds); this is the new trust assumption.

If anywhere between 2 and 18 of the committee members are well-behaved, the AnyTrust chain operates in “Rollup mode”; i.e., data gets posted on L1.

In what should be the common and happy case, the system operates without posting the L2 chain’s data on L1, and thus, users pay significantly lower fees. This is the core upside of AnyTrust chains over rollups.

Differences between Rollup and AnyTrust

What is the fallback to Rollup feature?

If there isn’t a cooperative quorum, then an AnyTrust chain operates as a regular rollup. Data will be posted on the L1 Ethereum chain, and withdrawals will have a delay period, just like on a standard rollup–until the committee resumes operation, and then the chain will switch seamlessly back to the cheaper, faster mode. The switch between “quorum mode” and “rollup mode” happens seamlessly, in both directions.

How do I start building with AnyTrust technology?

For step-by-step instructions that walk you through the process of configuring and launching your own AnyTrust Orbit devnet chain, visit the Quickstart guide or visit the Orbit chain deployment portal directly.

As a reminder, our deployment portal is focused on testing and experimentation, guiding you through the process of launching your own devnet. If you’re interested in launching a mainnet chain or have feedback on the process generally, feel free to get in touch with our team.