The Arbitrum Foundation, the organization behind Ethereum’s leading Layer 2 network, has unveiled a new program enabling the launch of bespoke Layer 2 and Layer 3 networks built on top of the Arbitrum Orbit tech stack.

Announced on Jan. 18, the Arbitrum Expansion Program allows participants to launch customized rollup chains leveraging the Arbitrum Orbit stack. Users can modify Orbit to build Layer 2s that settle on the Ethereum mainnet, or Layer 3 networks that leverage Arbitrum or other Ethereum Layer 2s for finalization.

“Projects are eager to modify the Arbitrum stack according to their business needs and run their own instance of the Orbit software,” the announcement said. “The Orbit deployment tool comes built-in with a host of customization options, and developers can go even deeper than that and use the codebase to make deep customizations.”

The program facilitates the development of chains featuring custom gas tokens, native account abstractions, and alternative data availability solutions. The foundation added that all Orbit-based rollups must settle transactions to the Ethereum mainnet, or other networks that derive their security from Ethereum.

The Arbitrum Foundation noted that users can freely and permissionlessly customize Orbit-based Layer 3 networks built on top of the Arbitrum One and Nova L2s, but other deployments must share revenue with the Arbitrum DAO.

“Participants are expected to contribute a portion of their profits back to the Arbitrum ecosystem,” the Arbitrum Foundation said. “Via the permissionless revenue sharing model of the Program, Orbit chains are free to customize L2s or L3s that settle to Ethereum, including on top of non-Arbitrum chains. L3s that settle to Arbitrum One and Nova are still covered by the existing free, permissionless path.”

The revenue-sharing is initially set at 10%, with 8% going to the Arbitrum DAO and 2% supporting the newly-launched Arbitrum Developer Guild. The guild will distribute funding to guild members to incentivize the ongoing development of Aribtrum’s core technology.

The price of ARB is down 5% in the past 24 hours, according to CoinGecko.

Competition heats up between Ethereum scaling teams

The Expansion Program is Arbitrum’s answer to initiatives from rival Ethereum scalability teams that allow developers to modify and deploy bespoke versions of their respective core technologies.

In June 2023, Optimism’s Bedrock upgrade launched the OP Stack, an open-source technology stack allowing developers to launch custom Layer 2 networks. Optimism said it will enable interoperability between OP Stack-based chains in the future, establishing a unified ecosystem of Layer 2s dubbed the “Superchain.”

Chains leveraging Optimism’s technology now make up four of the top five L2s by total value locked (TVL), accounting for $8B or nearly 38% of the $21.2B combined Layer 2 TVL, according to L2 beat. For comparison, Arbitrum One chain hosts a $10.8B TVL, equating to a 51% dominance.

Matter Labs, the team behind ZkSync Era, also joined the fray with its zero-knowledge ZK Stack last June. Matter Labs similarly said the modular tech stack lays the groundwork for a symbiotic ecosystem of ZK Stack-based “Hyperchains.”

Aribtrum added that it is currently exploring different solutions to facilitate interoperability between Orbit-based chains.

Polygon also launched its Chain Development Kit (CDK) in September, allowing developers to create custom zero-knowledge chains leveraging its technology stack.