The developer firm behind the Worldcoin protocol shared Tuesday that its upcoming layer-2 chain, World Chain, is open for developers to use.

This means that select developers can apply to build, test, and give feedback to Tools For Humanity, the developer firm behind Worldcoin, according to a press release shared with CoinDesk.

World Chain has tapped Optimism’s OP Stack, a customizable toolkit that lets developers build their own blockchains using Optimism’s technology, to build out its own network. OP Stack has become a popular choice for creating layer-2 chains, and was used by Coinbase to build its ‘Base’ network.

“I think they're a visionary, the team behind it, they have been at this for a while,” said Remco Bloemen, the head of blockchain at the Worldcoin Foundation, the non-profit organization supporting Worldcoin, in an interview with CoinDesk.

World Chain is expected to open to users later this summer, according to earlier reporting from CoinDesk. Bloemen wouldn’t give an exact timeline for when mainnet will go live, but said they aren’t planning to open a testnet for users.

“This is going to evolve into mainnet at some point. But it's just an opportunity for people to test their infrastructure and be ready for when this turns into mainnet,” Bloemen told CoinDesk

In addition, the World Chain project would operate Reth, a new Ethereum client software that was developed by venture capital firm Paradigm, in shadow mode, and Tools for Humanity plans to commit engineering resources to have Reth ready for mainnet.

Reth is a new client for the Ethereum network, developed by Paradigm, with an emphasis on being “user-friendly, modular, fast, and efficient,” according to Paradigm’s website . While Reth is typically used for the Ethereum network, Paradigm shared that it will accommodate a broad user base including layer-2 networks like Optimism.

Read more: Worldcoin, Sam Altman's Crypto Project, Is Building a Layer-2 Chain