The team spent some time looking at layer-2 technologies from Arbitrum, Optimism and zkSync before settling on Matter Labs’ ZK Stack, Whittaker initially told CoinDesk, but the team later clarified that they were looking at zero-knowledge rollups. The ZK Stack is a customizable software toolkit that lets developers spin up their own chains based on zkSync’s technology. A key component of the ZK stack, as well as other ZK rollups, is that it uses zero-knowledge proofs, a type of cryptography that’s one of hottest trends in blockchain.