Spire is a modular L3 network built on top of zkEVM L2s, scaling Ethereum in a fractal fashion.Spire provides the infrastructure for a broad set of developers to spin up their own appchain L3s that are interoperable with one another. So Spire is a type of Rollup-as-a-service(RaaS), and also a L3-as-a-service.Unlike other Raas, Spire focuses on L3 on top zkEVMs. Through its recursive zkrollup architecture, L3s spun up with Spire can scale vertically and are also equipped with a special power that taps into contracts on L2s such as Scroll.In addition, Spire itself will introduce its own L3 that empowers other appchains on Spire.