Urbit is a personal OS designed from scratch to run peer-to-peer applications. It solves the hard problems of implementing a peer-to-peer network (including identity, NAT traversal, and exactly-once delivery) in the kernel so app developers can focus on business logic. The entire OS is a single pure function that provides application developers with strong guarantees: automated persistence and memory management, repeatable builds, and support for hot code reloading. Learn more at urbit.org.