Xen Project

The Xen Project produces a type-1 (bare-metal) hypervisor that runs directly on hardware, not on top of an operating system. This design gives it strong isolation between virtual machines and near-native performance. The project started at the University of Cambridge in the early 2000s and later became a Linux Foundation Collaborative Project. Major public clouds including Amazon AWS and many hosting providers run Xen under the hood. It supports paravirtualization, which lets guest operating systems communicate efficiently with the hypervisor without needing full hardware emulation. Full hardware-assisted virtualization is also available for unmodified operating systems like Windows. Xen works with x86, ARM, and other architectures. The toolset includes xl (the default management tool), libxl (the library interface), and support for live migration, PCI passthrough, and GPU virtualization. The project maintains a regular release cadence, with the latest stable version being 4.18. Documentation is thorough but can be dense for newcomers. If you need a battle-tested hypervisor for large-scale production workloads and value open governance, Xen is a solid choice.