X11n

X11n is an open-source project that provides an alternative implementation of the X Window System. Designed as a modular and extensible successor to X11, X11n aims to preserve compatibility with existing X11 clients while introducing modern features such as built-in compositing, improved security, and enhanced network performance.

Origin and development: The project began in 2016 by researchers and developers seeking to address core limitations of X11, including security vulnerabilities, architectural complexity, and lagging support for contemporary GPUs. The first public release appeared in 2019, followed by major updates in 2021 and 2023. As of 2024, development continues under the X11n Project, with active contributions from several independent maintainers.

Architecture and features: X11n uses a modular server architecture with separate core protocol handling, rendering, and input pathways. It provides a compatibility layer that allows existing X11 clients to operate with little or no modification, while also offering a modern client library for new applications. Features include a built-in compositor with hardware acceleration, improved multi-monitor and fractional scaling support, sandboxed client execution, and encrypted, authenticated network transport. The design emphasizes reducing latency, bandwidth usage, and susceptibility to eavesdropping.

Platform support and reception: X11n targets Linux and Unix-like systems, with ports to BSD variants and experimental Windows builds. Adoption remains limited compared to established stacks, with usage concentrated in research environments and some experimental distributions. While it strives for wide compatibility, certain legacy X11 extensions and applications may require workarounds.

See also: X Window System, X.Org Server, Wayland, XCB.