NixOS

OpenBSD is a free Unix-like operating system developed with security as the first priority, known for relentless code auditing, safe defaults, and inventing widely used tools like OpenSSH. It suits firewalls, routers, and servers where correctness beats convenience. Hardware support and application availability are narrower than Linux, and performance is not its focus.

postmarketOS is a real Linux distribution for smartphones, built on Alpine Linux, aiming to give phones a ten-year lifespan instead of vendor-dictated obsolescence. It frees old hardware from abandoned Android builds and Google services entirely. Device support varies enormously, and on most phones calls, camera, or power management remain works in progress.

Debian is a fully community-governed Linux distribution known for stability, a strict free-software policy, and a package archive of tens of thousands of programs. It is the foundation under Ubuntu, Mint, and most self-hosted servers, with no company that can change direction on you. Stable releases ship older software by design.

Fedora is a Linux distribution that ships current open-source software on a roughly six-month cycle, serving as the upstream community project for Red Hat Enterprise Linux. It balances modern tooling with a strong free-software policy and good defaults. Releases are supported for about thirteen months, so regular upgrades are part of the deal.