Nix

Nix is a purely functional package manager and build system designed for reproducibility, reliability, and declarative system configuration.

Created in 2003 by Eelco Dolstra, Nix ensures package management without side effects by using a unique store and dependency isolation.

It enables users to define entire system configurations using the Nix Expression Language, allowing for deterministic builds and rollback capabilities.

Nix is widely used in the NixOS Linux distribution, where it provides atomic upgrades, declarative package management, and sandboxed builds.