nixos/nixpkgs

Nixpkgs is the official package collection for the Nix package manager and the foundation of NixOS, a Linux operating system. It contains definitions for over 120,000 software packages, not the software itself, but instructions written in the Nix language that tell the Nix package manager exactly how to build and install each one. The central idea behind Nix is "purely functional" package management. Unlike traditional package managers that modify a shared system state, Nix builds each package in isolation and stores results in a content-addressed path. This means installing or upgrading one package cannot accidentally break another, and you can roll back to any previous state easily. NixOS extends this idea to an entire operating system: the whole system configuration, including services, users, and installed software, is declared in Nix expressions, so the system can always be reproduced exactly from source. You would use Nixpkgs if you want to install software via the Nix package manager on Linux or macOS, if you are running or building a NixOS system, or if you want to contribute a new package to the ecosystem. The repository is one of the most active on GitHub and is written entirely in the Nix language.