Nixpkgs Package Collection

Nixpkgs is the free and open-source package collection for the Nix package manager and NixOS Linux distribution, containing over 100,000 package definitions written in the Nix expression language. Maintained by the NixOS community since 2003 (created alongside Nix by Eelco Dolstra), Nixpkgs is one of the largest and most active open-source package repositories, frequently surpassing Debian, Arch Linux AUR, and Homebrew in package count and update frequency. Key features: over 100,000 packages spanning every category of software: programming languages, development tools, desktop applications, server software, games, libraries, and system utilities. Reproducible builds: every package is defined as a Nix derivation that specifies all inputs (source code, dependencies, build tools) deterministically. Given the same inputs, the build produces identical output. Multi-platform: each package supports multiple system types (x86_64-linux, aarch64-linux, x86_64-darwin, aarch64-darwin) via a unified cross-compilation framework. Channels and flakes: packages are distributed via channels (named branches that auto-update) or flakes (hermetic inputs). Binary caches on cache.nixos.org provide pre-built binaries for common configurations. Overlays: layer custom modifications on top of the default package set without forking. Module system: the NixOS module system defines system configuration options (services, users, networking, hardware) as reusable modules. Testing infrastructure: NixOS VM tests spin up networks of virtual machines to test multi-node configurations. Continuous integration: Hydra builds every package on every commit across all supported platforms. MIT.