nixcrpkgs is a collection of tools for cross-compiling statically-linked, standalone software applications. With nixcrpkgs, you can specify what platforms you want to target, what libraries and build tools you depend on, and the commands that build your software. When you build your software, nixcrpkgs will automatically take care of building or retrieving everything you need, including cross-compilers and libraries. nixcrpkgs primarily consists of Nix expressions, which are recipes for building software with Nix, the purely functional package manager. These recipes build on top of the Nix Packages collection (Nixpkgs).