Spack vs tox

Spack is a package manager for installing scientific software on supercomputers, Linux, macOS, and Windows. It is designed for large supercomputing centers that share software across clusters and varied architectures, and is available at free. Users can choose package versions, compiler choices, target architectures, and compile-time options, while controlling direct and transitive dependencies. Spack can build stacks that combine Python or R packages with C, C++, or Fortran libraries. Each distinct package and dependency configuration receives its own prefix, so different builds can coexist without a new installation disrupting an existing one. Software can be installed to a user-selected directory without administrator privileges. Spack primarily builds customized software from source and also supports binary installation through build caches. It supports lockfiles, environment management, and private registries. Package recipes are Python scripts, and the `spack create` command generates starter boilerplate. The project is distributed under either the MIT license or Apache License 2.0, at the user's option.

tox is a free, open-source command-line tool for creating virtual environments, checking package builds and installations across different environments, and running tests in them. It can orchestrate test runners, linters, formatters, documentation generators, and build or publishing tools. As a continuous-integration frontend, tox combines CI workflows with shell-based testing and reduces boilerplate. Configuration can be stored in tox.toml, tox.ini, pyproject.toml, or toxfile.py. By default, it removes host environment variables unless allowed through pass_env and adjusts PATH so commands use the active environment. The command-line tool requires Python 3.10 or higher. Installation guidance covers pipx, uv, and pip, with apt and brew package-manager routes also documented. Plugins include tox-gh-actions for GitHub Actions, tox-uv for faster package installation, and tox-gh for enhanced GitHub integration. It runs on Linux, macOS, and Windows and is maintained as a volunteer open-source project.