pip-tools vs Spack

pip-tools is a free set of command-line tools for keeping pinned pip-based packages current and making builds more predictable. Its two core commands are pip-compile and pip-sync. pip-compile generates requirements.txt files from pyproject.toml, setup.cfg, setup.py, or requirements.in, and can handle project and optional dependencies in pyproject.toml. It can also generate hashes for pip hash-checking mode. pip-sync installs, upgrades, or removes packages to make a virtual environment match a compiled requirements.txt file. Defaults can be configured in .pip-tools.toml or pyproject.toml, and pip-compile can be used as a pre-commit hook. The tools support Linux, macOS, and Windows, and the package requires Python 3.9 or later. Compilation results may differ across operating systems, Python versions, and implementations, so the project advises compiling separately for each target environment. The default backtracking resolver is described as more robust but generally slower; the legacy resolver is deprecated. pip-tools is distributed under the BSD License.

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.