pip-tools vs tox

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.

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.