Nox vs uv

Nox is a free, open-source command-line tool for automating tests across multiple Python environments. Projects configure sessions in a standard Python file named noxfile.py. Each session can create a virtual environment, install chosen dependencies, and run commands in sequence. Sessions can target multiple Python interpreters, with a separate environment for each interpreter, and can vary dependency or database values through parameters. Nox supports venv, uv, conda, mamba, micromamba, and virtualenv backends. Tags organize sessions and select which ones to run. Helpers load dependencies from pyproject.toml files and PEP 723 scripts. Nox runs on Linux, macOS, and Windows and installs through pip or pipx. Its tutorial documents the wntrblm/nox GitHub Action for CI installation and Python-version selection. The project describes its scope as Python testing and recommends other tools for broader task execution. Its homepage says more than 3,000 projects use Nox.

uv is a Python package and project manager for Linux, macOS, and Windows. Written in Rust, it manages dependencies and environments, with lockfiles and workspaces, and can install, list, pin, or uninstall Python versions. It also runs scripts with dependencies and runs or installs command-line tools from Python packages. Its pip-compatible interface is intended to cover work done by tools such as pip, pip-tools, pipx, poetry, pyenv, twine, and virtualenv, though its commands do not exactly match those tools. The documentation describes uv as 10–100x faster than pip. It supports source distributions, wheels, requirements.txt, and pylock.toml, as well as offline installation and private registry authentication. For package selection, its default first-index strategy limits candidates to the first index where a package is found. Credentials are not stored in uv.lock, but uv currently stores them in a plaintext file; native system secret storage is an experimental preview. The free plan is free.