conda-lock vs Nox

conda-lock is a lightweight library for producing reproducible lockfiles for conda environments. It solves dependencies separately for each target platform, allowing installations from generated lockfiles to avoid running the conda solver. Inputs can come from environment.yml, conda-build meta.yaml, or pyproject.toml dependency specifications. Its default unified lockfile covers multiple platforms and can be rendered into other lockfile formats. Documented target examples include Linux, macOS, Windows, and additional Linux architectures. The project describes use alongside conda, mamba, pip, Docker, and pixi, and provides installation routes through pip, conda, and mamba; pipx or condax are recommended for isolated installation. Mixed conda-and-pip locking is experimental. Channel access supports token or basic authentication, with environment-variable substitution for credentials. The unified lockfile can omit raw credential-bearing channel URLs when it matches credential portions to environment variables, although rendered explicit lockfiles may contain substituted variables. Private pip repository support is limited to legacy PyPI repositories using basic authentication. The software is MIT-licensed and free.

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.