Welcome to Nox

nox is a command-line tool that automates testing in multiple Python environments, similar to Tox. Unlike Tox, Nox uses a standard Python file for configuration.

Install nox via pip:

pip install --user --upgrade nox

Nox is configured via a noxfile.py file in your project’s directory. Here’s a simple noxfile that runs lint and some tests:

import nox

def tests(session):

def lint(session):
    session.run('flake8', '--import-order-style', 'google')

To run both of these sessions, just run:


For each session, Nox will automatically create virtualenv with the appropriate interpreter, install the specified dependencies, and run the commands in order.

To learn how to install and use Nox, see the Tutorial. For documentation on configuring sessions, see Configuration & API. For documentation on running nox, see Command-line usage.

Projects that use Nox

Nox is lucky to have several wonderful projects that use it and provide feedback and contributions.

Other useful projects

Nox is not the only tool of its kind. If Nox doesn’t quite fit your needs or you want to do more research, we recommend looking at these tools:

  • Tox is the de-facto standard for managing multiple Python test environments, and is the direct spiritual ancestor to Nox.
  • Invoke is a general-purpose task execution library, similar to Make. Nox can be thought of as if Invoke were tailored specifically to Python testing, so Invoke is a great choice for scripts that need to encompass far more than Nox’s specialization.


Nox is free & open-source software and is made possible by community contributors.

If you’d like to get involved, see Contributing.