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Run Any Python CLI Instantly — No Install, No Virtualenv (uvx)

By Audrey Roy Greenfeld • Thu, Oct 2, 2025

If you need to run Python applications from PyPI without installing them permanently, uvx provides a convenient way to execute Python tools without having to manage dependencies manually.

TL;DR: Run PyPI CLI tools on-demand in an ephemeral virtualenv — no permanent installs, no virtualenv management. Quick try: uvx pyclean . or uvx ruff@latest check. Great for one-offs, CI, demos, and reproducible one-line workflows.

What is uvx?

uvx is a command-line tool from the uv package manager that allows you to run Python CLI tools from PyPI directly, without installing them permanently on your system.

A quick note on how uvx fits into the ecosystem: unlike pipx (which installs and keeps isolated apps around), uvx creates a disposable environment for each run so you don't accumulate installed CLI tools. That makes it ideal for ad-hoc tasks, CI steps, and scripts where you want a clean environment every time.

Using uvx

To run any Python tool from PyPI, you would run:

uvx tool_name [tool-options]

Example: pyclean

For example, to run pyclean on the current directory to clean up your *.pyc files and __pycache__ dirs:

uvx pyclean .

Example: Instaloader

To download an Instagram post with shortcode DPIzsnAEvNX, you run:

uvx instaloader -- -DPIzsnAEvNX

Instaloader then creates a directory called -DPIzsnAEvNX containing:

  • The .jpg from that Instagram post
  • Its accompanying text
  • A .json.xz file - compressed JSON metadata about the post

Example: Cookiecutter

Or to run Cookiecutter, if the current directory is a Cookiecutter template that you want to generate starting project boilerplate from:

uvx cookiecutter .

Example: Latest Version of Ruff

I thought by default uvx <tool> would always install the latest version of the tool, but it seems to cache the first version it installs. So if you want to ensure you always get the latest version, you can specify @latest like:

uvx ruff@latest check

This runs the latest version of ruff to check your code for linting issues.

Better Living With uvx

In short, it makes your Python CLI tools work better:

  • No need to create a virtual env
  • No need to install tools permanently
  • Clean execution environment for each run, with auto-cleanup after
  • Easy access to any Python CLI tool on PyPI
  • Avoids dependency conflicts with existing packages

Security & Tradeoffs

A few things to keep in mind:

  • Running code directly from PyPI executes arbitrary code. Do your due diligence knowing what you run, and be careful where you run unknown code!
  • uvx caches the first version it installs for a package; use @latest when you explicitly want the newest release.
  • Ephemeral runs mean a small startup latency compared to a permanently installed binary, and you need network access for first-run installs. I'm fine with it honestly.

Cool Uses

I don't do all this yet, but AI tells me uvx is great for:

  • In CI to keep build images small and avoid baking in lots of CLI tools.
  • In Justfiles and deploy scripts for reproducible commands without installing system-wide tools.