uv

uv is an extremely fast Python package and project manager. It replaces pip,

pip-tools, pipx, pyenv, virtualenv, poetry, etc.

When to use uv

Always use uv for Python work, especially if you see:

• The uv.lock file

• uv headers in requirements* files, e.g., "This file was autogenerated by uv"

Don't use uv in projects managed by other tools:

• Poetry projects (identifiable by poetry.lock file)

• PDM projects (identifiable by pdm.lock file)

Choosing the right workflow

Scripts

Use when: Running single Python files and standalone scripts.

Key commands:

uv run script.py                      # Run a script

uv run --with requests script.py      # Run with additional packages

uv add --script script.py requests    # Add dependencies inline to the script

Projects

Use when: There is a pyproject.toml or uv.lock

Key commands:

uv init                   # Create new project

uv add requests           # Add dependency

uv remove requests        # Remove dependency

uv sync                   # Install from lockfile

uv run <command>          # Run commands in environment

uv run python -c ""       # Run Python in project environment

uv run -p 3.12 <command>  # Run with specific Python version

Tools

Use when: Running command-line tools (e.g., ruff, ty, pytest) without

installation.

Key commands:

uvx <tool> <args>            # Run a tool without installation

uvx <tool>@<version> <args>  # Run a specific version of a tool

Important:

• uvx runs tools from PyPI by package name. This can be unsafe - only run

well-known tools.

• Only use uv tool install only when specifically requested by the user.

Pip interface

Use when: Legacy workflows with requirements.txt or manual environment

management, no uv.lock present.

Key commands:

uv venv

uv pip install -r requirements.txt

uv pip compile requirements.in -o requirements.txt

uv pip sync requirements.txt

# Platform independent resolution

uv pip compile --universal requirements.in -o requirements.txt

Important:

• Don't use the pip interface unless clearly needed.

• Don't introduce new requirements.txt files.

• Prefer uv init for new projects.

Migrating from other tools

pyenv → uv python

pyenv install 3.12       → uv python install 3.12

pyenv versions           → uv python list --only-installed

pyenv local 3.12         → uv python pin 3.12

pyenv global 3.12        → uv python install 3.12 --default

pipx → uvx

pipx run ruff            → uvx ruff

pipx install ruff        → uv tool install ruff

pipx upgrade ruff        → uv tool upgrade ruff

pipx list                → uv tool list

pip and pip-tools → uv pip

pip install package      → uv pip install package

pip install -r req.txt   → uv pip install -r req.txt

pip freeze               → uv pip freeze

pip-compile req.in       → uv pip compile req.in

pip-sync req.txt         → uv pip sync req.txt

virtualenv .venv         → uv venv

Common patterns

Don't use pip in uv projects

# Bad

pip install requests

# Good

uv add requests

Don't run python directly

# Bad

python script.py

# Good

uv run script.py

# Bad

python -c "..."

# Good

uv run python -c "..."

# Bad

python3.12 -c "..."

# Good

uvx python@3.12 -c "..."

Don't manually manage environments in uv projects

# Bad

python -m venv .venv

source .venv/bin/activate

# Good

uv run <command>

Documentation

For detailed information, read the official documentation:

• https://docs.astral.sh/uv/llms.txt

The documentation links to specific pages for each of these workflows.