Astral UV

UV is an extremely fast Python package installer and resolver written in Rust.

Quick Reference

Project Management

Initialize a new project:

uv init my-project
cd my-project

Add dependencies (updates pyproject.toml automatically):

uv add requests httpx
uv add --dev pytest ruff

Sync environment with lockfile:

uv sync

Running Code

Run scripts without manual venv activation:

uv run python script.py
uv run pytest
uv run ruff check .

Run with inline dependencies:

uv run --with requests script.py

Virtual Environments

uv venv                    # Create .venv
uv venv --python 3.12      # Specific Python version

pip Interface

Drop-in pip replacement (10-100x faster):

uv pip install requests
uv pip install -r requirements.txt
uv pip compile requirements.in -o requirements.txt

Python Version Management

uv python install 3.12     # Install Python version
uv python list             # Show available versions
uv python pin 3.12         # Pin version for project

Best Practices

1. Prefer uv add over uv pip install for project dependencies
2. Use uv run instead of activating venvs manually
3. Commit uv.lock to version control
4. Use uv sync --frozen in CI for reproducible builds
5. Add dev dependencies with uv add --dev