uv: The Fast Python Package and Project Manager

uv is a Python package and project manager written in Rust. It replaces pip, pip-tools, virtualenv, pyenv and pipx with one tool, and it's dramatically faster.

Install

curl -LsSf https://astral.sh/uv/install.sh | sh
# or: pipx install uv, brew install uv

Start a project

uv init my-api && cd my-api
uv add fastapi "uvicorn[standard]"   # adds to pyproject.toml and installs
uv add --dev pytest ruff
uv run fastapi dev main.py            # runs inside the project's environment

uv creates .venv automatically and writes a uv.lock lockfile with exact versions for every platform. Commit both pyproject.toml and uv.lock.

Reproducible installs

uv sync            # install exactly what the lockfile says
uv sync --frozen   # in CI/Docker: fail if the lockfile is out of date
uv lock --upgrade-package fastapi

Manage Python versions

uv python install 3.13 3.14
uv python pin 3.14       # writes .python-version

Run tools without installing them

uvx ruff check .
uvx --from httpie http GET https://httpbin.org/get
uv tool install ruff      # install permanently on your PATH

Single-file scripts with dependencies

# /// script
# dependencies = ["requests", "rich"]
# ///
import requests
from rich import print

print(requests.get("https://api.github.com/repos/astral-sh/uv").json()["stargazers_count"])

uv run fetch_stars.py   # uv creates a temporary environment with those packages

Coming from pip

uv pip install -r requirements.txt works as a drop-in replacement, so you can adopt uv gradually before moving to pyproject.toml and uv.lock.