uv Documentation (Repost)

  docs.astral.sh · Astral

Reposted from the uv documentation by Astral, last updated 2026-03-13. Copyright (c) 2025 Astral Software Inc., used under the MIT License; the full notice is at the end of this post.

An extremely fast Python package and project manager, written in Rust.

Installing Trio's dependencies with a warm cache.

Highlights

• A single tool to replace pip, pip-tools, pipx, poetry, pyenv, twine, virtualenv, and more.
• 10-100x faster than pip.
• Provides comprehensive project management, with a universal lockfile.
• Runs scripts, with support for inline dependency metadata.
• Installs and manages Python versions.
• Runs and installs tools published as Python packages.
• Includes a pip-compatible interface for a performance boost with a familiar CLI.
• Supports Cargo-style workspaces for scalable projects.
• Disk-space efficient, with a global cache for dependency deduplication.
• Installable without Rust or Python via curl or pip.
• Supports macOS, Linux, and Windows.

uv is backed by Astral, the creators of Ruff.

Installation

Install uv with our official standalone installer:

macOS and Linux

$ curl -LsSf https://astral.sh/uv/install.sh | sh

Windows

PS> powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

Then, check out the first steps or read on for a brief overview.

Tip

uv may also be installed with pip, Homebrew, and more. See all of the methods on the installation page.

Projects

uv manages project dependencies and environments, with support for lockfiles, workspaces, and more, similar to rye or poetry:

$ uv init example
Initialized project `example` at `/home/user/example`

$ cd example

$ uv add ruff
Creating virtual environment at: .venv
Resolved 2 packages in 170ms
   Built example @ file:///home/user/example
Prepared 2 packages in 627ms
Installed 2 packages in 1ms
 + example==0.1.0 (from file:///home/user/example)
 + ruff==0.5.4

$ uv run ruff check
All checks passed!

$ uv lock
Resolved 2 packages in 0.33ms

$ uv sync
Resolved 2 packages in 0.70ms
Checked 1 package in 0.02ms

See the project guide to get started.

uv also supports building and publishing projects, even if they’re not managed with uv. See the packaging guide to learn more.

Scripts

uv manages dependencies and environments for single-file scripts.

Create a new script and add inline metadata declaring its dependencies:

$ echo 'import requests; print(requests.get("https://astral.sh"))' > example.py

$ uv add --script example.py requests
Updated `example.py`

Then, run the script in an isolated virtual environment:

$ uv run example.py
Reading inline script metadata from: example.py
Installed 5 packages in 12ms
<Response [200]>

See the scripts guide to get started.

Tools

uv executes and installs command-line tools provided by Python packages, similar to pipx.

Run a tool in an ephemeral environment using uvx (an alias for uv tool run):

$ uvx pycowsay 'hello world!'
Resolved 1 package in 167ms
Installed 1 package in 9ms
 + pycowsay==0.0.0.2
  """

  ------------
< hello world! >
  ------------
   \   ^__^
    \  (oo)\_______
       (__)\       )\/\
           ||----w |
           ||     ||

Install a tool with uv tool install:

$ uv tool install ruff
Resolved 1 package in 6ms
Installed 1 package in 2ms
 + ruff==0.5.4
Installed 1 executable: ruff

$ ruff --version
ruff 0.5.4

See the tools guide to get started.

Python versions

uv installs Python and allows quickly switching between versions.

Install multiple Python versions:

$ uv python install 3.10 3.11 3.12
Searching for Python versions matching: Python 3.10
Searching for Python versions matching: Python 3.11
Searching for Python versions matching: Python 3.12
Installed 3 versions in 3.42s
 + cpython-3.10.14-macos-aarch64-none
 + cpython-3.11.9-macos-aarch64-none
 + cpython-3.12.4-macos-aarch64-none

Download Python versions as needed:

$ uv venv --python 3.12.0
Using CPython 3.12.0
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate

$ uv run --python pypy@3.8 -- python
Python 3.8.16 (a9dbdca6fc3286b0addd2240f11d97d8e8de187a, Dec 29 2022, 11:45:30)
[PyPy 7.3.11 with GCC Apple LLVM 13.1.6 (clang-1316.0.21.2.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>>

Use a specific Python version in the current directory:

$ uv python pin 3.11
Pinned `.python-version` to `3.11`

See the installing Python guide to get started.

The pip interface

uv provides a drop-in replacement for common pip, pip-tools, and virtualenv commands.

uv extends their interfaces with advanced features, such as dependency version overrides, platform-independent resolutions, reproducible resolutions, alternative resolution strategies, and more.

Migrate to uv without changing your existing workflows — and experience a 10-100x speedup — with the uv pip interface.

Compile requirements into a platform-independent requirements file:

$ uv pip compile requirements.in \
   --universal \
   --output-file requirements.txt
Resolved 43 packages in 12ms

Create a virtual environment:

$ uv venv
Using CPython 3.12.3
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate

Install the locked requirements:

$ uv pip sync requirements.txt
Resolved 43 packages in 11ms
Installed 43 packages in 208ms
 + babel==2.15.0
 + black==24.4.2
 + certifi==2024.7.4
 ...

See the pip interface documentation to get started.

Learn more

See the first steps or jump straight to the guides to start using uv.

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License

This post reproduces the uv documentation home page (docs/index.md in astral-sh/uv). uv is dual-licensed under MIT or Apache-2.0; this repost uses the MIT License:

MIT License

Copyright (c) 2025 Astral Software Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.