Python UV: The Fastest Python Package Manager
#python#uv
nikeasyanzi

nikeasyanzi @nikeasyanzi

Joined:
Jul 29, 2021

Python UV: The Fastest Python Package Manager

Publish Date: Jun 28
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It's been a headache to manage Python packages. But I feel I am saved from that when I meet UV.

Introduction

There are two main concerns related to the Python package management problem.

  • Python version: Different projects may need different Python interpreters. No one wants to mix them with the system default Python interpreters.

  • The packages/libraries needed by the project: Intuitively, different projects have different library dependencies. Even if they all rely on a popular library such as OpenSSL, they may depend on different library versions.

Some tools are trying to solve the problem.
For example,

  • venv and pip provide package management but are unable to switch between different versions of Python.

  • Pyenv solves the Python version switching problem but does not support package management.

UV is developed and aimed at solving the aforementioned issues.

Here, I walk through how to use uv to manage your project.

Walkthrough

Installation

For macOS and Linux. I would use

curl -LsSf https://astral.sh/uv/install.sh | sh
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or through brew for macOS

brew install uv
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Important files

The are some key files for UV to manage the project dependency.
In addition, the good news is UV automatically generates and updates these files. Let's take a quick look.

  • .python-version: contains the Python version used for the project

  • pyproject.toml: serves as the main configuration file for project metadata and dependencies.

  • uv.lock: Lock files for dependency management in UV.

Initialization 

$ uv init my-uv
Initialized project `my-uv` at `/Users/craigyang/workplace/my-uv`

$ cd my-uv

$ tree -a -L 1
.
├── .git
├── .gitignore
├── .python-version
├── main.py
├── pyproject.toml
└── README.md

2 directories, 5 files
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Running Python scripts with UV

Let's take a look on the main.py

$ cat main.py
def main():
    print("Hello from my-uv!")


if __name__ == "__main__":
    main()
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While executing the main.py, a virtual environment is created automatically.

$ uv run main.py
Using CPython 3.13.4
Creating virtual environment at: .venv
Hello from my-uv!
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Updating dependencies

Here, we use requests as a new library to be added. We can see the content pyproject.toml is also updated.

$ uv add requests
Resolved 6 packages in 605ms
Prepared 2 packages in 223ms
Installed 5 packages in 10ms
 + certifi==2025.4.26
 + charset-normalizer==3.4.2
 + idna==3.10
 + requests==2.32.4
 + urllib3==2.4.0
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$ cat pyproject.toml
[project]
name = "my-uv"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13"
dependencies = [
    "requests>=2.32.4",
]
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Managing Python Versions in UV

In the following prompt, we see that for the my-uv project, Python3.13 is the default option, while in the system, it is installed with Python3.9.6

$ uv python list
cpython-3.14.0b1-macos-aarch64-none                 <download available>
cpython-3.14.0b1+freethreaded-macos-aarch64-none    <download available>
cpython-3.13.4-macos-aarch64-none                   /opt/homebrew/bin/python3.13 -> ../Cellar/python@3.13/3.13.4/bin/python3.13
cpython-3.13.4-macos-aarch64-none                   /opt/homebrew/bin/python3 -> ../Cellar/python@3.13/3.13.4/bin/python3
cpython-3.13.4-macos-aarch64-none                   /Users/craigyang/.local/share/uv/python/cpython-3.13.4-macos-aarch64-none/bin/python3.13
cpython-3.13.4+freethreaded-macos-aarch64-none      <download available>
cpython-3.12.11-macos-aarch64-none                  <download available>
cpython-3.11.13-macos-aarch64-none                  <download available>
cpython-3.10.18-macos-aarch64-none                  <download available>
cpython-3.9.23-macos-aarch64-none                   <download available>
cpython-3.9.6-macos-aarch64-none                    /usr/bin/python3
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Export requirements in UV 

 uv export -o requirements.txt
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Conclusion

We have shown how to use uv to start a new project.
I also recommend a comprehensive article about uv for people interest in this topic.

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