A High-Speed Python Package Installer Written in Rust

Astral has released uv, a Python package installer, and resolver written in Rust, designed to replace pip and pip-tools workflows. Uv is part of Astral’s pursuit of a comprehensive Python project and package manager that is fast, reliable, and easy to use. The company is also taking stewardship of Rye, an experimental Python packaging tool from Armin Ronacher, with plans to expand uv into a unified successor project. Uv is 8-10x faster than pip and pip-tools without caching and 80-115x faster when running with a warm cache. It supports Linux, Windows, and macOS.

Introduction to uv: A Python Package Installer and Resolver

Astral, a company known for creating high-performance developer tools for the Python ecosystem, has recently released a new tool called uv. This tool is a Python package installer and resolver, written in Rust, and is designed to replace pip and pip-tools workflows. The creation of uv marks a significant step towards Astral’s goal of developing a comprehensive Python project and package manager that is fast, reliable, and easy to use.

uv’s Performance and Adoption

One of the key principles behind uv’s implementation is a strong focus on performance. Benchmarks show that uv is significantly faster than pip and pip-tools, both with and without caching. This is achieved by using a global module cache to avoid re-downloading and re-building dependencies, and leveraging Copy-on-Write and hardlinks on supported filesystems to minimize disk space usage.

In addition to its performance, uv is also optimized for adoption. Its initial release supports the pip and pip-tools APIs, making it usable by existing projects with zero configuration. uv can be used as a resolver, a virtual environment creator, a package installer, and more. It is both unified and modular, and ships as a single static binary capable of replacing pip, pip-tools, and virtualenv.

uv’s Features and Compatibility

uv supports a wide range of features expected from a modern Python packaging tool, including editable installs, Git dependencies, URL dependencies, local dependencies, constraint files, source distributions, and custom indexes. It is designed to be compatible with existing tools and has been tested at-scale against the public PyPI index.

uv also introduces new capabilities, such as alternate resolution strategies, resolutions against arbitrary target Python versions, and dependency “overrides”. However, it is important to note that uv may not be suitable for all projects, as it lacks support for some legacy features of pip, such as .egg distributions.

uv and Rye: Towards a Unified Python Package and Project Manager

The development of uv is part of Astral’s larger vision of creating a “Cargo for Python”: a unified Python package and project manager that is extremely fast, reliable, and easy to use. This vision aligns closely with that of Rye, an experimental project and package management tool from Armin Ronacher. As such, Astral has taken over Rye and plans to evolve uv into a production-ready “Cargo for Python”, providing a smooth migration path from Rye to uv when the time is right.

Future Plans for uv

Following the release of uv, Astral’s first priority is to support users as they consider adopting uv, with a focus on improving compatibility, performance, and stability across platforms. From there, the company plans to expand uv into a complete Python project and package manager. Despite the ambitious roadmap for uv, even in its current form, it offers a significantly different experience for Python developers.