Pixi: Multi-Language Package and Workflow Manager

Pixi is a cross-platform package manager and workflow tool that manages both conda-forge packages and PyPI packages from a single project manifest. It replaces conda’s global environment model with project-local environments and automatic lock files.

When to use pixi

Use pixi when your project depends on native libraries that conda-forge packages more reliably than PyPI: CUDA toolkits, GDAL, HDF5, OpenCV, MKL, NetCDF. Some of these have PyPI packages, but conda-forge bundles the underlying C/C++/Fortran libraries so you don’t need to install them separately. Pixi also works well for mixed-language projects (Python + R, Python + C++) and for teams that want reproducible cross-platform lock files covering both conda and PyPI dependencies.

For pure Python projects, uv provides a simpler workflow.

Installation

curl -fsSL https://pixi.sh/install.sh | bash

iwr -useb https://pixi.sh/install.ps1 | iex

This installs the pixi binary to ~/.pixi/bin (macOS/Linux) or %UserProfile%\.pixi\bin (Windows). See the official installation guide for other methods.

Project setup

Initialize a new project with pixi init:

pixi init my-project
cd my-project

This creates a pixi.toml manifest:

[workspace]
authors = ["Your Name <you@example.com>"]
channels = ["conda-forge"]
name = "my-project"
platforms = ["osx-arm64"]  # auto-detected from your system
version = "0.1.0"

[dependencies]

[tasks]

To use pyproject.toml instead (useful if you’re building a Python package):

pixi init --format pyproject my-project

With pyproject.toml, pixi configuration lives under [tool.pixi.*] sections (e.g. [tool.pixi.workspace], [tool.pixi.dependencies]), while standard [project] metadata remains portable to other Python tools.

Managing dependencies

Conda packages

pixi add python numpy pandas

PyPI packages

pixi add --pypi requests

Pixi resolves conda dependencies first, then resolves PyPI packages against what conda already installed. It uses uv internally for PyPI resolution.

Installing the environment

pixi install

This creates a .pixi/ directory containing the project environment. The directory is local to the project and should be added to .gitignore (pixi does this automatically on pixi init).

Running commands

# Run a command in the project environment
pixi run python main.py

# Start an interactive shell
pixi shell

Tasks

Pixi includes a built-in task runner. Tasks are defined in pixi.toml and run within the project environment.

# Add tasks
pixi task add test "pytest -s"
pixi task add lint "ruff check ."

# Run a task
pixi run test

Tasks can also be defined directly in pixi.toml with dependencies on other tasks:

[tasks]
lint = "ruff check ."
test = { cmd = "pytest -s", depends-on = ["lint"] }

Multi-environment support

Pixi can define multiple environments from composable “features.” Each feature is a named set of dependencies; environments combine one or more features. Named environments include the default feature’s dependencies unless you set no-default-feature = true.

[dependencies]
python = ">=3.12"
numpy = ">=2.0"

[feature.test.dependencies]
pytest = ">=8"

[feature.docs.dependencies]
sphinx = ">=7"

[environments]
test = ["test"]
docs = ["docs"]

Run commands in a specific environment:

pixi run --environment test pytest
pixi run --environment docs sphinx-build docs build

Cross-platform lock files

Pixi resolves dependencies for all target platforms in a single pixi.lock file. Add platforms with:

pixi workspace platform add linux-64 win-64

The lock file captures the full dependency graph for every platform and environment combination. Each platform is solved separately, so exact builds may differ across OSes, but every collaborator gets a reproducible install for their platform.

Tool management

Like pipx or uvx, pixi can install CLI tools globally or run them in temporary environments:

# Install a tool globally
pixi global install ruff

# Run a tool without installing it
pixi exec black --check .

# List globally installed tools
pixi global list

Other useful commands

# Search for a package on configured channels
pixi search opencv

# Show the dependency tree
pixi tree

# Show environment and system info
pixi info

# Update dependencies to latest compatible versions
pixi update

Learn more

• Pixi documentation
• Pixi GitHub repository
• Switching from conda to pixi