PyO3


Rust bindings for Python, including tools for creating native Python extension modules. Running and interacting with Python code from a Rust binary is also supported.

• User Guide: stable | main

• API Documentation: stable | main

Usage

Requires Rust 1.83 or greater.

PyO3 supports the following Python distributions:

• CPython 3.9 or greater
• PyPy 7.3 (Python 3.11+)
• GraalPy 25.0 or greater (Python 3.12+)

You can use PyO3 to write a native Python module in Rust, or to embed Python in a Rust binary. The following sections explain each of these in turn.

Using Rust from Python

PyO3 can be used to generate a native Python module. The easiest way to try this out for the first time is to use <code class="ra0-md-code">maturin</code>. maturin is a tool for building and publishing Rust-based Python packages with minimal configuration. The following steps install maturin, use it to generate and build a new Python package, and then launch Python to import and execute a function from the package.

First, follow the commands below to create a new directory containing a new Python virtualenv, and install maturin into the virtualenv using Python's package manager, pip:

# (replace string_sum with the desired package name)
$ mkdir string_sum
$ cd string_sum
$ python -m venv .env
$ source .env/bin/activate
$ pip install maturin

Still inside this string_sum directory, now run maturin init. This will generate the new package source. When given the choice of bindings to use, select pyo3 bindings:

$ maturin init
✔ 🤷 What kind of bindings to use? · pyo3
  ✨ Done! New project created string_sum

The most important files generated by this command are Cargo.toml and lib.rs, which will look roughly like the following:

Cargo.toml

[package]
name = "string_sum"
version = "0.1.0"
edition = "2021"

[lib]
# The name of the native library. This is the name which will be used in Python to import the
# library (i.e. `import string_sum`). If you change this, you must also change the name of the
# `#[pymodule]` in `src/lib.rs`.
name = "string_sum"
# "cdylib" is necessary to produce a shared library for Python to import from.
#
# Downstream Rust code (including code in `bin/`, `examples/`, and `tests/`) will not be able
# to `use string_sum;` unless the "rlib" or "lib" crate type is also included, e.g.:
# crate-type = ["cdylib", "rlib"]
crate-type = ["cdylib"]

[dependencies]
pyo3 = "0.29.0"

src/lib.rs

/// A Python module implemented in Rust. The name of this module must match
/// the `lib.name` setting in the `Cargo.toml`, else Python will not be able to
/// import the module.
#[pyo3::pymodule]
mod string_sum {
  use pyo3::prelude::*;

  /// Formats the sum of two numbers as string.
  #[pyfunction]
  fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
    Ok((a + b).to_string())
  }
}

Finally, run maturin develop. This will build the package and install it into the Python virtualenv previously created and activated. The package is then ready to be used from python:

$ maturin develop
# lots of progress output as maturin runs the compilation...
$ python
>>> import string_sum
>>> string_sum.sum_as_string(5, 20)
'25'

To make changes to the package, just edit the Rust source code and then re-run maturin develop to recompile.

To run this all as a single copy-and-paste, use the bash script below (replace string_sum in the first command with the desired package name):

mkdir string_sum && cd "$_"
python -m venv .env
source .env/bin/activate
pip install maturin
maturin init --bindings pyo3
maturin develop

If you want to be able to run cargo test or use this project in a Cargo workspace and are running into linker issues, there are some workarounds in the FAQ.

As well as with maturin, it is possible to build using <code class="ra0-md-code">setuptools-rust</code> or manually. Both offer more flexibility than maturin but require more configuration to get started.

Using Python from Rust

To embed Python into a Rust binary, you need to ensure that your Python installation contains a shared library. The following steps demonstrate how to ensure this (for Ubuntu), and then give some example code which runs an embedded Python interpreter.

To install the Python shared library on Ubuntu:

sudo apt install python3-dev

To install the Python shared library on RPM based distributions (e.g. Fedora, Red Hat, SuSE), install the python3-devel package.

Start a new project with cargo new and add pyo3 to the Cargo.toml like this:

[dependencies.pyo3]
version = "0.29.0"
# Enabling this cargo feature will cause PyO3 to start a Python interpreter on first call to `Python::attach`
features = ["auto-initialize"]

Example program displaying the value of sys.version and the current user name:

use pyo3::prelude::*;
use pyo3::types::IntoPyDict;

fn main() -> PyResult<()> {
    Python::attach(|py| {
        let sys = py.import("sys")?;
        let version: String = sys.getattr("version")?.extract()?;

        let locals = [("os", py.import("os")?)].into_py_dict(py)?;
        let code = c"os.getenv('USER') or os.getenv('USERNAME') or 'Unknown'";
        let user: String = py.eval(code, None, Some(&locals))?.extract()?;

        println!("Hello {}, I'm Python {}", user, version);
        Ok(())
    })
}

The guide has a section with lots of examples
about this topic.

Tools and libraries

• maturin _Build and publish crates with pyo3, rust-cpython or cffi bindings as well as rust binaries as python packages_
• setuptools-rust _Setuptools plugin for Rust support_.
• pyo3-built _Simple macro to expose metadata obtained with the <code class="ra0-md-code">built</code> crate as a <code class="ra0-md-code">PyDict</code>_
• rust-numpy _Rust binding of NumPy C-API_
• dict-derive _Derive FromPyObject to automatically transform Python dicts into Rust structs_
• pyo3-log _Bridge from Rust to Python logging_
• pythonize _Serde serializer for converting Rust objects to JSON-compatible Python objects_
• pyo3-async-runtimes _Utilities for interoperability with Python's Asyncio library and Rust's async runtimes._
• rustimport _Directly import Rust files or crates from Python, without manual compilation step. Provides pyo3 integration by default and generates pyo3 binding code automatically._
• pyo3-arrow _Lightweight Apache Arrow integration for pyo3._
• pyo3-bytes _Integration between <code class="ra0-md-code">bytes</code> and pyo3._
• pyo3-object_store _Integration between <code class="ra0-md-code">object_store</code> and <code class="ra0-md-code">pyo3</code>._

Examples

• anise _A modern, high-performance toolkit for spacecraft mission design, notably used to help softly land Firefly Blue Ghost on the Moon on 02 Feb 2025._
• arro3 _A minimal Python library for Apache Arrow, connecting to the Rust arrow crate._
• arro3-compute _arro3-compute_
• arro3-core _arro3-core_
• arro3-io _arro3-io_
• bed-reader _Read and write the PLINK BED format, simply and efficiently._
• Shows Rayon/ndarray::parallel (including capturing errors, controlling thread num), Python types to Rust generics, Github Actions
• blake3-py _Python bindings for the BLAKE3 cryptographic hash function._
• Parallelized builds on GitHub Actions for MacOS, Linux, Windows, including free-threaded 3.13t wheels.
• cellular_raza _A cellular agent-based simulation framework for building complex models from a clean slate._
• connector-x _Fastest library to load data from DB to DataFrames in Rust and Python._
• cryptography _Python cryptography library with some functionality in Rust._
• css-inline _CSS inlining for Python implemented in Rust._
• datafusion-python _A Python library that binds to Apache Arrow in-memory query engine DataFusion._
• deltalake-python _Native Delta Lake Python binding based on delta-rs with Pandas integration._
• fastbloom _A fast bloom filter | counting bloom filter implemented by Rust for Rust and Python!_
• fastuuid _Python bindings to Rust's UUID library._
• fast-paseto _High-performance PASETO (Platform-Agnostic Security Tokens) implementation with Python bindings._
• feos _Lightning fast thermodynamic modeling in Rust with fully developed Python interface._
• finalytics _Investment Analysis library in Rust | Python._
• forust _A lightweight gradient boosted decision tree library written in Rust._
• geo-index _A Rust crate and Python library for packed, immutable, zero-copy spatial indexes._
• granian _A Rust HTTP server for Python applications._
• haem _A Python library for working on Bioinformatics problems._
• hifitime _A high fidelity time management library for engineering and scientific applications where general relativity and time dilation matter._
• html2text-rs _Python library for converting HTML to markup or plain text._
• html-py-ever _Using html5ever through kuchiki to speed up html parsing and css-selecting._
• hudi-rs _The native Rust implementation for Apache Hudi, with C++ & Python API bindings._
• inline-python _Inline Python code directly in your Rust code._
• johnnycanencrypt OpenPGP library with Yubikey support.
• jsonschema _A high-performance JSON Schema validator for Python._
• mocpy _Astronomical Python library offering data structures for describing any arbitrary coverage regions on the unit sphere._
• obstore _The simplest, highest-throughput Python interface to Amazon S3, Google Cloud Storage, Azure Storage, & other S3-compliant APIs, powered by Rust._
• opendal _A data access layer that allows users to easily and efficiently retrieve data from various storage services in a unified way._
• orjson _Fast Python JSON library._
• ormsgpack _Fast Python msgpack library._
• pdfcrate _An ergonomic, high-level PDF generation library for Rust and Python — a Prawn-style layout API for composing documents, not low-level PDF plumbing._
• polars _Fast multi-threaded DataFrame library in Rust | Python | Node.js._
• pycrdt _Python bindings for the Rust CRDT implementation Yrs._
• pydantic-core _Core validation logic for pydantic written in Rust._
• primp _The fastest python HTTP client that can impersonate web browsers by mimicking their headers and TLS/JA3/JA4/HTTP2 fingerprints._
• quebec _A database-backed background job queue for Python, inspired by Rails' Solid Queue._
• radiate: _A high-performance evolution engine for genetic programming and evolutionary algorithms._
• rateslib _A fixed income library for Python using Rust extensions._
• river _Online machine learning in python, the computationally heavy statistics algorithms are implemented in Rust._
• robyn A Super Fast Async Python Web Framework with a Rust runtime.
• rust-python-coverage _Example PyO3 project with automated test coverage for Rust and Python._
• rnet Asynchronous Python HTTP Client with Black Magic
• sail _Unifying stream, batch, and AI workloads with Apache Spark compatibility._
• tibs _A sleek Python library for binary data._
• tiktoken _A fast BPE tokeniser for use with OpenAI's models._
• tokenizers _Python bindings to the Hugging Face tokenizers (NLP) written in Rust._
• tzfpy _A fast package to convert longitude/latitude to timezone name._
• toml-rs _A High-Performance TOML v1.0.0 and v1.1.0 parser for Python written in Rust._
• utiles _Fast Python web-map tile utilities_

Articles and other media

• (Video) Using Rust in Free-Threaded vs Regular Python 3.13 - Jun 4, 2025
• (Video) Techniques learned from five years finding the way for Rust in Python - Feb 26, 2025
• (Podcast) Bridging Python and Rust: An Interview with PyO3 Maintainer David Hewitt - Aug 30, 2024
• (Video) PyO3: From Python to Rust and Back Again - Jul 3, 2024
• Parsing Python ASTs 20x Faster with Rust - Jun 17, 2024
• (Video) How Python Harnesses Rust through PyO3 - May 18, 2024
• (Video) Combining Rust and Python: The Best of Both Worlds? - Mar 1, 2024
• (Video) Extending Python with Rust using PyO3 - Dec 16, 2023
• A Week of PyO3 + rust-numpy (How to Speed Up Your Data Pipeline X Times) - Jun 6, 2023
• (Podcast) PyO3 with David Hewitt - May 19, 2023
• Making Python 100x faster with less than 100 lines of Rust - Mar 28, 2023
• How Pydantic V2 leverages Rust's Superpowers - Feb 4, 2023
• How we extended the River stats module with Rust using PyO3 - Dec 23, 2022
• Nine Rules for Writing Python Extensions in Rust - Dec 31, 2021
• Calling Rust from Python using PyO3 - Nov 18, 2021
• davidhewitt's 2021 talk at Rust Manchester meetup - Aug 19, 2021
• Incrementally porting a small Python project to Rust - Apr 29, 2021
• Vortexa - Integrating Rust into Python - Apr 12, 2021
• Writing and publishing a Python module in Rust - Aug 2, 2020

Contributing

Everyone is welcomed to contribute to PyO3! There are many ways to support the project, such as:

• help PyO3 users with issues on GitHub and Discord
• improve documentation
• write features and bugfixes
• publish blogs and examples of how to use PyO3

Our contributing notes and architecture guide have more resources if you wish to volunteer time for PyO3 and are searching where to start.

If you don't have time to contribute yourself but still wish to support the project's future success, some of our maintainers have GitHub sponsorship pages:

• davidhewitt
• messense

License

PyO3 is licensed under the Apache-2.0 license or the MIT license, at your option.

Python is licensed under the Python License.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in PyO3 by you, as defined in the Apache License, shall be dual-licensed as above, without any additional terms or conditions.