---
id: extension-helpers
version: "1.4.0"
license: BSD 3-Clause License
license_treatment: permissive
maintenance: active
---

# extension-helpers — Utilities for building and installing packages with compiled extensions

License: permissive · Maintenance: active · Downloads: 1.7M/mo

## What it is and what it does

extension-helpers is a setuptools plugin that streamlines the build configuration for Python packages containing compiled C or Cython extensions. Developed by the Astropy project, it abstracts away common boilerplate and configuration patterns that would otherwise require manual setup.py or pyproject.toml tuning. The package depends on setuptools and tomli for parsing configuration files.

It is intended as a general-purpose tool for any Python package author building extensions, not just Astropy-specific projects. The package is actively maintained, in production-stable status, and carries no known security vulnerabilities. Installation is straightforward with low dependency friction.

Use it for:

- Simplify build configuration when packaging a Python library that wraps C code or uses Cython modules
- Reduce boilerplate in setup.py or pyproject.toml for projects with multiple compiled extensions
- Ensure consistent extension build behavior across different development and CI environments
- Integrate extension building into a setuptools-based workflow without manual compiler flag management

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides build helpers and utilities for Python packages that include compiled C or Cython extensions, integrating with setuptools to simplify the extension build process.

Yes, if you are building a Python package with C or Cython extensions and want to reduce build configuration complexity. The low install friction, active maintenance, permissive license, and lack of known vulnerabilities make it a safe dependency. Skip it if your project uses a different build system or has no compiled extensions.

## Install

pip install extension-helpers
uv add extension-helpers
poetry add extension-helpers

## Installing extension-helpers

Before you install: Low friction installation with only setuptools and tomli as runtime dependencies. Active maintenance with recent commits and stable production status.

License in practice: BSD 3-Clause License is permissive; you may use, modify, and distribute this package freely in commercial and private projects with minimal restrictions.

Quickstart:

pip install extension-helpers

In setup.py or pyproject.toml, use extension-helpers as a build backend or build requirement alongside setuptools to configure C/Cython extension compilation.

Requires Python 3.10 or later; a C compiler and development headers are typically needed to build extensions at install time.

Verify before relying:

- Whether this package is necessary for your build or if setuptools alone suffices for your extension use case
- Specific Cython or C compilation toolchain requirements beyond what the fact sheet documents

## Package facts

- License: BSD 3-Clause License (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 1.7M/month (top 5,000 on PyPI)
- Known vulnerabilities: none known

## Tags

build C extensions python, cython extension helpers, setuptools extension build, compiled extension packaging, python c extension tools, build-system, cython, setuptools-plugin

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