What is a build frontend?

A build frontend is a tool that invokes build backends to create Python packages. It provides the user interface and orchestrates the build process while delegating the build work to build backends.

Common Build Frontends

• pip: Default package installer, builds during installation
• build: Dedicated PEP 517 builder from PyPA
• uv: High-performance alternative to pip
• poetry/hatch/pdm: Full-featured project management tools with build capabilities

Key Responsibilities

• Discovering and loading build backends
• Managing build environments
• Handling build configuration
• Processing build output (wheels/sdists)
• Reporting build progress and errors

Example Usage

Using the build frontend to create distributions:

python -m build .             # Build both wheel and sdist
python -m build --wheel .     # Build only wheel
python -m build --sdist .     # Build only sdist

Using uv as a build frontend:

uv build                      # Build both formats
uv build --sdist             # Build only sdist
uv build --wheel             # Build only wheel

The separation between frontends and backends allows tools to focus on their strengths while maintaining compatibility through standardized interfaces.