py2fern

Generate Fern API documentation from Python packages using static analysis.

Simplified fork of sphinx-autodoc2 focused purely on Python → Fern markdown output.

Installation

pipx install py2fern

Upgrading

To upgrade to the latest version:

pipx upgrade py2fern

Or if installed with pip:

pip install --upgrade py2fern

Check your current version:

py2fern --version

Usage

Generate Fern markdown documentation:

py2fern write /path/to/your/package

Specify output directory:

py2fern write /path/to/your/package --output ./docs/api

Debug Mode

Show warnings for functions missing return type annotations:

py2fern write /path/to/your/package --output ./docs/api --debug

Warnings appear in yellow and help identify functions that should have type annotations added.

Legacy Parser Mode

Use the old regex-based parser instead of the default docstring_parser:

USE_REGEX_PARSER=1 py2fern write /path/to/your/package --output ./docs/api

Output

This creates:

• MDX files with Fern-compatible frontmatter and slugs
• navigation.yml for Fern docs structure
• Consistent ParamFields for all Parameters and Returns sections

Acknowledgments

This project is a fork of the excellent sphinx-autodoc2 by Chris Sewell. All credit for the core functionality goes to the original project.

Development

All configuration is mainly in pyproject.toml.

Use tox to run the tests.

pipx install tox
tox -av

Use pre-commit to run the linters and formatters.

pipx install pre-commit
pre-commit run --all-files
# pre-commit install

flit is used to build the package.

pipx install flit
flit build