pypfmt

An opinionated formatter and sorter for pyproject.toml files. Produces deterministic, consistently-ordered output so you can diff configuration across many Python projects and copy settings between them without noise.

Features

• Sort tables and keys with opinionated defaults — [project], [build-system], and [dependency-groups] always come first; common tool sections follow a predictable order
• Format whitespace and style via taplo for consistent indentation, trailing commas, and column alignment
• Preserve all data — no keys, values, or comments are lost or reordered when order matters (e.g. pytest.ini_options.addopts)
• Idempotent — running the tool twice produces identical output
• Pre-commit hook — drop-in integration with pre-commit
• Configurable — override defaults per-project via [tool.pypfmt]

Installation

pip install pypfmt

Or using uv (recommended):

uv add pypfmt

Usage

Format files in-place

pypfmt pyproject.toml

Multiple files (useful for monorepos):

pypfmt services/*/pyproject.toml

Check mode (CI)

Exit non-zero if any file needs formatting, without modifying files:

pypfmt --check pyproject.toml

Diff mode

Print a unified diff of proposed changes without modifying files:

pypfmt --diff pyproject.toml

Combined check + diff

Print the diff and exit non-zero if changes are needed:

pypfmt --check --diff pyproject.toml

Stdin / stdout

Pipe input through pypfmt and receive formatted output on stdout:

cat pyproject.toml | pypfmt

Pre-commit hook

Add to your .pre-commit-config.yaml:

repos:
  - repo: https://github.com/bitflight-devops/pyproject-fmt
    rev: v1.0.0  # replace with the latest tag
    hooks:
      - id: pypfmt

language: python is used so pre-commit installs taplo and all other dependencies automatically.

Configuration

Add a [tool.pypfmt] section to your pyproject.toml to override defaults.

Sort order

[tool.pypfmt]
# Replace the root-level table ordering entirely
sort-first = ["project", "build-system", "dependency-groups"]

# Or append extra tables to the default ordering
extend-sort-first = ["my-custom-tool"]

# Disable alphabetical key sorting within tables
sort-table-keys = false

Per-table overrides

[tool.pypfmt]
# Extend the built-in per-table overrides
[tool.pypfmt.extend-overrides]
"tool.mypy" = { first = ["strict", "plugins"] }
"project.optional-dependencies.*" = { inline_arrays = true }

taplo formatting options

[tool.pypfmt]
# Replace all taplo options
taplo-options = ["column_width=100", "indent_string=  "]

# Or append extra options to the defaults
extend-taplo-options = ["column_width=100"]

Comment handling

[tool.pypfmt]
comments-header = true   # preserve file-level header comments (default: true)
comments-footer = true   # preserve file-level footer comments (default: true)
comments-inline = true   # preserve inline comments (default: true)
comments-block  = true   # preserve block comments (default: true)

Default opinionated behaviour

Development

Prerequisites

• Python 3.11+
• uv for package management

Setup

git clone https://github.com/bitflight-devops/pyproject-fmt.git
cd pyproject-fmt
uv sync --all-groups

Running Tests

uv run poe test

# With coverage
uv run poe test-cov

# Across all Python versions
uv run poe test-matrix

Code Quality

# Run all checks (lint, format, type-check)
uv run poe verify

# Auto-fix lint and format issues
uv run poe fix

Pre-commit hooks (prek)

prek install
prek run --all-files

Documentation

uv run poe docs-serve

License

This project is licensed under the MIT License - see the LICENSE file for details.