---
id: mccabe
version: "0.7.0"
license: Expat license
license_treatment: permissive
maintenance: active
---

# mccabe — McCabe checker, plugin for flake8

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install mccabe
uv add mccabe
poetry add mccabe

## Description

McCabe complexity checker
=========================

Ned's script to check McCabe complexity.

This module provides a plugin for ``flake8``, the Python code checker.


Installation
------------

You can install, upgrade, or uninstall ``mccabe`` with these commands::

  $ pip install mccabe
  $ pip install --upgrade mccabe
  $ pip uninstall mccabe


Standalone script
-----------------

The complexity checker can be used directly::

  $ python -m mccabe --min 5 mccabe.py
  ("185:1: 'PathGraphingAstVisitor.visitIf'", 5)
  ("71:1: 'PathGraph.to_dot'", 5)
  ("245:1: 'McCabeChecker.run'", 5)
  ("283:1: 'main'", 7)
  ("203:1: 'PathGraphingAstVisitor.visitTryExcept'", 5)
  ("257:1: 'get_code_complexity'", 5)


Plugin for Flake8
-----------------

When both ``flake8 2+`` and ``mccabe`` are installed, the plugin is
available in ``flake8``::

  $ flake8 --version
  2.0 (pep8: 1.4.2, pyflakes: 0.6.1, mccabe: 0.2)

By default the plugin is disabled.  Use the ``--max-complexity`` switch to
enable it.  It will emit a warning if the McCabe complexity of a function is
higher than the provided value::

    $ flake8 --max-complexity 10 coolproject
    ...
    coolproject/mod.py:1204:1: C901...

## AI interpretation — verify before relying

Measures cyclomatic complexity of Python functions to identify overly complex code; works as a standalone checker or integrates with flake8 to flag functions exceeding a complexity threshold.

Verdict: A mature, actively maintained tool for detecting overly complex functions in Python code. Zero known vulnerabilities, permissive licensing, and zero runtime dependencies make it a low-friction addition to code-quality workflows. Best used as a flake8 plugin or standalone checker to enforce complexity thresholds across a codebase.

[View on SkillFed](https://skillfed.io/packages/mccabe) · [View on PyPI](https://pypi.org/project/mccabe/)