Code Analysis in Python

Ruff is a linter and formatter written in Rust that reimplements rules from Flake8 and many of its plugins, isort, pyupgrade and others, and its formatter is designed to match Black's output. Many projects have replaced Flake8, isort and Black with Ruff alone. Pylint performs deeper analysis with more type inference and catches different problems, at the cost of speed and configuration. Bandit looks specifically for common security issues. pre-commit runs any of these tools automatically before each commit.

For type checking, mypy is the original reference checker. Pyright, from Microsoft, is fast and powers type checking in VS Code's Pylance extension. ty, from Astral (the makers of Ruff and uv), and Pyrefly, from Meta, are newer Rust-based checkers and language servers focused on speed. Rules and inference differ between checkers, so pick one per project and run it in CI.

Other listed tools cover narrower jobs: vulture finds dead code, import-linter enforces architectural layers between packages, complexipy measures cognitive complexity, ast-grep searches and rewrites code by syntax tree, and Rope is a refactoring library used by editors. These are most useful as targeted checks added to CI once the basics are in place: a team that already runs Ruff and a type checker can add import-linter to keep layers separate or vulture to find code that nothing calls anymore, without slowing down the everyday edit and commit loop.