Ruff Python Linter

Ruff is an extremely fast Python linter and code formatter written in Rust by Charlie Marsh, designed as a drop-in replacement for Flake8, isort, and Black. The tool is 10 to 100 times faster than existing Python linters, capable of linting an entire codebase in milliseconds rather than minutes. With over 48,000 stars on GitHub and developed under Astral (the company also behind the uv package manager and the ty type checker), Ruff supports over 900 built-in rules derived from popular Flake8 plugins including pycodestyle, pyflakes, flake8-bugbear, flake8-comprehensions, flake8-simplify, pydocstyle, pylint, and isort. The latest version 0.15.20 adds Python 3.14 compatibility, new linting rules, and incremental improvements. Ruff automatically fixes many issues it detects, supports pyproject.toml configuration, and integrates with all major editors through VS Code, IntelliJ, Vim, Neovim, and Emacs extensions. The tool includes a formatter that produces output compatible with Black while running at Rust speed. An online playground at play.ruff.rs allows trying Ruff without installation. Ruff is used by major open source projects including FastAPI, Pandas, and LangChain, and has become the most popular Python linter by adoption in 2025-2026.