Ruff

Ruff replaced Flake8, Black, isort, pyupgrade, and autoflake — all of them — with a single tool that runs 100-200x faster. Written in Rust by Astral (now part of OpenAI's Codex team), it lints and formats your Python in the time it takes Black to parse its config file. 900+ rules, near-identical Black formatting output, and it just works.

There's no real competition anymore. Black is slower. Flake8 needs plugins for what Ruff does natively. pylint is comprehensive but glacial. Ruff is the default Python linter/formatter in 2026 — Django, Zulip, and most major projects have switched.

Use Ruff for every Python project. No exceptions. Add it to your pre-commit hooks and CI pipeline today.

The catch: it's not a type checker (use mypy or Astral's new ty for that). The pace of development means occasionally a rule behaves differently between versions — pin your Ruff version in CI. And the OpenAI acquisition raises questions about long-term open-source commitment, though the tools remain MIT-licensed for now.