Ruff vs ESLint

Free and open source

Free and open source

Free and open source. You pay in engineering time and CI minutes.

Free and open source. You pay in engineering time and CI minutes.

Everything, self-hosted

Everything, self-hosted

Category standard

Astral · since 2022

Category standard

OpenJS Foundation · since 2013

• Replaces Flake8, isort, Black, pyupgrade and more with a single fast binary.
• Fast enough to run on every keystroke in the editor.
• Straightforward migration from existing Flake8 configurations.

• The plugin ecosystem lets you enforce almost any convention as a rule.
• Autofix handles a large share of findings without human effort.
• Universal — every JavaScript tool integrates with it.

• Not every niche Flake8 plugin rule has been ported.
• Type checking is a separate concern — you still need mypy or ty.
• Rapid release cadence occasionally changes behaviour.

• Configuration is a real project of its own, and the flat-config migration caused significant churn.
• Slow on large codebases without caching.
• Rule sprawl produces bikeshedding unless someone owns the config.

Every Python project.

Every JavaScript and TypeScript project.