Ruff vs SonarQube

Free and open source

From $34 per month (SonarQube Cloud Team, up to 100k lines of code)

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

SonarQube Cloud Team starts at $34/month for 100k lines of code and scales in LOC increments. Self-managed SonarQube Server (Developer, Enterprise, Data Center) is licensed per instance per year by lines of code, and SonarSource no longer publishes those figures — you have to ask sales. Branch and PR analysis requires a paid edition either way.

Everything, self-hosted

Community Build is free and self-hosted; SonarQube Cloud is free for public projects and for private projects up to 50k lines of code.

Category standard

Astral · since 2022

Category standard

Sonar · since 2007

• 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.

• Clean-as-you-code is the only quality-gate model that reliably works on legacy codebases.
• Very broad language coverage from one tool and one gate.
• Self-hosting satisfies organisations that cannot send source code externally.

• 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.

• Branch and pull-request analysis — the feature most teams actually need — is paid only.
• Default rule sets are noisy until tuned to the team.
• Self-hosted instances need real resources and maintenance.

Every Python project.

Polyglot organisations that need one quality gate across every repository.