Many of the 968 rules that were not previously enabled by default catch severe issues including syntax errors and immediate runtime errors, and will now be brought to developers' attention without any Ruff configuration.

The expanded default rule set surfaces severe bugs like syntax errors and runtime crashes that previously required explicit configuration to detect. ✦ AI generated

Brent Westbrook · Simon Willison's Weblog · 2026-07-25 · original ↗

Since Ruff's default rule set was last modified in v0.1.0, the number of rules in Ruff has grown from 708 to 968. Many of these rules catch severe issues, including syntax errors and immediate runtime errors but were not previously enabled by default. With the new rule set, Ruff will bring these issues and many others to your attention without any Ruff configuration.

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