Optimise regex

Find conservative simplifications for a regular expression without changing its captures.

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ToolRegex Optimizer
Input
Output
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How it works

The pattern is inspected for redundant groups, repeated alternation, unnecessary escapes, and class simplifications; safe rewrites are proposed while semantic constructs remain untouched. Suggestions are not a proof of equivalent runtime performance.

  • Conservative rewrites protect observable capture indexes.
  • Backtracking behavior can remain even after cosmetic cleanup.

Worked example

Simplify character classes and quantifiers
Optimize a regex by replacing verbose character classes with shortcuts
Input
											[0-9]+[a-zA-Z0-9_]{0,1}
Output
												\d+\w?

When to use this

Validation review, hot log filters, and regex maintenance inspect optimization ideas.

Edge cases

  • Removing a capture changes numbered group indexes.
  • Lookarounds can make similar-looking patterns non-equivalent.
  • Nested quantifiers can still cause catastrophic backtracking.

References