Regex Tester
Test JavaScript regular expressions.
Regex
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How it works
How it works
Patterns are compiled with JavaScript's RegExp engine. Using String.matchAll lists all non‑overlapping matches.
- Flags: g (global), i (case‑insensitive), m (multiline), s (dotAll), u (Unicode), y (sticky).
- Some features (lookbehind) require modern engines; older browsers may not support them.
- Beware of catastrophic backtracking in poorly designed patterns.
Privacy & Security
Everything runs locally.
Accuracy, Limits & Tips
Lookbehind support depends on your browser.
Examples
- Find all email-like substrings in text.
Looking for broader guides and best practices? Visit the ToolsAreUs Blog for indexes (like the full tool list) and articles (e.g. secure password generation).