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flowtools/Regex Tester

Regex Tester

Test and debug regular expressions with live matching.

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Enter a pattern to start

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How it works

  1. 1

    Type your regular expression pattern and set any flags (g, i, m, etc.).

  2. 2

    Paste or type test text — matches highlight instantly as you type.

  3. 3

    Review each match with its index and named capture groups.

Why choose FlowTools

  • Live highlighting shows matches directly in your text with no delay.
  • Full support for named capture groups and all standard regex flags.
  • Detailed match list with index positions for debugging complex patterns.
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Frequently Asked Questions

All standard flags: g (global), i (case-insensitive), m (multiline), s (dotall), u (unicode), and y (sticky).
Yes. The tester uses your browser's native RegExp engine, which supports lookaheads, lookbehinds, and all modern regex features.
No. All matching happens locally in your browser. Your text and patterns never leave your device.