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Regex Tester

Test regular expressions against text. See all matches highlighted with capture groups.

Regular expressions are powerful but notoriously tricky to get right. This regex tester lets you type a pattern, set flags, and test it against any text to see all matches instantly. Each match is listed with its position and any capture groups.

The tool uses JavaScript's native RegExp engine, so it supports all standard regex features: character classes, quantifiers, lookaheads, lookbehinds, named groups, and more. Everything runs in your browser with no data sent to any server.

Tester

Results

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How to Use

  1. Enter your regex pattern
  2. Set optional flags (g for global, i for case-insensitive, m for multiline)
  3. Paste your test string
  4. Click Calculate to find matches

FAQ

Which regex flavor is used?

The tool uses JavaScript's native RegExp engine. It supports all standard features including lookahead, lookbehind, named groups, and Unicode.

What flags are supported?

Common flags: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode). Combine them like 'gi'.

Is my text sent to a server?

No. All testing runs in your browser. Your data never leaves your device.

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