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Regex Tester

Type a pattern, paste sample text, see every match highlighted live.

No pattern yet

Writing a regular expression that actually matches what you intend is easier with live feedback — test your pattern against real sample text and see matches highlighted instantly as you type.

How it works

  1. Type a patternEnter your regular expression and any flags you need.
  2. Paste sample textMatches highlight live as you type in either field.
  3. Check the match countSee exactly how many matches your pattern finds, and where.

Good to know

  • Uses JavaScript's native RegExp engine, the same one your browser's own code runs
  • Handles zero-length matches safely, so a pattern like an empty lookahead won't freeze the page
  • Caps at 5,000 highlighted matches on very large inputs, to keep the page responsive
  • Matched text is escaped before display, so pasting HTML or script-like content is safe to test

FAQ

Is my text sent anywhere?

No — matching runs entirely in your browser using JavaScript's native regex engine.

What flags are supported?

Standard JS regex flags: g (global), i (case-insensitive), m (multiline), s (dotall), u (unicode).

Will this match exactly the same as Python or Java regex?

Mostly, but not always — this uses JavaScript's regex engine specifically. Minor differences exist in lookbehind support, named groups, and some escape sequences compared to Python's re or Java's regex.

Does this work on Mac, Windows, or my phone?

Yes — it runs in any modern browser on Mac, Windows, Chromebook, iPhone, or Android. No app or software to install.