Regex Tester

Test and debug regular expressions with real-time matching and group highlighting. A free browser-based regex tester with instant feedback for developers.

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How to use

  1. Enter your regular expression pattern in the pattern input field.
  2. Set regex flags such as global, case-insensitive, or multiline as needed.
  3. Type or paste test strings in the text area below to see matches highlighted.
  4. Review matched groups and capture results in the details panel on the right.

FAQ

Which regex flavor does this tester use?

It uses JavaScript's built-in RegExp engine, which follows the ECMAScript specification. All pattern matching executes in your browser, so your test data stays completely private.

Can I see capture groups and named groups?

Yes. The tool highlights each capture group with a distinct color and lists all matched groups including named groups. Everything runs locally in the browser with no server calls.

Is there a limit on the length of test input?

There is no hard limit since matching runs in your browser. Very long inputs may take slightly more time depending on pattern complexity, but your data never leaves the browser.