Regex Tester (JavaScript)

Build and test your JavaScript regular expressions in real-time. See matches highlighted instantly as you type.

/ /

Test String

Match Results

No matches found.

How the Regex Tester Works

This tool provides a simple and interactive way to test your JavaScript regular expressions. The results update live as you modify your pattern or test string.

✔️ Enter your regular expression pattern between the slashes (`/ /`).
✔️ Add any flags (like `g` for global, `i` for case-insensitive) in the flags input box.
✔️ Type or paste the text you want to test in the "Test String" area.
✔️ Matches will be highlighted instantly in the results box below.
✔️ A detailed list of all matches and their positions will be displayed.

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FAQs about the Regex Tester

What flavor of Regex does this use?

This tool uses the JavaScript regular expression engine, which is the same one that runs in your web browser.

Is my data secure?

Yes. All testing is performed in your browser. No data is ever sent to a server, ensuring your privacy.

What do the flags `g`, `i`, and `m` mean?

g (global): Finds all matches instead of stopping after the first one. i (case-insensitive): Ignores case when matching. m (multiline): Allows start (^) and end ($) anchors to match the start/end of lines, not just the whole string.

Why is my pattern red?

If the input box for your pattern turns red, it means your regular expression has a syntax error and is invalid. An error message will appear below the input to help you fix it.