Regex Tester

Development Client-side regex regular expression pattern matcher test

This tool runs entirely client-side, in your browser: your data is never sent anywhere.

What it does

Lets you write a JavaScript regular expression, apply it to a test string, and immediately see every match highlighted in the text, plus a detailed breakdown of each match (index, full match, capture groups, named groups).

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How it works

Your pattern and flags are passed straight to JavaScript's native RegExp engine (new RegExp(pattern, flags)).
With the global flag g, every non-overlapping match is found via repeated calls to RegExp.exec(); without it, only the first match is reported.
Matches are highlighted directly inside the test string, and each match lists its index, full matched text, numbered capture groups ($1, $2...), and named groups ((?<name>...)) if any are used.
Invalid patterns show the exact error message thrown by the engine instead of silently failing.

Everything runs locally in your browser — nothing is sent anywhere.