Regex Tester

Test and debug regular expressions with real-time match highlighting.

About Regular Expressions

Regular expressions (regex) are powerful patterns used for searching, matching, and manipulating text. They are essential in programming, data validation, log parsing, and text processing. This tool lets you test JavaScript-flavored regular expressions in real-time with instant visual feedback — highlighting matches directly in your test string. All processing runs entirely in your browser using the native RegExp engine.

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Frequently Asked Questions

How does the Regex Tester work?▾
The tool creates a JavaScript RegExp object from your pattern and flags, then uses matchAll() to find all matches in your test string. Everything runs in your browser — no data is sent to any server.
What regex flags are available?▾
You can toggle five flags: g (global — find all matches), i (case-insensitive), m (multiline — ^ and $ match line boundaries), s (dotAll — . matches newlines), and u (unicode — treat pattern as Unicode).
Can I use capture groups and named groups?▾
Yes. Both numbered capture groups like (abc) and named groups like (?<name>abc) are fully supported. Group values are displayed in the match details table for each match.