★ Free Developer Tool
Regex Tester
Test JavaScript regular expressions live, with highlighted matches and groups.
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Runs entirely in your browser. Your files and text are never uploaded to our server.
About this toolRegex Tester highlights every match as you type a pattern, and lists capture groups, so you can build and debug regular expressions quickly.
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Regex Tester highlights every match as you type a pattern, and lists capture groups, so you can build and debug regular expressions quickly.
More about Regex TesterHow to use, good to know & FAQ
How to use Regex Tester
- Type a pattern and choose flags (g, i, m, s).
- Paste test text; matches are highlighted instantly.
- Review the list of matches and groups.
Frequently asked questions
Which regex flavour is used?
JavaScript (ECMAScript), the same engine your browser uses.
Can I see capture groups?
Yes. Groups are shown for each match.
When to use Regex Tester
- Build validation patterns for forms
- Debug search-and-replace expressions
- Extract data from logs
- Learn regex with instant feedback
📘 Read the guide: JSON Formatting & Validation: A Beginner’s Guide With Examples