Free Online Regex Tester
RunDev
Test regular expressions with live highlighting and match detailsUpdated 2026-03-16
/
/
g
⚡ Uses JavaScript's native RegExp engine. Supports lookahead, lookbehind, named groups, and Unicode properties.
How to Use Regex Tester
- Copy the formatted result
- Select formatting options
- Click Process or press Ctrl+Enter
- Check validation messages for issues
All processing happens locally in your browser. Your data is never uploaded to any server.
Frequently Asked Questions
Is Regex Tester free to use?
Yes, completely free. No signup, no limits. All pattern matching happens in your browser.
What regex engine is used?
JavaScript's native RegExp engine (ECMAScript). It supports lookahead, lookbehind, named capture groups, and Unicode properties.
Does it work on mobile?
Yes, it works on all devices including phones and tablets. The interface is fully responsive.
Is my data safe?
Absolutely. Everything runs locally in your browser using JavaScript. No data is uploaded to any server.
Cite this tool:
"Regex Tester." RunDev, run-dev.com, https://run-dev.com/tools/regex-tester/. Accessed 2026-03-16.