About Regex Tester
Test JavaScript regular expressions online with live match feedback. This regex tester uses the same ECMAScript engine as your browser and Node, so patterns behave like production JS. Keep sensitive sample strings local while you tune flags and capture groups — no pattern upload required.
What stays local: Patterns and sample strings you test.
What you can do with Regex Tester
- JavaScript / ECMAScript regex flavor
- Live match highlighting
- Flags and capture group inspection
- Private — patterns never uploaded
How to use Regex Tester
- Enter a pattern. Type your regular expression and select flags (g, i, m, etc.).
- Add test text. Paste sample input you want to match against.
- Review matches. Inspect highlights and capture groups, then refine the pattern.
Privacy
What stays local: Patterns and sample strings you test. DevTooKit is local-first — no signup wall, no server-side processing for this tool, and no watermark on results.
Related tools
FAQ — Regex Tester
Privacy, offline use, and how this free online tool works.
Which regex flavor does this tester use?
JavaScript (ECMAScript) regex via the browser engine — the same flavor as String.match / RegExp in Node and the browser.
Does my regex leave this device?
No. Patterns and test strings stay in this browser tab.
Is the regex tester free?
Yes — free online regex testing with no account.