Which regex flavor is supported?
It targets JavaScript-style regular expressions so results align with browser and Node environments, including common flags and capture-group behavior.
Regex Tester
Test JavaScript regular expressions with live match highlighting, capture groups, and replace previews. Includes a cheatsheet and a mobile-friendly layout for quick pattern debugging.
Useful for: regex tester, javascript regexp, match, replace, capture groups, pattern debugging.
Common questions
Can I preview replacements?
Yes. You can iterate on replace workflows and see match boundaries and capture groups with visual feedback before copying a finished pattern into code.
Does it work on mobile?
The layout is tuned for smaller screens and includes helpful reference material while you test patterns away from a desktop IDE.
Is this a free online regex tester?
Yes. It is a free browser regex playground for writing, testing, and explaining JavaScript regular expressions without installing an editor plugin.
Can I debug capture groups visually?
Yes. Live highlighting and group extraction make it easier to see what each parenthesis captured, which is often the hardest part of regex debugging.
Should I use this for production validation?
Use it to design and verify patterns quickly, then keep the same JavaScript RegExp semantics in your application tests. Extremely large inputs can still be expensive depending on the pattern.