What regex syntax is supported?

This tool uses JavaScript's native RegExp engine, supporting all standard syntax including character classes, quantifiers, groups, lookahead/lookbehind, and named groups.

What do the flags mean?

g (global): find all matches. i (case-insensitive): ignore case. m (multiline): ^ and $ match line boundaries. s (dotAll): . matches newlines. u (unicode): full Unicode support.

Why aren't all matches highlighted?

Make sure the 'g' (global) flag is enabled to find all matches. Without it, only the first match is found.

Can I use named groups?

Yes! Use (? ...) syntax for named groups. The tool will display group names and values in the match details.

Regex Tester

Your files never leave your device

Test and debug your regular expressions with real-time matching and highlighting. Supports JavaScript regex syntax. All processing happens in your browser.