JavaScript regex (ECMAScript 2018+), which includes named capture groups, lookbehind assertions, and Unicode property escapes. The tester runs in the browser, so the behavior exactly matches what you'd get in a JS app.
Does it highlight all matches in real time?
Yes. Matches are highlighted in the test string as you type the pattern, with separate colors for groups.
Can I test global, case-insensitive, and multiline flags?
Yes. Toggle g, i, m, s (dotAll), u (Unicode), and y (sticky) flags with dedicated buttons.
Does it show capture groups?
Yes. Named and numbered capture groups are listed below the match highlights with their matched values.