Regex Tester
Test regular expressions against sample text in real time. See matches, groups, and capture results instantly.
Frequently Asked Questions
What are regex flags?
Flags modify how the pattern matches: g (global), i (case-insensitive), m (multiline), s (dotAll), u (unicode).
What are capture groups?
Capture groups, defined by parentheses, extract specific parts of a match. For example, (\d+)-(\d+) captures two number groups.
Why does my regex hang?
This can happen with catastrophic backtracking. Avoid nested quantifiers like (a+)+ and use atomic groups or possessive quantifiers.