Test regular expressions with live matching, highlights, and capture groups.
This tool uses JavaScript's built-in RegExp engine, which supports the ECMAScript specification including features like lookahead, lookbehind, named capture groups, and the dotAll (s) flag.
No. All matching runs entirely in your browser. Your patterns and test strings never leave your device.
Different programming languages implement slightly different regex flavours. Features like lookbehind length restrictions, possessive quantifiers, or atomic groups vary across engines. Always test in your target language as well.