Free online regular expression tester with real-time highlighting and match details
Privacy-first
All testing happens locally
Real-time
Instant match highlighting
Match details
Groups, indices & counts
A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for pattern matching within strings, such as finding, replacing, or validating text. Regex is supported in virtually every programming language and text editor.
g (global) finds all matches instead of just the first. i (case-insensitive) ignores letter casing. m (multiline) makes ^ and $ match start/end of each line. s (dotAll) makes . match newline characters. u (unicode) enables full Unicode matching.
Replace mode lets you specify a replacement string that will substitute each match. You can use special patterns like $1, $2 to reference captured groups, $& for the entire match, $` for text before the match, and $' for text after the match.
Yes, all regex testing is performed entirely in your browser using the native JavaScript RegExp engine. Your patterns and test strings never leave your device. No data is transmitted to any server.
This tool uses the native JavaScript RegExp engine, which supports standard regex syntax including character classes, quantifiers, anchors, lookaheads, lookbehinds, named groups, and Unicode properties. The syntax is the same as what you would use in JavaScript code.
A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for pattern matching within strings, such as finding, replacing, or validating text. Regex is supported in virtually every programming language and text editor.
g (global) finds all matches instead of just the first. i (case-insensitive) ignores letter casing. m (multiline) makes ^ and $ match start/end of each line. s (dotAll) makes . match newline characters. u (unicode) enables full Unicode matching.
Replace mode lets you specify a replacement string that will substitute each match. You can use special patterns like $1, $2 to reference captured groups, $& for the entire match, $` for text before the match, and $' for text after the match.
Yes, all regex testing is performed entirely in your browser using the native JavaScript RegExp engine. Your patterns and test strings never leave your device. No data is transmitted to any server.
This tool uses the native JavaScript RegExp engine, which supports standard regex syntax including character classes, quantifiers, anchors, lookaheads, lookbehinds, named groups, and Unicode properties. The syntax is the same as what you would use in JavaScript code.