Regex Tester
Type a JavaScript regular expression and some test text. Matches are highlighted live, and every capture group is listed below.
Matches: 0
About this regex tester
This tool uses your browser's built-in JavaScript RegExp engine, so results match what you will get in Node.js, React and any front-end code. Nothing is sent to a server.
Regex flags explained
g finds all matches instead of only the first, i ignores letter case, m makes ^ and $ match at line boundaries, s lets . match newlines, and u enables full Unicode matching.
Tip
Very complex patterns with nested repetition can cause catastrophic backtracking and freeze the page. If that happens, simplify the pattern.
Frequently asked questions
Which regex flavor does this tester use?
JavaScript (ECMAScript) regular expressions. Most syntax is shared with other languages, but features like lookbehind, named groups and Unicode escapes vary by engine.
How do I match an email address with regex?
A practical pattern is [\w.+-]+@[\w-]+\.[\w.-]+. Perfect email validation with regex is very hard, so also validate by sending a confirmation email.
Why does my regex only find one match?
Enable the g (global) flag to find every match in the text.
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