Regex Tester

Your pattern runs as a JavaScript RegExp in the browser; matches are highlighted and capture groups listed for each match. Without the g flag only the first match is found. The default example (\d{3})-(\d{4})-(\d{4}) captures a Korean phone number and its parts.

Toggle g (global), i (ignore case), m (multiline: ^ $ per line), s (dot matches newlines) and u (unicode). Named groups (?<name>…) and lookarounds (?=…) (?<=…) work as your browser supports them.

The regex runs in a separate Web Worker and stops after 1 second, so patterns like (a+)+$ that blow up through backtracking cannot freeze the page. Syntax may differ slightly from Python or Java regex.